Licentiate Thesis: Time Calibration of the ATLAS Tile Calorimeter
Monday 15 June 2015
to 16:00 at
Björn Nordkvist (Stockholm University, Department of Physics)
The first few years of proton-proton collisions in the Large Hadron Collider at CERN has
certainly lived up to all the expectations physicists could have hoped for. Not only has the
ATLAS and CMS experiments independently of each other announced the discovery of the
long soughed Higgs boson, the per- formance of the experiments during the first few years is
also to be regarded as a success, setting new standards in experimental particle physics.
Behind this success is more than 15 years of development, construction, and commis- sioning
where calibration of the subdetectors take an important role.
In this thesis a method developed to synchronize the ATLAS Tile Calorimeter is presented.
The method is based on an integrated system of laser and need to take into account
propagation of clock signals as well as routing of several types of optical fibers sending light
pulses into the detectors photomulti- plier tubes. Analyzing the detector response of these
light pulses allows to compute timing corrections that are implemented into the detector readout
electronics. Using this method 99% of the 10000 channels of the ATLAS Tile Calorimeter
have been synchronized to within 0.6 ns in each Tile Calorimeter module and within 2 ns in
each Tile Calorimeters partition before beam data was available. The results from calibration
from module to module and the di↵erent independent sections of the calorimeter are presented
and compared with results obtained using LHC beam splashes.