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conference "IDM2008 - Identification of Dark Matter 2008"
chaired by Lars Bergström (Stockholm University) , Jan Conrad (Stockholm University) , Joakim Edsjö (Stockholm University) , Stephan Hofmann (Nordita) , Per-Olof Hulth (Stockholm University) , Edvard Mörtsell (Stockholm University) , Tommy Ohlsson (KTH) , Mark Pearce (KTH)
  from Monday 18 August 2008 (08:00)
to Friday 22 August 2008 (20:00)
at AlbaNova ( Oskar Klein auditorium )


Thanks everyone for coming to idm2008 and making it a good conference.

Presentation slides are available online (click Timetable on the left, then set the detail level to Contributions and Apply to see all talks). A direct link to the schedule is here.

Proceedings are published by PoS. The deadline for submission of proceedings has been extended to November 17, 2008. All authors should have received an invitation to submit with instructions on how to submit them to the PoS web page. If you have not, let us know.


Welcome to the conference site for idm2008 - identification of dark matter 2008, to be held at AlbaNova University Centre, Stockholm, Sweden, August 18-22, 2008. The main topics of the conference are

  • Dark matter candidates
  • Dark matter direct searches
  • Dark matter indirect searches
  • Connections with accelerator searches
  • Halo models and structure formation
  • Weak lensing
  • Neutrino physics
  • Cosmology and dark energy
The conference will include both invited and contributed talks as well as a few more specialized sessions and a poster session.

Local Organizing Committee

L. Bergström (Stockholm University), J. Conrad (Stockholm University), J. Edsjö (Stockholm University), S. Hofmann (Nordita, Stockholm), P-O. Hulth (Stockholm University), E. Mörtsell (Stockholm University), T. Ohlsson (Royal Institute of Technology, Stockholm) and M. Pearce (Royal Institute of Technology, Stockholm).

International Advisory Committee

Dan Akerib (CWRU), Elena Aprile (Columbia), Rita Bernabei (Rome), Gianfranco Bertone (IAP, Paris), Karl van Bibber (LLNL), Elliott Bloom (SLAC), David Cline (UCLA), Katie Freese (Michigan), Rick Gaitskell (Brown), Anne Green (Nottingham), Henk Hoekstra (UVic), Dan Hooper (FNAL), Marc Kamionkowski (Caltech), Stavros Katsanevas (IN2P3), Lawrence Krauss (CWRU), Vitaly Kudryavtsev (Sheffield) Manfred Lindner (MPI Kernphysik, Heidelberg), Bela Majorovits (MP), Ben Moore (Zürich), Aldo Morselli (Rome), Robert C. Nichol (Portstmouth), Georg Raffelt (MP Physik, Munich), Leszek Roszkowski (Sheffield), Bernard Sadoulet (Berkeley), Pierre Salati (Annecy), Neil Spooner (Sheffield), Max Tegmark (MIT), Dan Tovey (Sheffield), Piero Ullio (SISSA) and Simon White (MPI Garching)


The idm2008 conference has also received support from the Royal Academy of Sciences through its Nobel Institute for Physics,

files Payment form pdf;  files zip archive;  files Poster pdf 

Monday 18 August 2008 toptop

08:00->09:00    Registration (Location: Main entrance of AlbaNova )
Description: Registration for the conference. 

09:00->09:20    Welcome and introduction (Convener: Joakim Edsjö (Fysikum) )
09:00  Welcome and introduction (15') (files Slides pdf  ) Joakim Edsjö (Stockholm University)

09:20->10:00    Dark energy / Dark matter / Cosmology / Overview Dark energy / Dark matter / Cosmology / Overview (Convener: Joakim Edsjö (Stockholm University) )
09:20  Seeing Dark Energy (35'+5') (40') (files Slides pdf  ) Adam Riess (Johns Hopkins University)

The expansion rate and its evolution must be empirically determined for our Universe to reveal its composition, scale, age, and fate. The Hubble Space Telescope is unique in its ability to measure the keystones of cosmic expansion, distant type Ia supernovae and Cepheid variables in their hosts. In 1998, high-redshift SNe Ia provided the first and only direct evidence for an accelerating Universe and the existence of dark energy. More recently, ACS and NICMOS on HST have become tools to calibrate the Hubble diagram of SNe Ia with modern data and to extend its reach to z>1 when cosmic expansion was still decelerating. Now, new measurements from HST of the expansion rate are providing new clues about the nature of the mysterious dark energy.

Coffee break

10:20->11:00    Dark energy / Dark matter / Cosmology / Overview (Convener: Ariel Goobar (Stockholm University) )
10:20  A Cosmic Vision Beyond Einstein (35'+5') (40') (files Slides ppt  ) Eric Linder (University of California, Berkeley)

The acceleration of the cosmic expansion is a fundamental challenge to standard models of particle physics and cosmology. The new physics of dark energy may lie in the nature of gravity (when is gravity no longer attractive?), the quantum vacuum (does nothing weigh something?), or extra dimensions (is nowhere somewhere?). I present an overview of the puzzles and possibilities of dark energy and the means for unraveling them through cosmological probes, as well as comparing a wide variety of "beyond Lambda" models to new data. Next generation experiments will allow us to deeply explore dark energy, dark matter, and gravitation.

11:00->12:10    Indirect searches - gammas (Convener: Ariel Goobar (Stockholm Unversity) )
11:00  Search for dark matter annihilation signals from dwarf spheroidal galaxies with H.E.S.S. (15'+5') (20') (files Slides pdf  ) Christian Farnier (L.P.T.A. Montpellier)

Dwarf spheroidal galaxies are among the most promising targets for the indirect search of WIMP annihilation signal with very high energy (VHE) gamma-ray experiments. The absence of standard astrophysical sources in the dwarf spheroidal galaxies considerably reduces the contamination of a possible exotic signal. The H.E.S.S. array of 4 Imaging Atmospheric Cherenkov Telescopes, situated in the Southern Hemisphere, have already observed some of these objects for energies above few hundred GeV. After applying selection criteria, 18 hours of data are presently available for the analysis of the Sagittarius dwarf galaxy. Results on the velocity-weighted annihilation cross sections for Sagittarius dwarf are given in the frameworks of Supersymmetric and Kaluza-Klein models and plausible dark matter halo models are used.

11:20  Indirect Dark Matter Search with the MAGIC Telescope (20'+5') (25') (files Slides pdf  ) Adrian Biland (ETH Zurich)

The 17m Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) Telescope located on the canary island La Palma already has the lowest energy threshold of all existing Cherenkov Telescopes. Additionally, a second telescope is under construction that will soon allow to significantly increase the sensitivity by using the stereo technique. This makes MAGIC well suited to look for high energy gamma rays coming from e.g. neutralino annihilation in known DM dominated source candidates like the spheroidal dwarf galaxies, or by follow up observations in the adjacent energy band of source candidates like mini-halos or intermediate mass black holes that might be found by the AGILE and GLAST satellites. In case of a positive detection of a DM signal, the absolute cutoff energy will be a very important number. While an absolute energy calibration for Cherenkov telescopes was not possible so far, the recent MAGIC detection of the high-energy cutoff of the pulsed emission from the Crab pulsar will allow to do an absolute energy calibration via crosscalibration with the satellites.

11:45  Gamma-ray searches for dark matter with VERITAS and AGIS (20'+5') (25') (files Slides pdf ppt  ) James Buckley (Washington University)

Ground-based gamma-ray instruments are beginning to provide important constraints on cold dark matter scenarios. Here, I summarize the current observational status of gamma-ray searches for dark matter, and describe prospects for future experiments. While the LHC may detect evidence of new weakly interacting particles, gamma-ray measurements provide the only means for directly connecting these particles to the dark matter by directly measuring the density profile of galactic halos. Moreover, gamma-ray measurements can be used to identify the dark matter candidate by providing detailed spectral measurements of the line and continuum emission which are imprinted with the branching ratios for the different annihilation channels. Unlike direct detection experiments, the cross-section for detection of gamma-rays is intimately related to the decoupling cross section for a thermal relic; at high energies there are tight constraints on the predicted gamma-ray production cross-sections. New ground and space-based instruments such as GLAST, VERITAS and HESS currently have the sensitivity to detect dark matter from some of the strongest sources such as the Galactic center or spiked halos around Galactic intermediate mass black holes. While Whipple, HESS and MAGIC have detected steady VHE emission from the Galactic center, a strong astrophysical background appears to be present, and definitive observations will most likely require new strategies such as observations of nearby dwarf galaxies, or unidentified GLAST sources that could point to structure in the local halo. I describe the current status of gamma-ray measurements of the Galactic center and the dwarf galaxies Draco, Ursa Minor and Wilman I as well as prospects for VERITAS, HESS and MAGIC-II in the GLAST era. I also present detailed calculations of the sensitivity requirements for a future gamma-ray instrument (such as AGIS or CTA) to detect dark matter from a conservative model for the halos of nearby Dwarf galaxies.

Lunch break

13:10->15:05    Indirect searches - gammas (Convener: James Buckley (Washington University) )
13:10  Indirect Dark Matter searches in GLAST era (20'+5') (25') (files Slides pdf  ) JOHANN COHEN-TANUGI (LPTA-CNRS, UNIVERSITÉ MONTPELLIER-II)

The Gamma-Ray Large Area Space Telescope (GLAST), scheduled for launch on June 3 2008, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT), GLAST main instrument, with a wide field of view (>2sr), a large effective area (> 8000 cm2 at 1 GeV), sub-arcminute source localization capabilities, a large energy range (20 MeV - 300GeV) and a good energy resolution (close to 8% at 1GeV), has excellent potential to either discover or to constrain a dark matter signal. The GLAST LAT team pursues complementary searches for signatures of particle dark matter in different search regions and for different scenarios. In this talk I will review these search regions and scenarios.

13:35  A blueprint for detecting supersymmetric dark matter particles in the Galactic halo (20'+5') (25') (files Slides  ) Carlos Frenk (Institute for Computational Cosmology, Durham University)

Based on results from the largest ever simulation of the formation of a galactic halo, I will discuss the optimal strategy required to detect gamma radiation from the annihilation of dark matter particles in the halo of the Mily Way. I will demonstrate that the strongest signal will come from diffuse emission from the halo of the Milky Way, not from known satellites. I will also discuss the implications of this simulation for direct detection.

14:00  Annihilation radiation predictions from N-body simulations (20'+5') (25') (files Slides pdf  ) Mark Vogelsberger (MPA Garching, Germany)

In the beginning of my talk I will present very recent results for the biggest Milky-way sized halo simulation done so far. I will report on dark matter annihilation predictions based on this simulation. The second part of the talk will cover the influence of fine-grained phase-space caustics on the diffuse gamma ray emission. The relevant scales cannot be covered by any state-of-the-art simulation. Therefore I will introduce a new technique resolving the relevant scales and report on the boost of diffuse emission due to these fine-grained caustics for simplified halo models.

14:25  Dark Matter Annihilation in the light of EGRET, HEAT, WMAP, INTEGRAL and ROSAT (15'+5') (20') (files Slides pdf  ) Iris Gebauer (Karlsruhe University)

The excess of diffuse galactic gamma rays above 1 GeV, as observed by the EGRET telescope on the NASA Compton Gamma Ray Observatory, shows all the key features from Dark Matter (DM) annihilation: 1) the energy spectrum of the excess is the same in all sky directions and is consistent with the gamma rays expected for the annihilation of WIMPs with a mass between 50-100 GeV; 2) the intensity distribution of the excess in the sky is used to determine the halo profile, which was found to correspond to the usual profile from N-body simulations with additional substructure in the form of two doughnut-shaped structures at radii of 4 and 13 kpc; 3) recent N-body similations of the tidal disruption of the Canis Major dwarf galaxy show that it is a perfect progenitor of the ringlike Monoceros tidal stream of stars at 13 kpc with ring parameters in excellent agreement with the EGRET data; 4) the mass of the outer ring is so large, that its gravitational effects influence both the gas flaring and the rotation curve of the Milky Way. Both effects are clearly observed in agreement with the DMA interpretation of the EGRET excess; Although the EGRET excess of gamma rays provides an intriguing hint for DMA, its connection to the search for signals in antimatter particles is hampered by the propagation model uncertainties, which determine the local fluxes of charged species for a given source distribution. In the standard propagation models there is no preferred propagation direction. In such models the Galaxy acts as a large storage box for charged particles, thus leading to a strong enhancement of the particle fluxes from the halo. However, present data from INTEGRAL and ROSAT strongly suggest that convection dominates over diffusion at low energies and in the source region, implying that particles produced by DMA in the halo have little probability to arrive at the detector. We present an anisotropic convection-dominated model for Cosmic Ray transport and show that the EGRET gamma ray excess, the HEAT positron excess, the INTEGRAL positron annihilation signal, the PAMELA antiproton fluxes and the WMAP-haze are consistent with each other in such models.

14:45  Dark matter annihilation signals -- the importance of radiative corrections (15'+5') (20') (files Slides pdf  ) Torsten Bringmann (SU Fysikum)

Being able to safely distinguish astrophysical from potential dark matter (DM) annihilation signals is of utmost importance for indirect DM searches. For this, one has in general to rely on distinctive -- and unique -- spectral signatures to look for. In this talk, I point out that internal bremsstrahlung, which unavoidably accompanies charged annihilation products, provides such a signature. In fact, it often even dominates the gamma-ray spectrum expected from DM annihilations, demonstrating that radiative corrections can significantly exceed naive expectations; for a large part of the WIMP parameter space internal bremsstrahlung, furthermore, turns out to be more important for indirect DM searches than the traditionally looked-for line signals. The gamma-ray contributions reported here may therefore be of great importance for upcoming observatories like the soon to be launched GLAST sattellite or the new generation of Air Cherenkov Telescopes. I illustrate in some detail the situation for neutralino DM in mSUGRA and the MSSM, but also briefly mention other DM candidates such as the lightest Kaluza-Klein particle appearing in models with universal extra dimensions. Finally, I comment on the potential of using these signatures to distinguish between different DM candidates and on the importance of radiative corrections for other annihilation channels, in particular positrons.

