by Mayda Velasco (Northwestern University)
The Large Hadron Collider (LHC) at CERN has just restarted and a new era in Particle Physics is about to begin. Several of the new Physics Beyond the Standard Model signals, like those for Dark Matter searches, will require a good understanding of the calorimeters in order to be able to trust the missing energy measurements and benchmark QCD processes, at the higher energies of the LHC, needed to properly estimate backgrounds.
I will discuss the readiness and the expected performance of the Compact Muon Solenoid (CMS) hadronic calorimeter (HCAL) at the LHC startup. The work is based on measurements made with cosmic ray muons and the LHC commissioning beam data taken in 2008 and 2009. Calibration parameters were extracted with this data, and the energy response of the HCAL determined from test beam data has been checked. Algorithms to identify sporadic uncharacteristic noise and treat a small number of malfunctioning calorimeter channels, that were first observed during commissioning, were tested. The design and performance of the time measurement technique and of the synchronization systems will also be presented.
Some examples of the physics topics to be pursued with the startup data and that are significantly dependent on the HCAL detector will be presented.