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