Coffe break

15:25->16:05    Dark energy / Dark matter / Cosmology / Overview (Convener: Jan Conrad (Stockholm University) )
15:25  Mapping dark matter with galaxies, CMB and 21 cm tomography (35'+5') (40') (files Slides pdf  ) Max Tegmark (MIT)

16:05->17:35    Connections with accelerators (Convener: Jan Conrad (Stockholm Unversity) )
16:05  R-parity conserving SUSY searches in ATLAS (25'+5') (30') (files Slides pdf  ) Børge Kile Gjelsten (University of Oslo)
16:35  Measurement of Dark Matter Content at the LHC (15'+5') (20') (files Slides pdf  ) Bhaskar Duta Dutta (Texas A&M University)

Recent cosmological observations have introduced tremendous constraint on supersymmetry models. The minimal supergravity (mSUGRA) model explains the observed dark matter content of the universe and requires stau-neutralino co-annihilation mechanism in the early universe for a large region of supersymmetry parameter space. This co-annihilation region is characterized by a small mass difference (~5-15 GeV) between the lightest stau and the lightest neutralino. An accurate measurement of the small mass difference at a collider is crucial to confirm the co-annihilation mechanism. We show that from measurements at the LHC it is possible to confirm this mechanism and using these measurements one can predict the dark matter relic density with an uncertainty of 6% with 30 fb-1 of data. This is possible by introducing measurements involving b-quark jets to determine the SUGRA parameters A0 and tan(beta). We measure all the mSUGRA parameters with high accuracy and our methods provide precision mass measurements of the gauginos, squark, and lighter stau without the mSUGRA assumption. This talk is based on the following papers: arXiv:0802.2968 (to appear in Phys Rev Lett); Phys.Lett.B649:73-82,2007, Phys.Lett.B639:46-53,2006.

16:55  Combining accelerators with Dark Matter Direct Detection (15'+5') (20') (files Slides pdf  ) Mattia Fornasa (University of Padova & Institut d'Astrophysique de Paris)

A bayesian approach seems to be very efficient in the scan of the 24-dimesional parameter space of a Minimal SuperSymmetry Model: in fact, differently from a grid scan, experimental constrains and data can be easily introduce into the analysis. For example, a supposed detection of new particles at colliders will provide a collection of measurements able to guide us to the region in the SUSY parameter space that best fit the data. This technique can easily be extended to include results from an assumed detection in an experiment of Dark Matter Direct Detection so that, in the hypothesis that DM is made of the lightest neutralino, from the combination of accelerator observables and measurements from DM searches, the SUSY parameters can be further constrained. There results can be used to obtain informations on the DM candidate, testing common assumptions about, e.g., the local DM density and the average velocity. I will briefly introduce the basis of the bayesian analysis and present some preliminary results.

17:15  Kaluza-Klein Dark Matter: Direct Detection vis-a-vis LHC (15'+5') (20') (files Slides pdf  ) Sebastian Arrenberg (Physics Institute, University of Zürich)

We explore the phenomenology of Kaluza-Klein (KK) dark matter in very general models with universal extra dimensions (UEDs), emphasizing the complementarity between high-energy colliders and dark matter direct detection experiments. In models with relatively small mass splittings between the dark matter candidate and the rest of the (colored) spectrum, the collider sensitivity is diminished, but direct detection rates are enhanced. UEDs provide a natural framework for such mass degeneracies. We consider both 5-dimensional and 6-dimensional non-minimal UED models, and discuss the detection prospects for various KK dark matter candidates: the KK photon, the KK Z-boson, the KK Higgs boson (all 5D) and the spinless KK photon (6D). We combine collider limits such as electroweak precision data and expected LHC reach, with cosmological constraints from WMAP, and the sensitivity of current or planned direct detection experiments. Allowing for general mass splittings, we show that neither colliders, nor direct detection experiments by themselves can explore all of the relevant KK dark matter parameter space. Nevertheless, they probe different parameter space regions, and the combination of the two types of constraints can be quite powerful. For example, in the case of the KK photon in 5D UEDs the relevant parameter space will be almost completely covered by the combined LHC and direct detection sensitivities expected in the near future.

18:00->20:00    Poster session (Location: Outside Restaurant Entré )
18:00  MICROMEGAS for Rare Event Searches (20') Theopisti Dafni (University of Zaragoza)

Recently, micropattern detectors and in particular Micromegas are receiving much attention from the community of rare event searches, like dark matter (axion or WIMPs) searches or double beta decay. The main features that make these detectors rather promising for this field of research will be summarised and the latests results on the development of Micromegas towards this direction will be shown;on one hand,in the context of axion searches in the CAST experiment, the development of several new Micromegas detectors using a novel manufacturing technique (Microbulk) on the other, results like the energy resolution measurements at high energy and at high pressure preformed with Micromegas, confirming the interest of their application to double beta decay searches.

18:00  7Li solar axions: preliminary results and feasibility studies (20') Riccardo Cerulli (INFN-LNGS)

Sun could be an intensive source of axions. The energy spectrum of Solar axions would consist of the continuous part generated via the Primakoff effect, and quasi-monochromatic lines related with deexcitation of excited levels of nuclides present in Sun through magnetic nuclear transitions. These levels can be thermally excited because of high temperature in the solar core, or can be populated in nuclear reactions. In a deexcitation process, axions could be emitted instead of  quanta with some probability related to the axion mass. Feasibility studies on a search for 7Li solar axion have been carried out by considering the data collected with a LiF powder in a low background HP Ge detector at LNGS. It has allowed to set limit on the 7Li solar axion mass of 13.9 keV, better than the previously available one. The improvement is important because it closes the existing possible window between 16.0 keV and 14.4 keV, which is the energy of the next potential source of quasi-monochromatic solar axions from 57Fe. Improved results would be achieved with LiF(W) crystal which – in contrast with the LiF powder – does not show a relatively high contamination by U/Th chains. The potential backgrounds and the reachable sensitivity of this future experiment will be also discussed.

18:00  Search for solar axions with the CDMS-II experiment (20') Tobias Bruch (University of Zurich, Physics Institute)

T. Bruch for the CDMS collaboration The CDMS-II experiment operates 19 germanium detectors with a mass of 250g each in a very low background environment. Originally designed for the search for Dark Matter the experiment can also detect solar axions by Primakov conversion. The Bragg condition for x-ray momentum transfer in a crystal allows for coherent amplification of the Primakov process. Since the orientation of the crystal lattice with respect to the sun changes with daytime a unique pattern in time and energy of solar axion conversions is expected. The low background $\sim$1 cpd/(kg keV) and knowledge of the exact orientation of all three crystal axes with respect to the sun make the CDMS-II experiment very sensitive for solar axions. In contrast to helioscopes, also the high mass region around 1 eV can be probed effectively. The alternating orientations of the individual crystals in the experimental setup provide different patterns of solar axion conversion, making a false positive result extremely unlikely. The results of the analysis of 286 kgd of exposure will be presented.

18:00  Search of axions from a nuclear power reactor with a high-purity germanium detector (20') (files Poster pdf  ) Henry Wong (Academia Sinica)

A search of axions produced in nuclear transitions was performed at the Kuo- Sheng Nuclear Power Station with a high-purity germanium detector of mass 1.06 kg at a distance of 28 m from the 2.9 GW reactor core [1]. The expected experimental signatures were mono-energetic lines produced by their Primakoff or Compton conversions at the detector. Based on 459.0/96.3 days of Reactor ON/OFF data, no evidence of axion emissions were observed and constraints on the couplings g_agg and g_aee versus axion mass m_a within the framework of invisible axion models were placed. The KSVZ and DFSZ models can be excluded for 10^4 eV < m _a < 10^6 eV. Model-independent constraints on (g_agg X g_aNN) < 7.7X10^{-9} GeV^{-1} for m_a < 10^5 eV and (g_aee X g_aNN) < 1.3X10^{-10} for m_a < 10^6 eV at 90% confidence level were derived. This experimental approach provides a unique probe for axion mass at the keV-MeV range not accessible to the other techniques. Reference: 1. H.M. Chang et al., TEXONO Coll., Phys. Rev. D 75, 052004 (2007).

18:00  A Standard Axion B136 with Mass of 136 keV/c² as a Dark Matter Candidate. ID 250 (20') Jacques Steyaert (Retired from UCLouvain)

S.Weinberg* and F.Wilczek(1978) calculated a "standard" axion with mass around 100 keV, after initial proposal from Peccei and Quinn(1977). [*69 keV/sin(2 alpha), alpha about= 15° if we are right with 136 keV/c²] We performed an experiment where gamma rays from Tantalum were converted into a "Boson" by Primakoff Effect (PE). That boson B136 decayed into (two) 68 keV gamma rays toward a Ge(Li) detector (no Lead shilding). Curiously, these gamma rays were increasing in intensity with distance up to 2 m probably by an enhanced decay of the boson (one gamma in, many out) (or exponential increase from rolling tachyon). At 4 m, the intensity was strongly suppressed. Unexpectedly, the boson seems also to decay into one or two"fundamental momentum" (fm) with 418 keV/c of total impulsion. Up to now no coincidence experiment was performed that would confirm the two gamma decay of B136. If it is confirmed, it could be a standard axion. The fm was discovered by a broad signal at 170 keV (Sir Wilkinson's bump) from fm absorption onto an electron, the position of the broad peak being independent of the initial gamma ray energy with a threshold at about 136 keV. To be a candidate for Dark Matter (DM), B136 has to be produced in the core of stars, from nuclear gamma rays onto heavy metals (PE) and be diffused outside the stars as "bosonic bubbles", where fm from decay is absorbed by a proton at rest, giving it a sudden velocity of 133 km/s (93 eV, 1 MK) or multiple of it (stellar wind). This could be called the Terletskii or tachyoelectric effect: fm momentum and energy are completely transferred to the proton; this is contrary to the photoelectric effect that cannot take place in vacuum. The halo of a galaxy being full of fm , a slow proton at the outskirt could reach a velocity of 133 km/s, like in M33, or multiple of it, if fm are successively aligned: 266, 400 km/s (about the maximum of a Rotational Curve); 188 km/s is obtained if fm are perpendicular in direction. Possible DM decay would put the galaxy in motion (Merrygoround) and push Coronal Mass Ejections and Flares. [Hergig Haro Objects have a bow shock at 1 MK and velocities about 120-160 km/s : is it the reverse of corona heating, but same origin ?] Solving the DM problem, could solve other astrophysical problems: the successive fm absorptions are a potential accelerator for cosmic rays; temperature 1 MK of galaxy clusters; help solving the solar coronal problem. B136 is maybe not the only DM component (Jain, Singh 7 and 19 MeV "axion") but a good possible candidate. [Di Lella and Zioutas pointed out a comprehensive view of unexpected astrophysical X-ray observations from many sources (100 eV, 1 MK) (CERN-EP/2002-038 ) probably related to our B136] [Ioffe Russian "deamons" could be related to a tachyon interacting with inner metal layer of the photomultiplier] [HDMS 32 keV signal, maybe a genuine DM one, attributed to 210Pb partially detected, could be due to B136->68->34->17->8.5->4.25 ... keV "degradation".

18:00  Astrophysical tests of mirror dark matter (20') Paolo Ciarcelluti (University of Liège, Belgium)

Mirror matter is a self-collisional dark matter candidate. If exact mirror parity is a conserved symmetry of the nature, there could exist a parallel hidden (mirror) sector of the Universe which has the same kind of particles and the same physical laws of our (visible) sector. The two sectors interact each other only via gravity, therefore mirror matter is naturally "dark". This candidate is so far compatible with all the experiments, and in particular it can explain the recent DAMA/LIBRA results. The most promising way to test this dark matter candidate is to look at its astrophysical signatures, as Big Bang nucleosynthesis (BBN), primordial structure formation and evolution, cosmic microwave background (CMB) and large scale structure power spectra, dark stellar structures (microlensing events). In particular, mirror matter could avoid the discrepancy between the numbers of extra neutrino families computed at BBN and CMB formation epochs. In this talk I show the state of the research in all these topics.

18:00  Searches for Hyperbolic Extra Dimensions at the LHC (20') Henrik Melbéus (Department of theoretical physics, KTH)

We investigate a model of large extra dimensions where the internal space has the geometry of a hyperbolic disc. Compared with the ADD model, this model provides a more satisfactory solution to the hierarchy problem between the electroweak scale and the Planck scale, and it also avoids constraints from astrophysics. Since there is no known analytic form of the Kaluza-Klein spectrum for our choice of geometry, we obtain a spectrum based on a combination of approximations and numerical computations. We study the possible signatures of our model for hadron colliders, especially the LHC, where the most important processes are the production of a graviton together with a hadronic jet or a photon. We find that for the case of hadronic jet production, it is possible to obtain relatively strong signals, while for the case of photon production, this is much more difficult.

18:00  Nuclear scattering of dark matter with an excited state (20') (files Poster pdf  ) Tracy Slatyer (Harvard University)

We consider the nuclear scattering cross-section and direct detection prospects for the eXciting Dark Matter (XDM) model. In XDM, the WIMPs couple to the visible sector only via an intermediate light scalar which mixes with the Higgs: this leads to a suppression in the nuclear scattering cross-section relative to models in which the WIMPs couple to the Higgs directly. We estimate this suppression factor to be at least 10^(-5). The elastic nuclear scattering cross- section for XDM can also be calculated directly: for XDM coupled to the Higgs sector of the MSSM, we find a cross-section in the order of 4 x 10^(-13) pb in the decoupling limit, which is not within the range of any near-term direct detection experiments. The cross-section may be enhanced in certain regions of the MSSM parameter space.

18:00  Development of wavelength shifters for the ArDM Argon Dark Matter detector (20') (files Poster pdf  ) Konstantinos Mavrokoridis (University of Sheffield)

The Argon Dark Matter (ArDM) is a 1-ton two phase liquid/gaseous argon scintillation/ionisation WIMP detector. The primary VUV scintillation light of argon (wavelength 128 nm) needs to be shifted to visible light in order to match the sensitivity range of the photomultiplier tubes. We discuss results from the development and optimization of wavelength shifters based on the organic scintillator tetraphenyl butadiene (TPB).

