CMS Hadronic Endcap Calorimeter Upgrade R&D Studies

Due to an expected increase in radiation damage in LHC, we propose to transform CMS Hadronic EndCap calorimeters to radiation hard quartz plate calorimeters. Quartz is proved to be radiation hard by the radiation damage tests with electron, proton, neutron and gamma beams. However, the light produced in quartz comes from Cerenkov process, which yields drastically fewer photons than scintillation. To increase the light collection efficiency we pursue two separate methods: First method; is to use wavelength shifting (WLS) fibers, which have been shown to collect efficiently the Cerenkov light generated in quartz plates. A quartz plate calorimeter prototype with WLS fibers has been constructed and tested at CERN to show that this method is feasible. Second proposed solution is to treat the quartz plates with radiation hard wavelength shifters, p-terphenyl, or doped zinc oxide. Another calorimeter prototype has been constructed with p-terphenyl deposited quartz plates, and showed superior calorimeter capabilities. Here, the test beam, bench test and simulation efforts on these methods are reported. We also outline the future directions on these possible upgrade scenarios for the CMS HE calorimeter.