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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 - PowerPoint PPT Presentation
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CMS Hadron Calorimeter (HCAL)and the LHC Upgrade
Drew Baden (Maryland)Jim Freeman (FNAL)
NSF/DOE JOG - 11-Sep-08 1Drew Baden, U Maryland
Pedestal
Ion Feedback
Low Rate (discharges? …under study)
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
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 2
– Same as above – ameliorate low-rate non-beam related effects that compete with discovery cross-sections
• HPDs are noisy
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
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 3
Through thin part of PMT glass, ~130 GeV
Through thick part of PMT glass, up to few TeV!
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
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 4
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 lumensNSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 5
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
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 6
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…
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 7
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
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 8
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
NSF/DOE JOG - 11-Sep-08 Drew Baden, U Maryland 9
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