18:00  Charge identification in PAMELA: preliminary results on light nuclei. (20') Rita Carbone (INFN sez. di Napoli)

The study of the light-nuclei component of the cosmic radiation is strictly connected to a better understanding of the propagation properties, which has great importance for the study of signatures of new physics in CRs. For example, indirect signals of dark matter pairs annihilating in the halo of our Galaxy could be found in antiproton, antideuteron or positron CRs but this research is limited by the uncertainties in the propagation parameters and fluxes of charged particles located in the whole diffusive halo. The PAMELA experiment will contribute to this issue measuring light nuclei fluxes and ratios with good accuracy, also in some unexplorated energy range. Some preliminary results on the identification capability of PAMELA subdetectors for nuclei up to Oxygen will be presented in this work.

18:00  The OSER project (20') marc moniez (IN2P3-CNRS)

Cool molecular hydrogen H2 may be the ultimate possible constituent to the Milky-Way baryonic hidden matter. I will describe a new way to search for such transparent matter in the Galactic discs and halo, through its diffractive and refractive effects on the light of background stars. I will show that the relative configuration of the sources and the hypothetic hydrogen clouds is such that the expected scintillation contrast and characteristic time make possible a detection at the optical wavelengths with the available technology. Results from simulations and preliminary results from a test performed with the ESO-NTT telescope will be presented and discussed.

Welcome reception and poster session

Tuesday 19 August 2008 toptop

08:30->10:10    Direct detection - experiments (Convener: Neil Spooner (University of Sheffield) )
08:30  The PICASSO Dark Matter Search (15'+5') (20') (files Slides pdf  ) Anna Davour (Queen's University)

PICASSO is an array of bubble detectors constructed to search for spin dependent interactions of weakly interacting massive particles. The bubble detectors are similar to those used in neutron dosimetry: superheated droplets of fluorocarbon (C4F10) are suspended in a polymerized gel, where a nucleus recoiling from the elastic scattering of a WIMP triggers the boiling of the superheated liquid. The explosive expansion of a droplet to a bubble will induce an acoustic wave in the gel which is picked up with piezoelectric sensors. The PICASSO collaboration has developed large volume bubble detectors of 4.5 litres. The performance of these detectors has been evaluated with several methods. The detectors are installed at SNOLAB, located at a depth of 2070 meters in the Creighton mine in Sudbury. The completed setup contains 32 detectors with a combined active mass of 2.6 kg. New exclusion limits on the WIMP cross section will be presented, based on data from the first of the large detectors.

08:50  XMASS experiment (15'+5') (20') (files Slides pdf ppt  ) Yoichiro Suzuki (Kamioka Observatory, Institute for Cosmic Ray Research, the University of Tokyo)

A direct dark matter search experiment, XMASS, uses 800kg of liquid xenon and its fiducial mass is 100kg. It uses newly developed background PMTs and makes use of self-sheilding mathod to reduce external backgrounds. The backgroud rate in the signal region is expected to be 10^-4 /kg/keV/day and it will achieve the experimental sensitivity of 10^-45 cm^2 for the spin independet interactions for the dark matter mass of around 100GeV. The new underground cavity to house the experiment has completed in February this year and the construction of the XMASS experiment will finish by summer, 2009. We will discuss the status of the XMASS experiment.

09:10  The WArP Dark Matter Search (15'+5') (20') (files Slides pdf  ) Giuliana Fiorillo (Università degli Studi di napoli Federico II)

WArP is a graded programme to search for Wimp dark matter with liquid argon. The WArP 100l detector is being assembled and should start data taking in the next few months. We expect to increase the sensitivity of about a factor 100 with respect to the 2.3 liters protoype, which has been operational since 2005, allowing for an intense R&D programme that has given us insight to crucial LAr properties. The current status of the experiment and the main results obtained with the prototype will be reviewed.

09:30  Ultra Low Temperature Dark Matter Detector with 30% of Non-paired Neutrons. (15'+5') (20') (files Slides ppt  ) Yury Bunkov (Institut Neel, CNRS/UJF, Grenoble, France)

A direct Dark Matter detector of a new type, developed in the framework of the “ULTIMA” project, is ready to be installed at the Canfranc underground laboratory. It is based on properties of superfluid 3He at the limit of extremely low temperatures of about 0.1 mK. At these temperatures all 3He atoms are condensed in a coherent superfluid state with a heat capacity of about 10 keV per gram. On the prototype of this detector, we have achieved the sensitivity of 1keV events. We have developed new techniques of electron/nuclear recoil discrimination on the basis of pulse shape analysis. The main advantage of our detector is the 30% concentration of non-paired neutrons in 3He nuclei, which makes it a premier material for testing the axially interacting Dark Matter. The quantum coherence of superfluid 3He can be also interesting in order to probe some exotic types of Dark Matter. The experimentally measured surface limits for specific nuclear-interacting form of Dark Matter will be presented.

09:50  DEAP/CLEAN experiment at SNOLAB (15'+5') (20') (files Slides pdf  ) Mark Boulay (Queen's University)

The DEAP/CLEAN experiment will search for dark matter particle interactions on liquid argon at SNOLAB. The first generation detector (DEAP-1) with a 7-kg liquid argon target mass is currently operating underground at SNOLAB and an overview of that experiment, including pulse-shape discrimination (PSD) results for reducing β/γ backgrounds, and the status of data collection at SNOLAB, will be presented. A larger detector (DEAP/CLEAN- 3600) containing a total of 3600 kg of liquid argon is currently being designed, with a target sensitivity to spin- independent scattering on nucleons of 10-46 cm2, several hundred times more sensitive than current dark matter experiments. Initial construction activities are planned for SNOLAB beginning in 2008. The design and construction status of DEAP/CLEAN-3600 will be presented.

08:30->10:10    Theoretical models and related topics (Convener: Aharon Davidson (Ben Gurion University) ) (Location: FB53 )
08:30  Toward a viable dark matter candidate without invoking SUSY (15'+5') (20') (files Slides ppt  ) (Location: FB42 ) Andrew Beckwith (FNAL)

Using the recent results of K. Meissner and H. Nicolai in their article , “ Neutrinos , Axion and Conformal Symmetry” (arXIV 0803.2814v2) , we can and do refer to their derived conditions for which the classically conformable Lagrangian may be built up to eliminate both the Higgs and the necessity of SUSY for a viable axion candidate. We claim that this elimination of SUSY will, provide conditions to check if or not there are more than three generations of fermions. Note that the Standard Model has three generations of fermions. If there are shown to be more than three, then the Standard Model is incorrect and needs to be adjusted. As an example, calling for a fourth sterile neutrino, for example, constitutes an extension of the current Standard Model. We also claim that the generation of axions and the known datum that dark matter existed before dark energy will allow us to identify , through axion and neutrio physics conditions for the generation of dark matter in early universe nucleation

08:50  Gravitino Dark Matter with Sneutrino NLSP in NUHM (15'+5') (20') (files Slides pdf  ) (Location: FB42 ) Yudi Santoso (IPPP, University of Durham, UK)

I am going to talk about gravitino dark matter with sneutrino NLSP scenario in the Non-Universal Higgs Masses (NUHM) model. Gravitino is a candidate for dark matter in supergravity theories, with very weak interaction. The phenomenological signature of this scenario depends on the next lightest supersymmetric particle which is metastable. Among the possible NLSP, sneutrino had been shown to have distinct phenomenology. I will show how sneutrino NLSP can be realized in NUHM model, and I will proceed with discussing the phenomenology.

09:10  Superheavy neutralinos as dark matter particles (15'+5') (20') (files Slides pdf  ) (Location: FB42 ) Marius Solberg (NTNU)

We propose the lightest supersymmetric particle (LSP) as a well-suited candidate for superheavy dark matter. The mass $m_\chi$ of the LSP should be above $3\times 10^{11}\,{\rm GeV}$, so that gravitational interactions at the end of inflation can produce it with the correct abundance, $\Omega_\chi h^2 \sim 0.1$. Weak interactions remain perturbative despite the large mass hierarchy, $m_\chi\gg m_Z$, because of the special decoupling properties of supersymmetry. As a result the model is predictive and we discuss elastic scattering of neutralinos on light fermions, self-scatterings and briefly annihilations within this scheme.

09:30  Implications of Yukawa unification and WMAP dark matter in the observation of flavor-violating signals. (15'+5') (20') (files Slides pdf  ) (Location: FB42 ) Mario E. Gomez (Universidad de Huelva)

We study Yukawa couplings compatibles with SUSY-GUT's based on SU(5) symmetries and neutrino flavor oscillations. By impossing WMAP cosmological constraints to the pattern of soft terms determined by the SU(5) symmetry, we analyze the possibility of observing signals of lepton flavor violating decays of sleptons at the LHC.

Coffee break

10:30->12:10    Direct detection - experiments (Convener: Lars Bergström (Stockholm Unversity) )
10:30  The Cryogenic Dark Matter Search (20'+5') (25') (files Slides pdf ppt  ) Jeter Hall (Fermilab)

The Cryogenic Dark Matter Search (CDMS II) utilizes high purity germanium particle detectors to search for Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs). We use the ionization and athermal phonons from particle interactions to separate the largely electromagnetic backgrounds from candidate WIMP-nucleon scattering in our detectors. We report on the latest results which reach a sensitivity of 4.6 x 10^-44 cm^2 for the WIMP-nucleon spin- independent cross section at a WIMP mass of 60 GeV/c^2. We also report on the status of the experiment and comment on the SuperCDMS experiment which is focused on increasing the sensitivity of this technology.

10:55  Status of the XENON100 Dark Matter Experiment at LNGS (20'+5') (25') (files Slides pdf  ) Elena Aprile (Columbia University)

The XENON100 experiment aims to detect cold dark matter particles via their elastic collisions with xenon nuclei. An ultra-low background, two-phase time projection chamber with a total of 170 kg of xenon (70 kg in the target region and 100 kg in the active shield) has been installed at the Gran Sasso Underground Laboratory and is currently in commissioning phase. I will review the design and performance of the detector and its associated systems, based on initial calibration runs.

11:20  COUPP: EARLY RESULTS AND FUTURE DIRECTION (20'+5') (25') (files Slides pdf  ) Peter Cooper (Fermi National Accelerator Laboratory)

For decades, the bubble chamber was the primary particle detection technique for high-energy physics. We demonstrate how an ultra-clean, room-temperature bubble chamber can be adapted as a direct dark matter detector. A chamber containing superheated CF3I is maximally sensitive to both spin-dependent and - independent Weakly Interacting Massive Particle (WIMP) interactions. A high inherent insensitivity to typical backgrounds affecting other WIMP searches has been demonstrated in conditions leading to detection of low-energy, hence WIMP-like, nuclear recoils. Improved limits on the spin-dependent WIMP-proton scattering cross-section have been achieved with a 2kg chamber, excluding one explanation for a recent claim of discovery. Here we also outline plans for future chambers of greater mass and better sensitivity.

11:45  First results from DAMA/LIBRA (20'+5') (25') (files Slides ppt  ) Pierluigi BELLI (INFN Sezione Roma Tor Vergata)

The highly radiopure about 250 kg NaI(Tl) DAMA/LIBRA set-up is running at the Gran Sasso National Laboratory of the I.N.F.N.. First results exploiting the model independent annual modulation signature for Dark Matter particles in the galactic halo are presented (exposure of 0.53 ton x yr). The DAMA/LIBRA data confirm the evidence for the presence of Dark Matter particles in the galactic halo as observed by the former DAMA/NaI experiment. The combined analysis of the data of the two experiments (total exposure 0.82 ton x yr) gives a C.L. at 8.2 sigma.

Lunch break

13:05->14:05    Direct detection - experiments (Convener: Elena Aprile (Columbia University) )
13:05  Backgrounds and Sensitivity Expectations for XENON100 (15'+5') (20') (files Slides pdf  ) Laura Baudis Baudis (University of Zurich)

The XENON100 experiment aims to detect cold dark matter particles via their elastic collisions with xenon nuclei. An ultra-low background, two-phase time projection chamber with a total of 170 kg of xenon (70 kg in the active region) has been installed at the Gran Sasso Underground Laboratory and is currently in commissioning phase. We present background predictions based on Monte Carlo simulations with input from screening of detector and shield materials. We show the expected sensitivity for spin-independent and spin- dependent cross sections on nucleons and compare with theoretical predictions from physics beyond the Standard Model.

13:25  LUX - Large Underground Xenon Dark Matter Experiment - Report on Design, Construction and Detector Testing (15'+5') (20') (files Slides pdf  ) Richard Gaitskell (Brown University)

The new 350 kg liquid xenon TPC detector, LUX [ ], has begun construction, and will be deployed in 2008, at Sanford Underground Lab (SUSEL). The detector will be located in a 250 tonne watershield at the 4850 ft level of the Homestake Mine, South Dakota, in the old Davis Cavern. Following commissioning in 2008, LUX will begin a dark matter search run in early 2009. The goal for the experiment will be a search sensitivity (for spin independent coupled WIMPs) which is two orders of magnitude better than the current best limits [ ]. I will discuss critical aspects of the design, and construction of the LUX experiment. I will report the latest results from the testing of the detector, and will also report on the overall construction project progress. I will also discuss the factors affecting the physics reach possible with, and the design challenges associated with, the scale up to 3 tonne, and 20 tonne detectors.

