The University of Virginia CMS Effort

The University of Virginia High Energy Physics Group joined the Compact Muon Solenoid (CMS) experiment in 2005.  Currently there are four faculty (Professors Brad Cox, Sergio Conetti, Bob Hirosky, and Richard Imlay), two research scientists (Mike Arenton, Sasha Ledovskoy), two research associates (Marc Buehler, Duncan Brown) and four graduate students (Dave Phillips, Michael Balazs, Rachel Yohay, Dan Andelin) who are contributing to the UVa CMS effort.  The group has contributed to the Forward Pixel detector burn-in stations for the silicon electronics but our main effort at this point is on the PbWO4 electromagnetic detector (ECAL). 

We have been involved in several aspects of the ECAL detector.  In the 2006 and 2007 H2 and H4 test beam runs, which provided important data on the response of the ECAL to electrons and hadrons, we were test beam managers.  We also have built several testing stations to check the endcap supercrystals at every step of their preparation.  At the university, we are currently setting up a 4 T superconducting magnet to perform an exhaustive test of the vacuum phototriodes (VPT’s), which are the light sensing elements for the 14,000 crystal detector elements of the endcap ECAL.  We are responsible for a blue-orange LED flasher system and its electronics that will provide stabilizing light to the 14,000 VPT’s in the end caps as well as provide a stability monitoring and calibration system for these detectors. Finally, we are active in the installation of the ECAL endcaps.  We have primary responsibility for the installation of the electronics for the endcap detectors as well as the blue-orange LED flasher system.

In parallel with these hardware activities, we have been involved in the test beam analysis and the detector performance (DPG), physics object (POG), and physics analysis (PAG) levels in the development of the CMSSW version of the detector software.  In the DPG effort we have studied and simulated the stability of the VPT’s as well as studying resolution issues associated with the PbWO4 crystals.  In our POG effort we produced the CMSSW version of the shower shape algorithms.  Currently our PAG activities involve producing analysis software to extract supersymmetric (and eventually KK) signals form the CMS data.  In particular, we are presently studying the decay of neutralino into a gravatino + photon (GMSB model).  Related to these studies, we have been operating a local “tier-3” computing farm and have generated significant amounts of GMSB samples to facilitate analysis work in the SUSY/Exotics group and to debug CSA07 production requests.  We plan to build on our experience with the shower shape algorithms to detect both prompt (emitted at or near the primary vertex) photons and “off-axis” photons, which result from decay of long-lived neutralinos.