Roger Rusack – The University of Minnesota Upgrades to the CMS detector

Outline  This talk is the context of preparation for Snowmass. I want to motivate some technical developments for detectors at the high intensities that we will see at the energy frontier. 2 ANL lunchtime seminar.

Phase 1 ≤ 1.7 × cm -2.s -1 with 25 ns 2.0 × after LS2. Phase 2 5 × cm -2.s fb -1 ANL lunchtime seminar. 3

Upgrades for CMS Phase 2  Planned changes to the detector:  Replace tracker.  Track trigger.  Complete upgrade of trigger level 1 and HLT.  Likely changes of detector:  Trigger level 1 readout at 1 MHz.  Replace endcap EM calorimeter.  Replace active components of endcap hadron calorimeter.  Replace forward calorimeter 3.0 < η < ANL lunchtime seminar.

Major Sensor Issues  High Pileup:  events/bunch crossing with 25 ns Bx  Overlapping events in the hadron calorimeter.  High radiation levels:  In excess of neutrons/cm 2 in forward regions of the calorimeters.  Aging.  If we run until 2030, much of the existing detector will be more than 25 years old. 5 ANL lunchtime seminar.

Detector Goals  Maintain or improve the current performance of the detector.  Benchmark standard Higgs decay channels including Higgs → γγ  Improve jet tagging in forward detector for VBF.  In CMS investigating precision timing as a means of vertex mitigation. ANL lunchtime seminar. 6

Radiation Levels  Unprecedentedly high radiation levels in the forward direction. ANL lunchtime seminar. 7

Flux of neutrons after Phase 2. 8 >10 15 n/cm 2 ANL lunchtime seminar.

Flux in Forward Calorimeter 9 The neutron flux at 2,500 fb -1. >10 16 n/cm 2 ANL lunchtime seminar.

Ambitions:  In intermediate η’s  Detect both Čerenkov radiation and ionizing radiation and measure signal time all at multiple depths inside calorimeter.  We need for a scintillator based detector:  Detector Materials that are stable under these conditions and maintain optical transmission after flux.  Photodetectors that are rad hard.  Means to extract signal from the detector. ANL lunchtime seminar. 10

Possible Detector Materials.  What detector materials do we know that will work at these ultra-high radiation levels.  Amorphous silicon  Fused silica.  Some crystals.  What might work  Ceramics  Glasses.  Fluids.  Meta-materials.  …… 11 ANL lunchtime seminar.

Detector Materials  Amorphous Silicon.  Old idea for tracking dropped as charge collection efficiency was low and response to MIPs was small.  Calorimetry is a different problem.  See talk later in this session by Jim Kakalios on a/nc-Si:H.  Crystals  LYSO – good radiation tolerance reported.  Light output is high  Fused Silica  Very stable material under high radiation.  Excellent for Čerenkov.  Ceramics:  New ‘designer’ materials. Much progress in recent years: ANL lunchtime seminar. 12

LSO/LYSO ANL lunchtime seminar. 13 See talk by Renyuan Zhu at this meeting Stable band edge after p/cm 2 Less damage than PbWO 4

Ceramics ANL lunchtime seminar. 14

Photodetectors  Considerable progress in recent years in silicon APDs – now a mature technology.  Geiger Mode APD’s – SiPMs.  Low fab cost.  Several industrial manufacturers.  High gain and low amplification noise.  Rad hard ~10 13 n/cm 2.  Other materials.  GaAs APDs  High bandgap APDs - SiC, GaN, AlGaN. ANL lunchtime seminar. 15

GaAs Geiger-mode APD 16 First results from a GaAs SiPM photodetector Lightspin & UVA ANL lunchtime seminar.

High Bandgap APDs  Attractive since the material is intrinsically more rad hard.  Sensitive in the UV – solar blind.  Considerable interest in this UV detection in many other areas of research.  Astronomy  Čerenkov detectors.  Etc.  For UV sensors see talk by Dave Hitlin yesterday from intensity frontier. ANL lunchtime seminar. 17

Silicon Carbide  Bandgap of 4H-c SiC is 3.23 eV.  High bandgap material used in making LEDs, now showing up more in semiconductor and nan0-technology industry.  You can now buy JFETs and MOSFETs in SiC.  MOSFETs have been tested to 7.5 × neutrons/cm 2 and were operational.  Significant degradation at n/cm 2 seen by RD50.  Many interesting detector development possibilities. 18 ANL lunchtime seminar.

4H-SiC PIN480 Avalanche Photodiode: Recessed Window PECVD + Thermal SiO 2 SiO 2 n : + substrate n: 2000 nm, 4.5x10 18 cm -3 p: 200 nm, 2x10 18 cm - 3 p : 480 nm, - 1x10 16 cm - -3 p+:p+:p+:p+:200 nm, 1x10 nm, 1x10 19 cm -3 p-contact(Ni/Ti/Al/Au) n-contact(Ni/Ti/Al/Au) Thickness of p + : ~ 35 nm AR Coating (2300 Å) Joe Campbell – Electrical Engineering – University of Virginia

Quantum Efficiency 20 ANL lunchtime seminar.

Calorimeter Pileup Mitigation 21 ANL lunchtime seminar.

Precision Calorimeter Timing  For a luminous region distributed over ~ 10cm, collisions will be distributed over ~ 300ps  The TOF at the Calorimeter at  ~ 0 depends on the time of the specific collision  At Larger values of  the TOF depends both on the time and position of the specific collision 22 ANL lunchtime seminar.

Calorimeter Pileup Mitigation  Consider (for example) an EM pre-shower with 10~20ps TOF resolution for MIP’s and   Tracking identifies Z location of interesting collision  TOF of charged particles from that collision identifies time of interesting collision  Use Z location and time to select calorimeter clusters associated to interesting collision  Could result in similar effective pile-up as we have now. 23 ANL lunchtime seminar.

Timing in Calorimeter ANL lunchtime seminar. 24

4D Calorimeters ANL lunchtime seminar. 25 Can we make 4-D calorimeters in a high radaition environment?

How?  Various methods for this are being considered.  Fast crystal preshower.  Čerenkov detector.  Timing layer at shower maximum in EM calorimeter.  Direct measurement with SiPMs. ANL lunchtime seminar. 26

Summary  New sensor and photodetector technologies will be needed for the ambitious goals of the HL- LHC.  The time is soon to select out a few of the most promising ideas and invest in their develop them.  My bias is to invest where there are multiple gains inside and outside HEP. 27 ANL lunchtime seminar.