13:45  Projected backgrounds and sensitivity for the LUX dark matter experiment. (15'+5') (20') (files Slides pdf  ) Daniel McKinsey (Yale University)

The LUX experiment will search for Weakly Interacting Massive Particles (WIMPs) using a liquid Xenon time projection chamber. Simultaneous measurement of ionization and scintillation allows for 3D position reconstruction, with a nuclear recoil energy threshold as low as 4.5 keV. The ratio of ionization to scintillation allows event by event discrimination between nuclear and electronic recoils, and self-shielding provides significant additional gamma ray background reduction. LUX will detect WIMP dark matter, or exclude its spin-independent cross section (per nucleon) down to a level of 7E-46 cm^2. Based on above-ground calibrations and data from the XENON10 experiment, LUX is expected to reject up to 99.9% of the dominant electron- recoil background at detector threshold (4.5 keVr), with 50% acceptance for nuclear recoils. This talk will discuss expected gamma ray, beta, and neutron backgrounds and the projected sensitivity of the LUX experiment. Also discussed will be the dependence of the LUX sensitivity on the liquid Xenon nuclear recoil scintillation yield.

14:05->15:05    Direct detection - phenomenology/theory (Convener: Elena Aprile (Columbia University) )
14:05  Reconciling DAMA with Inelastic Neutralino Dark Matter; Predictions for Ge, Xe, I and W. (15'+5') (20') (files Slides ppt  ) Neal Weiner (New York University)

The inelastic dark matter model, in which WIMP-nucleus scatterings occur via transition to an excited WIMP state ~ 100 keV above the ground state, modify the relative sensitivities of various dark matter direct detection experiments. In this model, the DAMA annual modulation signature can arise consistent with presently null results at CDMS-Soudan, XENON10, CRESST, and KIMS. The neutralino, in an R- symmetric SUSY model, can provide a natural example of such a model. We review the status of the relative experiments and their sensitivities, and make predictions for upcoming experiments. In particular, we note that the model predicts highly suppressed signals at low energy, with most nuclear recoil events typically occuring between 20 to 45 keV at xenon and iodine experiments.

14:25  Determining the WIMP mass from a single direct detection experiment (15'+5') (20') (files Slides pdf  ) Anne Green (University of Nottingham)

The energy spectrum of nuclear recoils in Weakly Interacting Massive Particle (WIMP) direct detection experiments depends on the underlying WIMP mass (strongly for light WIMPs, weakly for heavy WIMPs). We discuss how the accuracy with which the WIMP mass could be determined by a single direct detection experiment depends on the detector configuration and the WIMP properties. In particular we examine the effects of varying the underlying WIMP mass and cross-section, the detector target nucleus, exposure, energy threshold and maximum energy, the local circular speed and the background event rate and spectrum.

14:45  Constraining the Spin-Independent WIMP-Nucleon Coupling from Direct Dark Matter Detection Data (15'+5') (20') (files Slides pdf  ) Chung-Lin Shan (DMRC, Seoul National University, Korea)

Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Cold Dark Matter. For understanding the properties of WIMPs and identifying them among new particles produced at colliders (hopefully in the near future), determinations of their mass and their couplings on nucleons from direct Dark Matter detection experiments are essential. Based on our method for determining the WIMP mass model-independently from experimental data, we present a way to also estimate the spin-independent (SI) WIMP-nucleon coupling by using measured recoil energies directly. This method is independent of the as yet unknown velocity distribution of halo WIMPs. In spite of the uncertainty of the local WIMP density, at least an upper limit on the SI WIMP-nucleon coupling could be given, once two (or more) detectors with different target nuclei obtain positive signals. In a background- free environment, for a WIMP mass of 100 GeV its SI coupling on nucleons could in principle be determined with an error of O(30\%) with only 50 events from each experiment.

Coffee break

15:25->16:45    Direct detection - experiments (Convener: Jeter Hall (Fermilab) )
15:25  EURECA – the Future of Cryogenic Dark Matter Detection in Europe (15'+5') (20') (files Slides pdf  ) Hans Kraus (University of Oxford)

The European Underground Rare Event Calorimeter Array (EURECA) will be an astro-particle physics facility in the Laboratoire Souterrain de Modane, aiming to directly detect galactic dark matter. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effort on cryogenic detector research in Europe into a single facility. The aim is to explore scalar cross sections in the 10E-9 – 10E-10 picobarn region with a target mass of up to one tonne. A major advantage of EURECA is the planned use of more that just one target material (multi target experiment for WIMP identification).

15:45  EDELWEISS direct dark matter search. (15'+5') (20') (files Slides pdf  ) xavier defay (CSNSM)

EDELWEISS is a direct dark matter search located in the low radioactivity environment of the Modane Underground Laboratory. The experiment uses Ge detectors at very low temperature in order to identify eventual rare nuclear recoils induced by elastic scattering of WIMPs from our galactic halo. The commissioning of the second phase of the experiment, involving more than 7 kg of Ge detector, has been completed in 2007. These ionization/heat detectors allow an event by event electronic/nuclear recoil discrimination. A complementary active rejection of surface events is required to achieve the physics goals of the present phase. We present preliminary results of two types of detectors with active rejection (detector with NbSi thin films thermometer and a new type of bolometer with interdigitized electrodes for the charge collection).

16:05  The CRESST Dark Matter Search (15'+5') (20') (files Slides ppt  ) Federica Petricca (Max-Planck-Institut fuer Physik)

The CRESST-II direct Dark Matter search is located in the Gran Sasso underground laboratories. CaWO4 crystals have been used as scintillating targets for WIMP interactions. They are operated as cryogenic calorimeters in combination with a second cryogenic detector used to measure the scintillation light produced in the target crystal. For each particle interaction, the combination of phonon and light signals enables an event by event discrimination which allows distinguishing known particles (alphas, betas, gammas, neutrons) from the expected signal of weakly interacting massive particles (WIMPs). After a major upgrade of the setup, the experiment has been successfully commissioned and data from the commissioning phase are presented here. Combining the data collected with the two detector modules running in this phase with the data from one single module obtained during the previous prototyping run, the experiment could already place a limit of 5.3×10-7 pb for the spin independent scattering cross section for WIMPs of 60 GeV/c2 mass. Finally a brief report on the status of the ongoing data taking phase with 17 detector modules installed will be given.

16:25  ZEPLIN-III: The First Science Run (15'+5') (20') (files Slides ppt  ) Tim Sumner (Imperial College London)

ZEPLIN-III is a two-phase xenon direct dark matter detector operating in a deep underground laboratory at Boulby in the UK. Data will be presented from its first science run carried out between February 27th and May 22nd 2008.

Reception in the City Hall

Wednesday 20 August 2008 toptop

08:30->09:50    Direct detection - experiments (Convener: Richard Gaitskell (Brown University) )
08:30  Sapphire, BGO and LiF scintillating bolometers developed for dark matter experiments (15'+5') (20') (files Slides pdf  ) Ysrael Richard Ortigoza Paredes (University of Zaragoza, Spain)

ROSEBUD (Rare Objects Search with Bolometers UndergrounD) is a collaboration between the Institute d’Astrophysique Spatiale (IAS, Orsay, France) and the University of Zaragoza (Zaragoza, Spain), focused on the development of scintillating bolometers for WIMP (Weakly Interacting Massive Particles) searches. In this work we present the results of tests performed with three small scintillating bolometers (50 g sapphire, 46 g BGO and 33 g LiF) used simultaneously in the same set-up and external background conditions at the Canfranc Underground Laboratory. Sapphire and BGO have been studied as possible dark matter targets. We analyze their particle discrimination capability with special stress in the discrimination between nuclear recoils and beta/gamma background events at low energy. Nuclear recoil spectra obtained simultaneously in both detectors are shown and discussed. BGO and LiF can also be used to monitor background. The BGO bolometer has been used as a gamma-ray spectrometer (profiting from its high atomic number content) to analyze and reduce beta/gamma background of the three detectors. The LiF scintillating bolometer can be applied through the 6Li (n, alpha)t reaction to monitor neutron flux inside the experimental set-up.

08:50  Directional Dark Matter Search with Nuclear Emulsion (15'+5') (20') (files Slides pdf  ) Tatsuhiro Naka (Nagoya University , Japan)

Directional detection of WIMP is very important, because direction of WIMP wind might have daily modulation. So this way can be confirmed WIMP signal high reliabirity than using annual modulation by the detector having derectional sensitivity. We will experiment dark matter serch with Nuclear Emulsion. Nuclear Emulsion has high density and high resolution. So, It is possible to be large mass detector and to search of WIMP by direction of nuclear recoil track . This detector is very unique and strong for dark matter search. Now, we are doing R&D of detector to detect the WIMP. We developed very high resolution nuclear emulsion for dark matter search, and comfirmed it have ability to detect the WIMP signal. In this talk, I will talk about status R&D result the method of readout track and background rejection, future plan and prospect.

09:10  Direction-sensitive direct dark matter search; NEWAGE (15'+5') (20') (files Slides pdf  ) Hironobu Nishimura (Kyoto University)

NEWAGE is a project of direction-sensitive direct dark matter search experiments. We developed a three-dimensional gaseous tracking device with an effective volume of 23x28x30 cm^3, and performed a direction-sensitive dark matter search in a surface laboratory. By using 150 Torr carbon-tetrafluoride (CF4gas), we obtained a sky map drawn with the recoil directions of the carbon and fluorine nuclei, and set the first limit on the spin-dependent WIMP (Weakly Interacting Massive Particles)-proton cross section by a direction-sensitive method. As a next step, we started an underground measurement in Kamioka Observatory located at 2700m w.e. underground. In this presentation I will report the result and the status of NEWAGE.

09:30  The DRIFT Directional WIMP Search Experiment (15'+5') (20') (files Slides pdf  ) Neil Spooner (University of Sheffield)

An update will be given of the latest progress on the DRIFT experiment at Boulby mine. Specifically we will address progress towards achieveing zero background and event by event discrimination at lowe threshold. (note: this is a place holder abstract - a final decision on the particular speaker will be made in a few weeks, assuming the talk is accepted)

08:30->09:50    Indirect searches - gammas, neutrinos, etc (Convener: Torsten Bringmann (SU Fysikum) ) (Location: FB42 )
08:30  WIMP halo around the Sun and prospects for gamma ray detection (15'+5') (20') (files Slides pdf  ) Sofia Sivertsson (Teoretisk Fysik, KTH)

If the dark matter consists of a WIMP of some sort, the non-zero cross section with ordinary matter will make the WIMPs cluster around heavy objects, such as the Sun, giving the Sun a WIMP halo. WIMP annihilations within this halo would give rise to gamma rays with very low background since the Sun does not produce photons with such high energies. We have made quite detailed Monte Carlo simulations of this overdensity of WIMPs around the Sun and calculated the gamma ray flux at earth from this halo. It is interesting to note that the density of WIMPs around the Sun does effectively not depend on the magnitude of the cross section with ordinary matter, which is often crucial in other searches for dark matter. Unfortunately, however, the calculated gamma ray flux at Earth from the WIMP halo around the Sun is found to be quite low.

08:50  Detecting Dark Matter annihilation lines with GLAST (15'+5') (20') (files Slides pdf  ) Tomi Ylinen (KTH/HIK)

Dark Matter constitutes one of the most intriguing but so far unresolved issues in astrophysics today. In many extensions of the Standard Model the existence of a stable Weakly Interacting Massive Particle (WIMP) is predicted. The WIMP is an excellent Dark Matter particle candidate and one of the most interesting scenarios include an annihilation of two WIMPs into two gamma-rays. If the WIMPs are assumed to be non-relativistic, the resulting photons will both have an energy equal to the mass of the WIMP and manifest themselves as a monochromatic spectral line in the energy spectrum. This type of signal would represent a "smoking gun" for Dark Matter, since no other known astrophysical process should be able to produce it. This talk will give an overview of the different approaches to a search for Dark Matter lines that the GLAST collaboration is pursuing and the various challenges involved.

09:10  Constraining Dark Matter hypothesis through observations of Dwarf Spheroidal galaxies with the GLAST-LAT detector. (15'+5') (20') (files Paper pdf;   files Slides pdf  ) Eric Nuss (LPTA - Montpellier University)

Measurement of gamma-rays from dark matter annihilations is perhaps one of the most challenging tasks for future gamma-ray observatories, such as the Gamma-Ray Large Area Space Telescope (GLAST). GLAST, launched on June 11 2008, is the next generation satellite for high-energy gamma-ray astronomy and the Large Area Telescope (LAT), GLAST main instrument, has excellent potential to either discover or to constrain a dark matter signal. Dwarf spheroidal galaxies, the largest clumps predicted by the cold dark matter scenario, are attractive targets for indirect search of dark matter because they are amongst the most extreme dark matter dominated environments. We present an overview of the GLAST Dark Matter and New Physics Working Group efforts in the study of the LAT capability to detect a gamma-ray flux coming from WIMP pair annihilations in Dwarf spheroidal galaxies.

09:30  Indirect search for DarkMatter from the Galactic Center (15'+5') (20') (files Slides pdf  ) Vincenzo Vitale (dip. Fisica & INFN Roma Tor Vergata)

High energy gamma ray observations can be used for the indirect search for annihilating Dark Matter. One of the possible observation strategy is the targeting of regions where high Dark Matter density is foreseen, such as the Galactic Center. This observation poses a challenge: to disentangle the possible Dark Matter signal from the bright gamma radiation of astrophysical sources. The Large Area Telescope on board of the GLAST satellite provides the best opportunity to date for such a study, because of its excellent sensitivity and angular resolution, as compared to the past satellite-borne detectors. A report of the GLAST LAT Dark Matter Group activities on this topic will be given.

Coffee break

10:10->10:50    Direct detection - experiments (Convener: Richard Gaitskell (Brown University) )
10:10  "DM-TPC: a novel approach to directional Dark Matter detection" (15'+5') (20') (files Slides pdf  ) Sciolla Gabriella (MIT)

Directional detection of dark matter can provide unambiguous observation of dark matter (DM) interactions even in the presence of insidious backgrounds. The DM-TPC collaboration is developing a detector with the goal of measuring the direction and sense ("head-tail") of nuclear recoils produced in spin-dependent DM interactions. The detector consists of a low pressure TPC with optical readout filled with CF4 gas at low pressure. A collision between a WIMP with a gas molecule results in a nucleus recoil of 1-2 mm. The measurement of the energy loss along the recoil allows us to determine the sense and the direction of the recoil. Results from a prototype detector operated in a low-energy neutron beam clearly demonstrate the suitability of this approach to measure directionality. In particular, the first observation of the "head-tail" effect for low-energy neutrons had been recently published by our Collaboration. A full-scale (1m^3) module is now being designed. This detector, which will be operated underground in 2009, will allow us to set limits on spin-dependent Dark Matter interactions using a directional detector. The sensitivity of this experiment will be discussed in this talk.

