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CMS Hadron Calorimeter (HCAL) and the LHC Upgrade Drew Baden (Maryland) Jim Freeman (FNAL). Areas of exposure in current HB/HE. Longitudinal segmentation in readout not currently implemented No correction for higher radiation damage in inner layers
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CMS Hadron Calorimeter (HCAL)and the LHC UpgradeDrew Baden (Maryland)Jim Freeman (FNAL) Drew Baden, U Maryland
Areas of exposure in current HB/HE • Longitudinal segmentation in readout not currently implemented • No correction for higher radiation damage in inner layers • Can vary weighting in separate layers, improves linearity of response and resolution • No redundancy to help ameliorate non-beam related signals • Electronics problems, beam gas/halo, cosmics, neutron albedo effects, and surprises • No timing capability in current HCAL Pedestal • Same as above – ameliorate low-rate non-beam related effects that compete with discovery cross-sections • HPDs are noisy Ion Feedback Low Rate (discharges? …under study) Drew Baden, U Maryland
Areas of exposure in current HF • PMTs will be degraded due to high radiation levels • Borosilicate glass of PMT faces are weakest points here • No redundancy and no timing capability in readout • At high luminosity charged particle flux may be unmanageable • Charged particles radiate Cerenkov light in PMT glass • HF is a very high gain calorimeter in a very harsh environment – small effects will become big problems at high luminosity Through thin part of PMT glass, ~130 GeV Through thick part of PMT glass, up to few TeV! Drew Baden, U Maryland
Physics Capability • Ultra-high-pt phenomena • “Raw” distributions are dominated by non-beam-crossing-related effects • Cosmics, halo, beam-gas, detector • This will probably not become less critical at high luminosity! • It is only via sufficient redundancy that we can deal with this Drew Baden, U Maryland
Upgrade in a Nutshell • Increase longitudinal segmentation in HB and HE • Add redundancy, survive high luminosities, and surpass current HCAL capabilities • Self-imposed constraint, keep present digital fiber plant • $ savings funds, take advantage of unused bandwidth capability, avoid recabling • Replace HPDs (HB/HE) and PMTs (HF) with new technology • Investigate SiPMs in HB/HE • Were not available ~10 years ago when choice of HPDs had to be made • They are rad hard, cheap, small, flexible, higher gain, quieter • Will allow us to increase segmentation, add timing capability, avoid HPD • Improves ability to reject backgrounds, reduce out-of-time pileup • At SLHC luminosities will have 400 events per crossing, way beyond original CMS specs • Investigate multi-anode PMTs, timing, redundancy, etc in HF • SiPMs would be too expensive, rad environment might be too harsh • “Throw the book at it”. May work if occupancies are not 100% at high lumens Drew Baden, U Maryland
Optimize Technology Opportunities • Current scheme in HB/HE/HO to change scintillator light to electrical signals is very complex • Physical mechanisms are labor intensive and delicate • Fiber electrical details are complex • SiPMs allow vast simplification • Connector from detector has the fibers, plugs into coupler unit • Can replace with cheap 1x1 mm2 SiPM array, established technology, very cost effective Under investigation – very exciting possibilities for a better, cheaper, more reliable upgrade to current design that meets our requirements Drew Baden, U Maryland
Front End/Back End • FE Scheme, HB/HE (HF has similar considerations): • Change to SiPMs • Add channels (segmentation) and timing • Keep current digital fibers, therefore transmit at higher rates • This means that the “back-end” has to change • New receivers means new HTRs • Current HTRs use obsolete fiber receivers and deserializers, no upgrade path without building new boards • The good news is that this is easier with current FPGA capabilities • Take this opportunity to consider • Moving away from VME? (uTCA, telecommunications standard, is the current favorite) • Completely new HCAL/ECAL relationship? • Scheduling is going to be important. Need to address now. • Particularly if we go to a new uTCA architecture in much of CMS. • What goes on at Pt5 and what goes on at 904 prior to installation… Drew Baden, U Maryland
Goals of This Workshop • Converge on what we want to do • Review current status and R&D plans • Identify outstanding issues and who will work on them • This is critical. We need new people. There is not a lot of time • Identify resources required for near term R&D • Understand the budget and schedule for upgrades • And be ready to formulate a proposal in the spring • In concert with rest of USCMS and CMS Drew Baden, U Maryland
Organizing the Work • Front-end organized by Jim Freeman and Chris Tully • Back-end organized by Drew Baden and … • Coupling? • If we go with SiPMs (and we will if we con convince ourselves that we can do it) we will definitely have to rebuild back-end • However people are investigating a more radical back-end upgrade path • More in concert with ECAL, create “Calorimeter Electronics” effort, in concert with evolution of Level 1 (Jeremy will present) • Bottom line(s): • We don’t have a lot of time • We don’t have infinite resources • We should get all good ideas on the table • We want to have an HCAL that not only survives high luminosity but actually works better Drew Baden, U Maryland