The particle physics world is striving to detect the Higgs Boson, the
theorized last piece in the Standard Model puzzle. For this end, CERN
is building the Large Hadron Collider (LHC),
which will be the most powerful accelerator in the world when it goes
online in 2008. The LHC is a proton-proton collider, as opposed to
the particle-antiparticle collider that was its predecessor, the Large
Electron Positron collider (LEP). Four detectors are being built for
the new accelerator: the Compact Muon Solenoid (CMS); A Large
Ion Collider Experiment (ALICE); LHC Beauty experiment
(LHC-B); and A Toroidal LHC
Apparatus (ATLAS). All four follow the same basic design. They
measure the energy and position of particles via different layers
designed to detect particles of increasing energies. These layers are
called calorimeters and are referred to by the type of particles they
stop: Electron Calorimeter (ECAL); Hadron Calorimeter (HCAL);
solenoid; and muon chamber.
While at CERN, I assisted in the
calibration of CMS HCAL. In order to simulate realistic working
conditions, the HCAL crew had to make a small ECAL so that they could
calibrate HCAL as it would appear behind ECAL. Thus, they also needed
to calibrate their ECAL. I arrived during the first test beam run of
ECAL. We systematically shot the electron beam into each crystal of
ECAL; the data we collected were the results of these measurements.
Since test beam time is limited, we made cursory analysis of the data
to check that it was reasonable. The majority of the summer was spent
completely analyzing this data and similar data gathered when HCAL was
placed behind ECAL. In CMS, particles will pass through ECAL and hit
HCAL at a variety of angles. To simulate this effect at the test
site, ECAL was fixed while HCAL was placed on a movable table. The
table could be rotated horizontally and pitched vertically.
Systematically, we adjusted the table and measured the reaction of
HCAL (through ECAL) at various angles and through different ECAL
crystals.