10:30  MIMAC: A large micro-tpc for directional non-baryonic dark matter search (15'+5') (20') (files Slides ppt  ) Daniel Santos (LPSC/IN2P3/CNRS/UJF/ENSPG)

A Micro-tpc MAtrix of Chambers of 3He and 19F is proposed as a directional detector for non-baryonic dark matter search. The purpose is to exploit the axial interaction of WIMPs with neutron (3He) and proton (19F) with a electron-recoil discrimination by the dual track-ionization detection. The complementary aspect of this axial detection with respect to the scalar one will be illustrated. In order to read-out the pixelized anode a dedicated electronics has been developped. The response of the first prototype of one of the micro-tpc chamber as well as the first measurement of ionization quenching factor in 4He at low energies (1 to 50 keV) will be presented.

10:10->10:50    Indirect searches - gammas, neutrinos, etc (Convener: Torsten Bringmann (SU Fysikum) ) (Location: FB42 )
10:10  WIMP neutrinos from the Sun and the Earth (15'+5') (20') (files Slides pdf  ) Mattias Blennow (Max-Planck-Institut für Physik)

We discuss the propagation treatment of the indirect dark matter detection using WIMP annihilations in the Sun and the Earth. In particular, we focus on treating neutrino interactions and oscillations in a consistent framework, including tau neutrino regeneration and a full three-flavor neutrino oscillation framework. We also discuss the equivalence of using a Monte Carlo approach - suited for inclusion in neutrino telescope Monte Carlos - and the density matrix formalism.

10:30  Cosmic Gamma-Ray Background Anisotropies and Dark Matter Annihilation (15'+5') (20') (files Slides ppt  ) Alessandro Cuoco (University of Aarhus (Denmark))

The extragalactic cosmic gamma-ray background (CGB) can provide signatures of Dark Matter Annihilation (DMA) not only through the imprint in the energy spectrum but also through the peculiar pattern and intensity of its anisotropies. These are expected to differ significantly with respect to a pure astrophysical origin of the CGB due to the peculiar quadratic dependence of the DMA signal from the DM density. I will discuss the DM signature expected in the power spectrum of the CGB anisotropies and the prospect for detection with the forthcoming GLAST observatory. The talk is based on arXiv:0710.4136 (to appear inPRD).

11:00->12:00    Dark matter cosmology / structure formation (Convener: Anne Green (University of Nottingham) )
11:00  Via Lactea II - A high-resolution view of galactic dark matter substructure (25'+5') (30') (files Slides pdf  ) Michael Kuhlen (Institute for Advanced Study)

It is a clear unique prediction of the cold dark matter paradigm of cosmological structure formation that galaxies form hierarchically and are embedded in massive, extended dark halos teeming with self-bound substructure or "subhalos". The amount and spatial distribution of subhalos around their host provide unique information and clues on the galaxy assembly process and the nature of the dark matter. I will present results from "Via Lactea II", the most recent in a series of high resolution numerical simulations of Galactic CDM substructure, with a particular focus on the possibility of GLAST detecting gamma-rays from DM annihilations in the centers of subhalos.

11:30  Lensing Constraints on Dark Matter Substructure in Galaxies (25'+5') (30') (files Slides pdf  ) Charles Keeton (Rutgers University)

The Cold Dark Matter paradigm predicts that galaxy dark matter halos contain hundreds of bound subhalos left over from the hierarchical galaxy formation process. The amount of substructure is sensitive to the nature of dark matter. Strong gravitational lensing provides the only probe of dark matter substructure in galaxies outside the Local Group. The positions, brightnesses, and time delays of the images in multiply-imaged quasars are all sensitive to dark matter subhalos over a wide range in mass. The theory of substructure lensing is rich and tractable, providing a firm foundation for observational studies. Existing data reveal the average amount of substructure, which is consistent with CDM predictions. Future large samples will allow us to measure the evolution of substructure with cosmic time, providing unique access to the distribution of dark matter on small scales, and key astrophysical evidence about the nature of dark matter.

Lunch break

13:00->15:10    Dark matter cosmology / structure formation (Convener: Carlos Frenk (Institute for Computational Cosmology, Durham University) )
13:00  Dynamics of the Milky Way Dwarf Satellites (25'+5') (30') (files Slides pdf  ) Louis Strigari (University of California, Irvine)

I will discuss recent progress in understanding the dark matter distributions of the Milky Way dwarf satellite population. I will focus on several topics, including: determination of the mass- to-light ratios of the least luminous known galaxies, using future proper motion measurements to constrain the central density of dwarf satellites, and using measurements of the dark matter distributions to predict annihilation signals from the faintest dwarfs. I will discuss implications that all of these results have for the formation of galaxies at the smallest mass scales and for the nature of dark matter.

13:30  Measurement of the dark matter velocity anisotropy profile in galaxy clusters (15'+5') (20') (files Slides pdf  ) Ole Host (Dark Cosmology Centre, NBI, Copenhagen)

The internal dynamics of a dark matter structure may have the remarkable property that the local temperature in the structure depends on direction. This is parametrized by the velocity anisotropy beta which must be zero for relaxed collisional structures, but has been shown to be non-zero in numerical simulations of dark matter structures. Here, we present a method to infer the radial profile of the velocity anisotropy of the dark matter halo in a galaxy cluster from X-ray observables of the intracluster gas. This non-parametric method is based on a universal relation between the dark matter temperature and the gas temperature which is confirmed through numerical simulations. We apply this method to observational data and we find that beta is significantly different from zero at intermediate radii. Thus we find a strong indication that dark matter is effectively collisionless on the dynamical time-scale of clusters, which implies an upper limit on the self-interaction cross-section per unit mass sigma/m~1cm^2/g. Extrapolating our analysis to radii smaller than what can be probed by numerical simulations at present, we find observational indications that $\beta$ increases to about 0.3.

13:50  Remnants of small-scale dark matter clumps (15'+5') (20') (files Slides pdf  ) Vyacheslav Dokuchaev (Institute for Nuclear Research of the Russian Academy of Sciences)

The small-scale dark matter clumps are efficiently disrupted at early stages of hierarchical structure formation and later in the Galaxy by tidal interactions with stars. It is demonstrated that a substantial fraction of clump remnants survive through the tidal destruction during the lifetime of the Galaxy if a clump core radius is rather small. The resulting mass spectrum of survived clumps is extended down to the core mass of a minimal mass clump. These survived dense remnants of tidally destructed clumps provide a suitable contribution to the amplification (boosting) of dark matter annihilation signal in the Galaxy.

14:10  A dark matter disk in the Milky Way (15'+5') (20') (files Slides  ) Justin Read (University of Zürich)

Predictions for the distribution of dark matter at the solar neighbourhood have so far modelled only the dark matter component. We show that the Milky Way stellar disc radically alters the expected phase space distribution of dark matter in the solar neighbourhood. Massive satellites that merge at redshift z~1 are preferentially dragged into the plane of the disc, depositing a thick disc of dark matter that is 0.25 – 1 times the density of the spheroidal dark matter halo. At the same time a thick disc of stars is deposited that matches that seen in our own Galaxy, but is less massive. The stellar thick disc is a real boon because it shares very similar kinematics to the dark disc, allowing us to infer quite accurately the rotational velocity and velocity dispersion of the dark disc at the solar neighbourhood (under the assumption that most of the thick disc was accreted). Although most likely less dense that the spheroidal dark matter, the dark disc is nonetheless important for calculating the expected flux of dark matter through the Earth because it co-rotates with the Earth with low rotation lag (~50km/s). We discuss the importance of the dark disc for future dark matter direct detection experiments and for estimating the capture rate of WIMPs in the Sun and Earth.

14:30  Signatures of the Milky Way's dark disk in current and future experiments (15'+5') (20') (files Poster pdf;   files Slides pdf  ) Tobias Bruch (University of Zurich, Physics Institute)

T. Bruch, J. I. Read, L.Baudis, G. Lake In $\Lambda$CDM, massive satellites are dragged into the disk-plane where they dissolve into a stellar thick disk. Recent simulations of galaxy formation revealed that the dark matter accompanied with the satellites should dissolve as well and form a more massive dark matter disk. The kinematics of the dark disk matches the stars that also entered in the satellites. The lower velocity with respect to Earth enhances the scattering rates in direct detection experiments at low recoil energy. Comparison of the rates at low and high recoil energy will improve constrains on the WIMP mass, in particular for masses $\gtrsim$ 100 GeV. The annual modulation signal from the dark disk is significantly boosted and the phase is shifted by $\sim$ 3 weeks with respect to the dark halo. The variation of the phase with recoil energy can be used to determine the WIMP mass once the dark disk properties are fixed by future astronomical surveys. Finally, the constraints from current direct detection experiments on the WIMP-nucleon scattering cross section improve by factors of 1.4 to 3.5 if the additional dark matter particle flux from the dark disk is included. In addition the lower velocity will also increase the capture rate of WIMPs in the Sun and Earth resulting in higher expected fluxes of annihilation products, like neutrinos which could be detected by current and future neutrino telescopes. In conclusion, there are several distinct features of the dark disk which allow the detection of the dark disk in current and future experiments.

14:50  Structure Formation in the Dark Component (15'+5') (20') (files Slides pdf  ) James Taylor (University of Waterloo)

Structure formation in the dark component of the universe is now a well- established branch of theoretical astrophysics, providing detailed models of the dark matter distribution on a wide range of scales. In the linear regime these models have largely been confirmed, by observations of gravitational lensing, galaxy clustering, and other tests. In the non-linear regime some uncertainties and controversies remain, both on the theoretical side and on the observational side. I will review the highlights of the theory and discuss the main points of controversy - the central slope of dark matter halos, the variation of halo properties with mass or other variables, the survival of substructure within halos, and the small-scale distribution of dark matter - with particular reference to direct and indirect detection experiments.

Coffee break

15:30->16:55    Indirect searches - charged cosmic rays (Convener: Dan Hooper (Fermilab/University of Chicago) )
15:30  PAMELA - an experiment searching for dark matter with cosmic antiparticles (35'+5') (40') Mirko Boezio (INFN Sezione di Trieste)

The PAMELA satellite experiment was launched into low earth orbit on June 15th 2006 for a 3 year mission. The combination of a permanent magnet silicon strip spectrometer, and a silicon- tungsten imaging calorimeter allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (~100 MeV - ~200 GeV) with high statistics. The primary scientific goal is the measurement of antiparticle energy spectra, allowing a search for exotic sources such as dark matter particle annihilations. The status of the PAMELA experiment will be reviewed with a particular focus on results concerning antiprotons and positrons.

16:10  Indirect dark matter search with the balloon-borne PEBS detector (15'+5') (20') (files Backup slides pdf;   files Slides pdf  ) Henning Gast (I. Physikalisches Institut B, RWTH Aachen)

A precision measurement of the cosmic-ray positron spectrum may help to solve the puzzle of the nature of dark matter. Pairwise annihilation of neutralinos, predicted by some supersymmetric extensions to the standard model of particle physics, may leave a distinct feature in the cosmic-ray positron spectrum. As the available data are limited both in terms of statistics and energy range, we are developing a balloon-borne detector (PEBS) with a large acceptance of 4000 cm^2 sr. A superconducting magnet creating a field of 0.8 T and a tracking device consisting of scintillating fibers of 250 um diameter with silicon photomultiplier readout will allow rigidity and charge determination to energies above 100 GeV. The dominant proton background is suppressed by the combination of an electromagnetic calorimeter and a transition radiation detector consisting of fleece layers interspersed with straw-tube proportional counters. The calorimeter uses a sandwich of tungsten and scintillating fibers that are again read out by silicon photomultipliers. The design study, based on a detailed Geant4 simulation and testbeam measurements, will be presented along with an interpretation of the currently available positron data in the context of the mSUGRA model. The constraints that future precise measurements could put on this model will be discussed.

16:30  Propagation of cosmic rays (20'+5') (25') (files Slides pdf  ) Aldo Morselli Morselli (NFN Roma Tor Vergata)

A large number of outstanding problems in physics and astrophysics are connected with studies of cosmic rays (CRs) and the associated diffuse emission (radio, microwave, X-rays, gamma rays) produced during their propagation. Among these problems are indirect searches for dark matter, the origin and propagation of CRs, particle acceleration in CR sources, such as SNRs, and the interstellar medium, studies of our local Galactic environment, CR propagation in the heliosphere as well as many others. New or improved instrumentation to explore these open issues is ready or under development. The high quality data collected by such experiments as INTEGRAL, EGRET, HESS, Magic, Milagro, Veritas, ACE, TIGER, BESS, PAMELA, CREAM, ATIC, TRACER, and to be collected by GLAST are becoming increasingly important for the understanding of the Universe that we live in. In this talk we will discuss recent developments in astrophysics of cosmic rays.

16:55->18:35    Multi messenger searches and the galactic centre (Convener: Douglas Finkbeiner (Harvard University) )
16:55  Multi-wavelength signals of dark matter annihilations at the Galactic center (15'+5') (20') (files Slides pdf  ) Marco Regis (S.I.S.S.A.)

I will present a study of the multi--wavelength signal induced by weakly interacting massive particle (WIMP) annihilations at the Galactic Center. Referring to a generic WIMP dark matter scenario and depending on astrophysical inputs, I will discuss spectral and angular features and sketch correlations among signals at different frequencies. Data-sets at all energy bands, namely the radio, near infrared, X-ray and gamma-ray bands, contribute to place significant constraints on the WIMP parameter space. The possibility of a dark matter discovery with the next generation of gamma-ray telescopes, like GLAST and CTA, and with wide-field radio observations, will be also briefly discussed.

17:15  Morphological and Spectral Features of the WMAP Haze (15'+5') (20') (files Slides pdf  ) Greg Dobler (Harvard University)

The WMAP "haze" is an extended region of excess microwaves towards the Galactic Center relative to known ISM emissions. I will first present the results of our analysis of the morphological and spectral features of the haze. From there, I will show that they are consistent with synchrotron emission from an injection of high energy electrons/positrons sourced by ~500 GeV neutralino DM annihilations with thermal relic cross section in the galactic DM halo with a rho~r^-1.2 density profile and no boost factor. Further, I will show that they are inconsistent with a point source injection from massive explosions such as GRBs, SNe, etc. Halo annihilations of this type have significant consequences for present and future indirect observations such as Planck, PAMELA, and GLAST.

17:35  Dark Matter Annihilations in the WMAP Sky (15'+5') (20') (files Slides ppt  ) Dan Hooper (Fermilab/University of Chicago)

The WMAP experiment has revealed an excess of microwave emission from the region around the center of our Galaxy. This signal, known as the "WMAP Haze'', has the properties expected of synchrotron emission from relativistic electrons and positrons generated in dark matter annihilations. In particular, the angular distribution of the WMAP Haze matches the prediction for dark matter annihilations with a cusped density profile, $\rho(r) \propto r^{-1.2}$ in the inner kiloparsecs. Comparing the intensity in different WMAP frequency bands, we find that a wide range of possible WIMP annihilation modes are consistent with the spectrum of the haze for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly, we find that to generate the observed intensity of the haze, the dark matter annihilation cross section is required to be approximately equal to the value needed for a thermal relic, $\sigma v \sim 3 \times 10^{-26}$ cm$^3$/s. No boost factors are required.

17:55  0-neutrino Double Beta decay, WIMPS, and High-Pressure Xenon Gas TPC (15'+5') (20') (files Slides pdf  ) David Nygren (SU Fysikum)
18:15  Coordinated multi-wavelength observations of the Dark Mass at the Center of the Milky Way (15'+5') (20') (files Slides pdf  ) Andreas Eckart (Universtity of Cologne, I. Physikalisches Institut)

The compact source SgrA* that can be associated with the massive black hole at the center of the Milky Way shows a strong variability from the radio to the X-ray wavelength domain. Here report on the latest (May 2008, May 2007 and the years before) simultaneous NIR/sub-millimeter/X-ray observations using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope, the Australian Telescope Compact Array, the US mm-array CARMA and other telescopes.We interpret the results using a model in which spots in an accretion disk are on relativistic orbits around SgrA*. We discuss the energy release from the X-rays to the radio domain in the framework of adiabatically expanding source components and consider the possibility of a jet or outflow from such a central accretion disk.

19:30->20:30    Public Lecture (in Swedish)
19:30  Universums historia på 45 minuter (45') (files Mer information om hur du hittar hit  ) Max Tegmark (MIT)

Jag bjuder på en resa genom tid och rum för att utforska vår kosmiska historia och framtid, svarta hål och andra sevärdheter. Efter att ha utforskat vårt galaktiska grannskap så reser vi 13.7 miljarder år bakåt i tiden för att utforska vår kosmiska urknall, Big Bang, och hur nya mätningar håller på att transformera vår förståelse av vårt kosmiska ursprung och framtidsöde. Om du har frågor om mörk materia, mörk energi, svarta hål, parallella universa eller annat kosmiskt så är det här ett utmärkt tillfälle att ställa dem.

Thursday 21 August 2008 toptop

09:00->10:00    Dark matter phenomenology / theory (Convener: Michael Gustafsson (Stockholm University) )
09:00  Dark Matter with Excited States (15'+5') (20') (files Slides pdf  ) Douglas Finkbeiner (Harvard University)

WIMPs with excited states (in the 100 keV to 1 MeV range) make possible a number of unconventional observational tests. There are already suggestions that such excited states (whether from internal structure in composite WIMPs, or near degeneracy induced by a weakly broken symmetry) explain previously observed phenomena, from the 511 keV line in the Galactic Center, (using a collisionally excited ~ 1MeV splitting) to the DAMA annual modulation (using 100 keV inelastic scattering to suppress the number of low-energy scattering events). In the case of eXciting Dark Matter (XDM; Finkbeiner & Weiner), we have recently realized that the natural lifetime of the excited state is 10^{13} - 10^{19} sec, causing the thermal relic excitation left over from the Big Bang to have possibly significant effects on the ionization and thermal history of the Universe, as measured by the high-z 21-cm line and the CMB. I will review the advantages and deficiencies of two leading models, and suggest a way forward.

09:20  Dynamics of WIMPs in the Solar System and Implications for Direct and Indirect Detection (15'+5') (20') (files Slides pdf  ) Annika Peter (California Institute of Technology)

Semi-analytic treatments of weakly interacting massive particle (WIMP) orbits in the solar system (e.g., Damour & Krauss 1999, Gould 1991, Lundberg & Edsjo 2004) suggest that the WIMPs bound to solar system may enhance the direct detection rate relative to that of the unbound population by up to a factor of order unity, as well as boost the flux of neutrinos from WIMP annihilation in the Earth up to two orders of magnitude. Given these intriguing implications, it is worthwhile to check the semi-analytic approximations with numerical integrations of particle orbits in the solar system. We present the results of a suite of numerical experiments to explore the size of the bound WIMP population as a function of WIMP mass and the elastic scattering cross section with baryonic matter. For regions of WIMP parameter space not yet excluded by experiments, we find that the bound WIMP population enhances the direct detection rate by at most $\approx 1\%$ relative to the halo WIMP rate. It is unlikely that neutrinos from WIMP annihilation in the Earth will be observed in upcoming km$^3$- scale neutrino telescopes. The event rate from neutrinos from WIMP annihilation in the Sun will depend on the WIMP mass and elastic cross section in ways that have not been previously explored.

09:40  DarkSUSY (15'+5') (20') (files Slides pdf  ) Joakim Edsjö (Stockholm University)

DarkSUSY is a tool for dark matter calculations mainly for supersymmetric models. The newly released version 5 will be described.

Coffee break

10:20->11:55    Neutrino properties (Convener: Tommy Ohlsson (Royal Institute of Technology (KTH)) )
10:20  Neutrino oscillation update (25'+5') (30') (files Slides pdf  ) Thomas Schwetz-Mangold (CERN)

An update on the global data on neutrino oscillations is given, including most recent results from solar, atmospheric, reactor, and long-baseline experiments, focusing on the three-flavour oscillation framework. I also comment on the status of various attempts to explain the LSND puzzle in the light of recent MiniBooNE results.

10:50  The GERDA Neutrinoless-Double-Beta decay experiment (15'+5') (20') (files Slides pdf  ) Bela Majorovits (Max-Planck-Institut für Physik)

Neutrinoless double-beta-decay could be the key to understanding the nature of the neutrino: If observed it would prove its Majorana-nature and the half-life of the decay would be a direct measure of the yet unknown absolute scale of the neutrino mass. The GErmanium Detector Array (GERDA) is designed to search for neutrinoless double-beta-decay of the isotope 76Ge. Germanium crystals enriched in 76Ge, acting as source and detector simultaneaously, will be submerged directly into their ultra pure cooling medium that also serves as a radiation shield. This concept will allow for a background reduction of up to two orders of magnitudes with respect to earlier experiments, i.e. to a level of 10^{-3} counts/kg/y/keV at the Q value of 2039 keV. GERDA is being installed in the Hall A of the Gran Sasso underground Laboratory (LNGS), Italy. The design, status and reach of the experiment will be discussed.

11:10  From Cuoricino to CUORE: approaching the inverted hierarchy region (15'+5') (20') (files Slides ppt  ) Andrea Giuliani (University of Insubria and INFN)

CUORICINO is a Double Beta Decay (DBD) experiment operating deep underground, at the Gran Sasso National Laboratory (Italy) at a depth of about 3500 m.w.e. The search for the 0vDBD of 130Te is carried out with the bolometric technique. The experiment consists of an array of 62 TeO2 crystal bolometers arranged in a 13-planes tower structure, operating at a temperature of about 10 mK. The total mass of the detectors is of 40.7 kg, corresponding to about 11 kg of 130Te. The background in the 0vDBD region, expected at 2530 keV, is 0.18+- 0.01 c/keV/kg/y. No peak appears at the Q-value of the decay and with a Maximum Likelihood procedure an upper limit of 2.4x10^24 y (90%C.L.) is set for the 0nDBD of 130Te. CUORICINO represent not only the largest DBD Experiment presently operating but also a prototype for the next generation experiment, CUORE. CUORE will be a tightly packed array of 988 TeO2 bolometers arranged in 19 vertical towers with a semi cylindrical structure placed in a special dilution refrigerator. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of the present CUORICINO results indicate that CUORE will be able to test the 0.02-0.05 eV region for the effective neutrino mass, having a great potential discovery in the inverted hierarchy region.

11:30  The Karlsruhe Tritium Neutrino experiment KATRIN (20'+5') (25') (files Slides pdf  ) Christian Weinheimer (University of Münster, Germany)

The relic neutrinos are the hot component of dark matter. Their contribution to the energy/matter content to the universe and, hence, their importance for cosmology scales directly with the yet unknown absolute scale of the neutrino mass. Our information on the neutrino mass scale comes from three complementary methods: a) cosmological observations and modelling and from laboratory experiments searching for b) neutrinoless double beta decay and c) directly for the neutrino mass by precisely determining the shape of a beta spectrum near its endpoint. The KArlsruher TRItium Neutrino experiment KATRIN is going to search for the neutrino mass from tritium beta decay with one order of magnitude higher sensitivity of 0.2 eV/c2 compared to previous direct neutrino mass experiments. This sensitvity will allow to distinguish between hierarchical and quasi-degenerate neutrino mass scenarios as well as to investigate the whole cosmological relevant neutrino mass range. The KATRIN experiment is currently being set up at Forschungszentrum Karlsruhe/Germany by an international collaboration. The key elements of KATRIN are a windowless gaseous molecular tritium source with very high luminosity, which minimizes systematic uncertainties, a very effective tritium retention and electron guiding system, the 23m long and 10m diamter main spectrometer of MAC-E-Filter type, and an electron detector. This setup allows to measure the tritium beta spectrum with unprecedented signal rate and energy resolution of 0.93eV. The scientific context, the present status of KATRIN, its technical challenges and a discussion on KATRIN`s systematics and sensitivity will be presented.

Lunch break

13:00->14:40    Dark Stars (Convener: Aldo Morselli Morselli (NFN Roma Tor Vergata) ) (Location: FB53 )
13:00  Impacts of WIMP dark matter upon stellar evolution: main-sequence stars (15'+5') (20') (files Slides pdf  ) Pat Scott (Dept. Physics, Stockholm University)

The presence of large amounts of WIMP dark matter in stellar cores has been shown to have significant effects upon models of stellar evolution. We present a series of detailed grids of WIMP-influenced stellar models for main sequence stars, computed using DarkStars. We describe the changes in stellar structure and main sequence evolution which occur for masses ranging from 0.3 to 2.0 solar masses and metallicities from Z = 0.0003 to 0.02, as a function of the rate of energy injection by WIMPs. We then go on to show what rates of energy injection can be obtained using realistic orbital parameters for stars near supermassive black holes, including detailed considerations of dark matter halo velocity and density profiles. Capture and annihilation rates are strongly boosted when stars follow elliptical rather than circular orbits, leading to punctuated evolution.

13:20  Dark Stars: a new phase of stellar evolution in the first stars due to DM annihilation (15'+5') (20') (files Slides pdf  ) Paolo Gondolo (University of Utah)

Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the the universe. Hence these first stars may experience a new phase of stellar evolution: they may be powered by dark matter annihilation for an extended period of time en route to become fusion driven stars. This talk presents an examination of the stellar structure of the Dark Stars and discusses possibilities for their detection.

13:40  Dark Stars (15'+5') (20') (files Slides pdf  ) Douglas Spolyar (UC Santa Cruz)
14:00  Dark Matter annihilations and the First Stars (15'+5') (20') (files Slides pdf  ) Emanuele Ripamonti (Universita' dell'Insubria)

We study the effects of WIMP dark matter (DM) annihilations on the collapse and evolution of the first stars in the Universe. First, we use a 1-D hydrodynamical code to study the final phases of the protostellar collapse, exploring the parameter space in order to determine whether the energy input from annihilations can modify the star formation process. Then, we use a stellar evolution code to follow the pre-Main Sequence (MS) phase of a grid of metal-free stars, looking for the effects of the DM energy input on their evolutionary tracks. In our calculations we account for adiabatic contraction and scattering/capture processes. Such processes can enhance the central DM density so much that the annihilations can effectively counteract the gravitational collapse: in some instances the protostar is prevented from reaching the ZAMS, while in other cases the changes (e.g., a doubling of the MS life) are less dramatic.

14:20  WIMPs annihilations in PopIII stars (15'+5') (20') (files Slides pdf  ) Marco Taoso (University of Padova & Institut d'Astrophysique de Paris)

We have studied the impact of WIMPS annihilations on the evolution of pop III massive stars in Dark Matter halos. The evolution during the core H-burning phase and core He-burning phase has been followed for stars of 20 and 200 M_{\odot} and for different Halo Dark Matter densities. We have found that for the 20 M_{\odot} star, below a WIMP density of about 4 10^9 GeV cm−3, the core H-burning phase is increased by less than 10%. Beyond a WIMP density of about 7 10^9 GeV cm−3, the H-burning lifetime increases rapidly when higher values of DM densities are taken into account and, when the DM density approaches 2.5 10^9 GeV cm−3, the core H-burning lifetime becomes equal to the Hubble time. For higher densities, the DM luminosity inhibits the evolution of the stars that remains indefinetely frozen. These Pop III stars present anomalous mass-radius relation that would unambiguously distinguish them from normal stars.

13:00->14:40    Background studies and detector ideas for direct detection (joint with ILIAS meeting) (Convener: Vitaly Kudryavtsev (University of Sheffield) ) (Location: FB52 )
13:00  ILIAS and the Underground Laboratories of Europe (15'+5') (20') (files Slides pdf  ) Neil Spooner (University of Sheffield)

An overview will be given of the status and prospects for the deep underground laboratories of Europe from the perspective of the ILIAS (Integrated Large Infrastructures for Astroparticle Science) consortium.

13:20  What do we need to know about background to design high-sensitivity direct dark matter experiments? (15'+5') (20') (files Slides pdf  ) Vitaly Kudryavtsev (University of Sheffield)

The status of background studies for direct WIMP dark matter searches will be reviewed. Major sources of background, such as radioactivity and cosmic rays, will be considered. Special emphasis will be given to high-energy neutrons able to mimic the expected signal from WIMPs. Requirements for material purity, shielding, active veto systems etc. will be summarised. Projected sensitivity of future large-scale experiments will be discussed.

13:40  Limits on Low-Mass WIMP Dark Matter with an Ultra-Low-Energy Germanium Detector at 220 eV Threshold (10'+5') (15') (files Slides pdf  ) Henry Wong (Academia Sinica)

An energy threshold of (220+-10) eV was achieved at an efficiency of 50% with a four-channel ultra-low-energy germanium detector [1] each with an active mass of 5 g. This provides a unique probe to WIMP dark matter with mass below 10 GeV. With low background data taken at the Kuo-Sheng Laboratory, constraints on WIMPs in the galactic halo were derived. Both the spin- independent and the spin-dependent bounds improve over previous results on the WIMP couplings with the nucleons for WIMP mass between 2-6 GeV [2]. Sensitivities for full-scale experiments were projected. This detector technique makes the unexplored sub-keV energy window accessible for new neutrino and dark matter experiments [1]. References: 1. H.T. Wong, arXiv: hep-ex/0803.0033 (2008). 2. S.T. Lin et al., arXiv: hep-ex/0712.1645 (2007) .

13:55  Identification of the Beta Background in the CDMS II Experiment (10'+5') (15') (files Slides pdf  ) Sunil Golwala (California Institute of Technology)

The primary background of concern for the Cryogenic Dark Matter Search (CDMS II) and SuperCDMS experiments is beta emission from radioactive contaminants at the detector surfaces. Because of an ionization dead layer, the likelihood of misidentifying the interactions of low-energy electrons as WIMP scatters is substantially higher than for photon interactions. We report an analysis that successfully identifies the primary source of the beta background on CDMS II detectors as 210Pb. The analysis makes use of correlations between beta rates due to 210Pb decay with alpha rates due to 210Po decay. A global fit is done to obtain the 210Pb contamination present on all detectors. The analysis relies critically on the fact that the CDMS II detectors face each other with no intervening material, providing a large number of double-scatter events that uniquely identify the 210Pb chain. We also analyze whether the 210Pb contamination lies on the detector surfaces or is implanted into them and whether the contamination levels correlate well with radon exposure records. Sensitivity implications for the final CDMS II data set and for the SuperCDMS experiment are presented.

14:10  The LVD core facility: a study of LVD as muon veto and active shielding for dark matter experiments (10'+5') (15') (files Slides ppt  ) Marco Selvi (INFN - Bologna)

Many experiments looking for dark matter are aiming to get the ton scale in the future. However, it is well known that scaling dark matter detectors to higher mass is not a sufficient condition for sensitivity and that an equally important condition is to simultaneously keep the background low, in particular the ultimate background, namely the fast neutron background induced by muons. In this presentation we study the possibility of using the existing structure of a running experiment, the LVD supernova observatory at the INFN Gran Sasso National Laboratory, as an active shield and veto for the muon-induced background. In our vision LVD could become (without affecting in any way its main purpose of SN neutrino telescope) a ‘host’ for a relatively compact but massive experiment looking for rare events. The LVD experiment consists of a 1000 ton liquid scintillator detector with a highly modular structure, being made of 3 identical towers, each one composed by 35 active modules. The empty volume that can be obtained removing 2 modules from the most internal part of the detector is 2.1m x 6.2m x 2.8m; we will call it “LVD core facility” (LVD-CF). We have evaluated the active vetoing and shielding power of LVD, with a detailed MC simulation (based on Geant4) of the detector and the rock that surrounds it. We have generated cosmic muons with energy spectrum and angular distribution sampled accordingly to what is expected in the LNGS underground laboratory (=270 GeV). The number and energy spectrum of the muon-induced neutrons that enter the LVD-CF has been calculated. The results show that the flux of neutrons that are not associated with a visible muon in LVD is very low; it results equivalent to the one present in a much deeper underground laboratory, i.e. Sudbury. Moreover we will present the results of on-going measurements about the gamma contamination inside the LVD-CF: the gamma ray intensity inside the LVD-CF is reduced by a factor greater than 10 with respect to the one measured outside the LVD detector.

14:25  BACKGROUND LEVEL ESTIMATIONS USING PULSE SHAPE ANALYSIS IN Ge EXPERIMENTS (10'+5') (15') (files Slides ppt  ) Hector Gomez Maluenda (Universidad de Zaragoza)

Some neutrino properties, like its mass, could be determined or at least delimited using germanium detectors enriched in 76Ge and studying the neutrinoless double beta decay of this isotope. Furthermore this kind of detectors can also be used for detection of Dark Matter exploring the low energy region. In order to have the sensitivity required, the background level should be around 0.001 c/keV/kg/y in the region of interest for the neutrinoless double beta decay sigal. Some previous studies show that rejection of background events using Pulse Shape Analysis can be a very powerful tool to reach this level (H. Gómez et al. Astrop. Phys. 28 (2007) 435-447) offering high efficiency for neutrinoless double beta decay events detection. To determine the rejection capability of this method and the detection efficiency, a set of simulations were developed showing that three-dimensional spatial resolution and not only in radial direction, is necessary in order to reject enough background multi-site events to reach the required level.

Coffee break

15:00->16:40    Theoretical models and related topics (Convener: Yudi Santoso (IPPP, University of Durham, UK) ) (Location: FB53 )
15:00  Inverse See--saw Neutrino Masses and Sneutrino Dark Matter (15'+5') (20') (files Slides pdf  ) Federica Bazzocchi (Universidad de Valencia- IFIC)

The generation of neutrino masses and the determination of a suitable particle dark matter candidate are twoevidences which point towards the existence of new physics beyond the Standard Model. The two problems may arise from a single sector of an extended theory: in a mSUGRA scheme with the addition of singlet superfields, the neutrino mass and its lightness are naturally obtained with the mechanism of inverse seesaw and the dark matter is represented by the corresponding neutrino superpartner, the sneutrino. Such a model successfully accommodates light neutrino masses and sneutrinos dark matter with correct relic abundance and direct detection rates.

15:20  Artifact Dark Matter from Unified Brane Gravity (15'+5') (20') (files Slides pdf  ) Ilya Gurwich (Ben-Gurion University)

Adopting Dirac's brane variation prescription, the energy-momentum tensor of a brane gets supplemented by a geometrical (embedding originated) dark component. While the masslessness of the graviton is preserved, and the Newton force law is recovered, the corresponding Newton constant is necessarily lower than the one which governs FRW cosmology. This has the potential to puzzle out cosmological dark matter (a subsequent conjecture concerning galactic dark matter follows). Unified brane cosmology, on the other hand, gives rise to a novel scalar field free radiation driven inflation, such that the inflationary and the radiation dominated eras are nothing but two different phases (phase transition as the exit mechanism) governed by one and the same energy density.

15:40  General Relativistic Rotation Curves in a Post-Newtonian Light (15'+5') (20') (files Slides pdf  ) Aleksandar Rakic (Würzburg University)

The missing of a Keplerian fall-off in the observed galaxy rotation curves represents the main classical evidence for the existence of dark matter on galactic scales. In a recent (2005-2007) series of works Cooperstock and Tieu argued that a general relativistic treatment of a galactic system may introduce effects that are qualitatively completely new in defiance of the fact that the involved velocities and fields are small because of the advent of non-linearities peculiar to general relativity. Cooperstock and Tieu proposed a concrete general relativistic model of a galactic system that both recovers a realistic density profile of the galaxy and is able to produce a flat rotation curve. However, the Cooperstock and Tieu model has been argued to be unphysical by a number authors, mainly stressing the existence of exotic matter in the z=0 plane. Nevertheless, the idea of a general relativistic galaxy model appears interesting, especially because of the striking lack of physically acceptable and working such models in the literature. Here we want to dissect the Cooperstock and Tieu model in terms of a (Post)- Newtonian reasoning. By applying the full maschinery of the Arnowitt-Deser-Misner split we illustrate the differences of a rotating, axially symmetric Post-Newtonian model to the proposed Cooperstock and Tieu solution. We aim at identifying the new physics coming in from the Cooperstock-Tieu model in the framework of a fully Post- Newtonian treatment with special emphasis on the galactic rotation curve.

16:00  Dark matter candidates from strong coupled theories (15'+5') (20') (files Slides pdf  ) chris kouvaris (Niels Bohr Institute)

New technicolor theories can provide a natural way of breaking the electroweak symmetry, without violating the precision measurements. In addition, they can provide several interesting dark matter candidates. These candidates can be WIMP and/or SIMP type. In particular one of them has similar properties to the neutralino, making technicolor an attractive alternative to supersymmetry.

16:20  Minimal Dark Matter (15'+5') (20') (files Slides pdf  ) Marco CIRELLI (CNRS & IPhT Saclay)

The Dark Matter problem calls for new physics, likely in the form of a cosmologically stable, electrically neutral, weakly interacting particle with a mass around the TeV scale. Many 'beyond the Standard Model' constructions (most notably SuperSymmetry) provide plausible candidates as a by-product of more ambitious goals, but these often have a complicated phenomenology (due to the large number of unknown parameters) and an ad hoc mechanism is responsible for their stability on cosmological scales (e.g. R-parity in SuSy). We explore therefore a more minimalistic approach: on top of the Standard Model, we only introduce fermionic or scalar multiplets with SM gauge interactions and we look for good DM candidates. We find indeed some fully successful candidates. Remarkably, for some of them the stability is automatically guaranteed by renormalizability, like proton stability. For these candidates, we compute precisely the mass, the cross section for direct detection in future experiments, the indirect detection signatures and the other distinctive phenomenology features.

15:00->17:00    Background studies and detector ideas for direct detection (joint with ILIAS meeting) (Convener: Vitaly Kudryavtsev (University of Sheffield) ) (Location: FB52 )
15:00  Calculation of backrounds from radioactivity in dark matter detectors (10'+5') (15') (files Slides pdf  ) Vito Tomasello (University of Sheffield & Universität Tübingen)

New generation dark matter experiments aim at exploring the 10e-9 - 10e-10 pb cross-section region for the WIMP-nucleon scalar interactions. Neutrons and gamma-rays produced in detector components are the main factors that can limit detector sensitivity. Energy spectra and production rates of neutrons coming from radioactive contamination of materials with uranium and thorium have been estimated using the code SOURCES4A. The code libraries for (alpha,n) cross-section and transition probabilities have been updated and extended using the code EMPIRE 2.19. Radioactive background event rates from some detector components (such as copper and stainless steel), as well as from rock and concrete (lab walls), have been estimated for a hypothetical dark matter detector based on Ge crystals (for instance EURECA). Different shielding configurations (water, lead, paraffin) have been considered. Neutrons and photons have been propagated to the detector using GEANT4. Some requirements for the radiopurity of the materials have been deduced from the results of these simulations. Thickness of shielding in different configurations and required gamma discrimination factor have been investigated.

15:15  Measurements and simulations of neutrons produced by high-energy muons (10'+5') (15') (files Slides pdf  ) Vitaly Kudryavtsev (University of Sheffield)

We present the first measurements of the muon-induced neutron flux at the Boulby Underground Laboratory. The experiment was carried out with an 0.73 tonne liquid scintillator that also served as an anticoincidence system for the ZEPLIN-II direct dark matter search. The experimental method exploited the delayed coincidences between high-energy muon signals and gamma-rays from radiative neutron capture on hydrogen or other elements. The muon-induced neutron rate, defined as the average number of detected neutrons per detected muon, was measured as $0.079 \pm 0.003$ (stat.) neutrons/muon using neutron-capture signals above 0.55 MeV in a time window of 40-190 $\mu$s after the muon trigger. Accurate Monte Carlo simulations of the neutron production, transport and detection in a precisely modeled laboratory and experimental setup using the GEANT4 toolkit gave a result 1.8 times higher than the measured value. The difference greatly exceeds all statistical and systematic uncertainties. As the vast majority of neutrons detected in the current setup were produced in lead we evaluated from our measurements the neutron yield in lead as $(1.31 \pm 0.06) \times 10^{-3}$ neutrons/muon/(g/cm$^2$) for a mean muon energy of about 260 GeV.

15:30  Studies of the muon-induced neutron background in LSM: detector concept and status of the installation (10'+5') (15') (files Slides ppt  ) Valentin Kozlov (KIT (FZK))

Motivated mainly by astrophysical observations, the idea of the existence of Dark Matter has strong support today while its nature and origin remains one of the big science quests. A good particle candidate for Cold Dark Matter (CDM) is the supersymmetric neutralino or more generally a weakly interacting massive particle (WIMP). The expected interaction rate of WIMPs with the detector medium in the direct detection experiments is below 0.01 events / (kg day). This makes a good knowledge of the background conditions highly important, especially with ever increasing sensitivity of the detectors. One of the background components is related to cosmic muons and in particular to muon- induced neutrons. Detailed studies carried out by the Edelweiss collaboration in this respect will be presented. This activity includes GEANT4 simulations with full event topology as well as a dedicated measurement with a new neutron counter based on 1 tonne of liquid scintillator to be installed in fall 2008 in LSM (Modane, France). This counter will be incorporated into the existing muon veto system thus allowing to monitor neutrons in coincidence with the incoming muons. This work is in part supported by the German Research Foundation (DFG) through the Transregional Collaborative Research Center SFB-TR27 as well as by the EU contract RII3-CT-2004-506222.

15:45  Surface radioactivity, a common problem in bolometric Dark Matter and Double Beta Decay searches: a joint solution. (10'+5') (15') (files Slides ppt  ) Claudia Nones (Universita' dell'Insubria & INFN Milano-Bicocca)

The present limitation for experiments looking for rare events, such as direct WIMPs detection and neutrinoless double beta decay, is the radioactive background. In particular, near-surface events are the main problem; in fact for a 0vBB experiment they cause signals close to the Q-value while for a dark matter experiment, which exploits ionization signal for particle identification, they originate an incomplete charge collection simulating a nuclear recoil. After very promising results obtained on germanium and sapphire bolometers, here we present some results on small TeO2 crystals equipped with one or two NbSi films. TeO2 is an interesting material for the search for 0vBB of Te-130. NbSi films are used as Anderson insulator thermometric layers and they are evaporated directly on the TeO2 absorber. The main characteristic of this films is that they are sensitive to athermal phonons. A particle interaction in the TeO2 absorber will produce out-of- equilibrium phonons diffusing away from the impact zone. In the case of a near surface event, a large amount of these high energy phonons will be trapped by the NbSi film and induce an athermal heat signal much larger than the one created by a bulk event of the same energy. Pulse shape analysis clearly suggests a rejection procedure. We present first attempts to identify alpha surface events on TeO2 by this pulse shape analysis using different experimental configurations, both in above- and under-ground tests. Bulk and surface events are well separated. We will also discuss other possible uses of metal films on crystal surfaces to tag surface events.

16:00  Discussion (45')
Conference dinner and boat excursion

Friday 22 August 2008 toptop

09:00->10:05    Indirect searches - neutrinos (Convener: Mirko Boezio (INFN Sezione di Trieste) )
09:00  Indirect Dark Matter search with the ANTARES neutrino Telescope (15'+5') (20') (files Slides pdf  ) Jean-Pierre Ernenwein (Université de Haute Alsace)

The ANTARES neutrino telescope was completed in June 2008, comprising 12 lines of photomultipliers immersed in the Mediterranean Sea at a depth of 2500 m, located 40 km from the French coast. The ANTARES experiment is based on Cerenkov light detection: the neutrino interaction, inside the large volume of matter surrounding the detector, produces charged particles, which leads to Cerenkov light emission in the water. A 5-line ANTARES was operational for 10 months during 2007. In December 2007, the telescope grew to 10 lines and the full detector (12 lines) has been operational since June 2008. ANTARES is intended to detect neutrinos, both astrophysical and those originating from self-annihilation of Dark-Matter particles. Within the framework of Supersymmetry the lightest supersymmetric particle, the neutralino, is stable assuming R-parity conservation; in this regime it provides a compelling candidate for the Dark-Matter. In addition, the constrained gravity mediated Supersymmetry (mSugra) scenario allows estimates to be made of the expected rates of neutrinos resulting from neutralino annihilation. At present, the Sun is regarded as the best neutralino-induced neutrino source as it is an efficient and nearby gravitational trap for WIMPs. I will present the expected sensitivity of ANTARES in this context.

09:20  KM3NET (km3-scale neutrino telescope)- potential for indirect dark matter detection (15'+5') (20') (files Slides pdf  ) paschal coyle (Centre de Physique des Particules de Marseille)

KM3NET is a future deep-sea research infrastructure located in the Mediterranean Sea. It will include a km3-scale neutrino telescope, optimized for the search of high-energy neutrinos produced by astrophysical neutrino sources and/or via self-annihilation of Dark-Matter particles. The detection principle relies on the observation of Cerenkov light emitted by muons resulting from charged current neutrino interactions in the sea water or sea floor surrounding the detector. Based on, minimal Supergravity (mSugra) and Kaluza-Klein models, predictions for the fluxes of high-energy neutrino flux originating from dark matter annihilation in the Sun, are presented. The expected sensitivity of KM3NET to dark matter is discussed.

09:40  Search for Dark Matter with the AMANDA and IceCube neutrino detectors (20'+5') (25') (files Slides pdf  ) Catherine De Clercq (Vrije Universiteit Brussel)

If non-baryonic dark matter exists in the form of neutralinos, a neutrino flux is expected from the decay of neutralino pair annihilation products inside heavy celestial bodies. Data taken with the AMANDA neutrino telescope located at the South Pole has been used in a search for this indirect dark matter signal. Results will be shown from searches for neutralinos accumulated in the Sun and in the centre of the Earth, using the data taken up to 2003. The IceCube neutrino detector is being deployed at the South Pole since 2006. This cubic kilometer observatory with 80 strings of 60 photomultipliers will be completed in 2011. The data taken in 2007 with 22 strings has been searched for a neutrino signal from neutralinos in the Sun. Preliminary results of this analysis will be shown. The planned IceCube detector will be complemented with a dense inner core, DeepCore, to improve the sensitivity in the GeV-TeV energy domain. In the talk we will discuss the expected performance of the combined IceCube-DeepCore detector in relation to dark matter searches.

Coffee break

10:25->11:45    Dark matter cosmology / structure formation (Convener: Louis Strigari (University of California, Irvine/Stanford/KIPAC) )
10:25  Final results from EROS Microlensing search for Massive Compact Halo Objects (15'+5') (20') (files Slides ppt  ) marc moniez (IN2P3-CNRS)

EROS has monitored 70 million of stars towards the LMC, the SMC and the galactic plane during 7 years, to search for microlensing effects due to Milky-Way halo and disk objects. The final analysis of this complete set of data will be presented. We will show that stellar and sub-stellar mass compact objects do not significantly contribute to the galactic halo mass and also that there is no signal from a thick disk made of compact objects.

10:45  Red halos and dark baryons (15'+5') (20') (files Slides pdf  ) Erik Zackrisson (Tuorla Observatory, Finland)

On cosmological scales, somewhere between half and one third of the baryons in the low-redshift Universe are still unaccounted for, and the fraction of baryons missing from within the virial radii of galaxy-sized dark matter halos is of the same order. While the baryonic fraction of the overall dark matter is subdominant on large scales, the dark baryons may have a spatial distribution that is substantially different from that of the CDM and may therefore potentially interfere with attempts to test the clustering properties of CDM on subgalactic scales. Current models suggest that most of the dark baryons should be in the form of hot, tenuous gas, but a number of observations challenge this view, indicating that some of the missing baryons may be hiding in a cold, collapsed form. The red halos of galaxies represent one such piece that doesn't quite fit the puzzle. Over the last 15 years, deep optical/near-IR images of galaxies have revealed faint and very red structures around galaxies of different types. The colours of these halos are too extreme to be reconciled with any type of previously detected stellar population, and non-stellar explanations like dust or ionized gas are also disfavoured. A stellar population containing an abnormally high fraction of low-mass stars is on the other hand consistent with all available data. Because of its high mass-to-light ratio, such a halo population could contribute substantially to the baryon budget of galaxies, despite adding as little as one percent to their overall light. Here, we review the current status of this field and report on ongoing searches for red halos around types of galaxies for which similar structures have not yet been detected. We also address the constraints that direct star counts in the halo of the Milky Way impose on any putative red halo of low-mass stars around our own galaxy, and discuss the implications for red halos around disk galaxies in general.

11:05  Detecting CDM substructure via gravitational millilensing (15'+5') (20') (files Slides pdf  ) Teresa Riehm (Stockholm University)

In the cold dark matter (CDM) scenario, dark matter halos are assembled hierarchically from smaller sub units. A long-standing problem with this picture is that the number of subhalos predicted by CDM simulations is orders of magnitudes higher than the known number of satellite galaxies in the vicinity of the Milky Way. A possible way out of this dilemma could be that the majority of these subhalos somehow must have evaded detection. One promising possibility for detecting such "dark galaxies" is to try to observe their gravitational lensing effects on background sources. Dark matter subhalos in the 1e6 - 1e10 solar mass range should cause strong gravitational lensing on (sub)milliarcsecond scales. We study the feasibility of a strong-lensing detection of dark subhalos by deriving the image separations expected for density profiles favoured by current simulations and comparing it to the angular resolution of both existing and upcoming observational facilities. We find that there is a reasonable probability to observe subhalo lensing effects and thereby unravel the mystery of the existence of dark galaxies.

11:25  The search for dark matter via strong lens inversions of galaxy clusters using genetic algorithms (15'+5') (20') (files Slides pdf  ) Jori Liesenborgs (Hasselt University)

Gravitational lensing provides a direct means for measuring the masses of galaxies and galaxy clusters. Provided that enough constraints are available, one might even hope to obtain a handle on the precise distribution of the mass, which in turn may reveal information about the spatial distribution of the dark matter. We present an approach using genetic algorithms, allowing the user to 'breed' solutions which are compatible with available strong lensing data. The procedure allows various types of constraints to be used, including positional information, null-space information, and time-delay measurements. The method is non- parametric in the sense that it does not assume a particular shape of the mass distribution. This is accomplished by placing circularly symmetric basis functions -- projected Plummer spheres -- on a dynamic grid in the lens plane. Using simulations, we show that our procedure is able construct a mass distribution and source positions that are compatible with a given set of observations. We discuss the degeneracies that are inherent to lens inversion (and hence any lens inversion technique) and that limit the potential of strong lensing to yield precise estimates of the dark-matter distribution. We show how these degeneracies cause of the differences between inversions of the same lensing cluster by different authors, using the famous cluster Cl 0024+1654 as a working example.

11:45->12:00    Conference Photo (Convener: Joakim Edsjö (Fysikum) ) (Location: Main staircase in main buidling )
11:45  Conference Photo (15')
Lunch break

13:00->14:40    Axions - theory and experiment (Convener: Biljana Lakic (Rudjer Boskovic Institute) )
13:00  Dark matter related to axion and axino (40'+5') (45') (files Slides ppt  ) Jihn Kim
13:45  First Results from the Axion Dark Matter eXperiment (ADMX) Upgrade (25'+5') (30') (files Slides pdf  ) Karl van Bibber (Lawrence Livermore National Laboratory)

The axion, a hypothetical elementary pseudoscalar arising from the Peccei- Quinn solution to the strong-CP problem, is a well-motivated candidate to constitute the dark matter of the universe. Presently the axion mass is constrained to the range of a micro- to a milli-eV, with lower masses favored if the axion is cosmologically significant. As proposed by Sikivie in 1983, the axion’s two-photon coupling lends itself to a feasible search strategy with currently available technology. In this scheme, axions resonantly convert to single microwave photons by a Primakoff interaction, in a tunable microwave cavity permeated by a strong magnetic field. In its first phase (1995-2003), the Axion Dark Matter eXperiment (ADMX) utilized Heterojunction FET amplifiers, with a total system noise temperature of ~3 K, to detect the conversion signal, expected to be ~ 10^{–(22-23)} W. Axionic dark matter has been excluded well into the band of realistic model couplings, for nearly an octave of mass range, 1.9 – 3.4 μeV. The experiment was recently upgraded to dc SQUID amplifiers, which ultimately promise to reduce the system noise temperature to ~100 mK. Published data from the first phase, and preliminary data from the upgraded experiment will be presented.

14:15  Constraints on chameleons and axions-like particles from the GammeV experiment (20'+5') (25') (files Slides pdf  ) Jason H. Steffen (Fermilab Center for Particle Astrophysics)

We present the most recent results of both aspects of the GammeV experiment. The first aspect is a search for axion-like particles using a variable baseline, "light-shining-through-a-wall" technique. This search excludes the particle interpretation of the PVLAS signal with high confidence. The second aspect of the GammeV experiment is a search for chameleon particles, scalar particles which may be responsible for the dark energy of the universe. This is accomplished by looking for a characteristic afterglow signature from a "particle-in-a-jar" experiment whereby chameleon particles become trapped in a region with a high magnetic field and slowly decay into detectable photons. This is the first use of this experimental technique to probe for these particles. We place interesting limits on general chameleon models and, in particular, on cosmologically relevant chameleon models. These limits are complimentary to other experiments, such as torsion pendulum experiments, which probe for forces that would result from new scalar particles.

Coffee break

15:00->15:50    Axions - theory and experiment (Convener: Karl van Bibber (Lawrence Livermore National Laboratory) )
15:00  Search for solar axions with the CAST experiment (20'+5') (25') (files Slides pdf  ) Biljana Lakic (Rudjer Boskovic Institute, Zagreb, Croatia)

The CERN Axion Solar Telescope (CAST) is searching for axions produced by the Primakoff process in the solar core. CAST is using a Large Hadron Collider (LHC) test magnet where axions could be converted back into X-rays with energies up to 10 keV. The analysis of the data recorded with vacuum inside the magnet pipes resulted in the most restrictive experimental limit on the axion-photon coupling constant for axion masses up to 0.02 eV. In order to extend the sensitivity to higher axion masses, CAST continued the search for axions with a buffer gas inside the magnet pipes. We will present the first results on the 4He data taking as well as the system upgrades performed during last year in order to adapt the experiment for the 3He data taking. Expected sensitivity on the axion-photon coupling constant for the 3He data taking will be given.

15:25  Tokyo axion helioscope experiment (20'+5') (25') (files Slides pdf  ) Yoshizumi Inoue (University of Tokyo)

A search for solar axions has been performed using an axion helioscope which is equipped with a 2.3m-long 4T superconducting magnet, a gas container to hold dispersion-matching gas, PIN-photodiode X-ray detectors, and a telescope mount mechanism to track the sun. In the past measurement, axion mass up to 0.27eV have been scanned. After a moment of hibernation, a new stage of the experiment aiming at a higher mass range was reactivated. The helioscope has been upgraded to handle dispersion- matching gas (helium-4) of higher density. From late 2007 through this spring, the axion mass region around 1eV was newly explored, where the axions in the "photon- coupling vs mass" parameter region of the preferred axion models were newly searched. The latest result will be presented.

15:50->16:35    Summary - end of conference (Convener: Joakim Edsjö (Stockholm University) )
15:50  Summary of conference (40'+5') (45') (files Slides pdf  ) Paolo Gondolo (University of Utah)

Summary talk

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