General EEEMCal Meeting Summary 5/31/24

PARTICIPANTS: Justin, Carlos, Douglas, Richard, Renee, Rosi, Tanja, Hamlet, Larry, Casey, Dmitry, Crytur-USA, Hrachya, Joerg,

BEAM TESTS

• DESY beam test slot tentatively assigned for October 28 - November 11

• still some administrative approvals needed, but beam test time seems set for this time frame

• MIT will send a 5x5 prototype

• includes 25+5 crystals
• PMT readout
• modifiable for other types of readout

• IJCLab-Orsay has a 5x5 prototype

• needs crystals (borrow from JLAB/universities)
• needs SiPMs
• ASIC readout chain for 4 SiPM/crystal
• could read 25 channels with fADC

• fADC readout

• in principle can be done with IJCLab-Orsay prototype, but have no fADC system
• perhaps could be done with MIT prototype

• Crytur is building a 5x5 prototype

• uses SiPMs
• one goal is to study compensation for nonlinearity

• In-person participants at DESY anticipated

• MIT: 2
• Orsay: 1-2
• Crytur: 1-2
• AANL: 1-2
• CUA: 1

• Action item:

• further develop the detailed run plan
• prepare/select crystals to send to Orsay

SIPM SELECTION FOR BEAM TEST

• By cost the 3mm SiPMs (both 10um and 15um) are cheaper than 6x6mm SiPMs

• 3mm: $53/SiPM
• 6mm: $125/SiPM

• Best would be to do a test with all four choices of SiPM, however, given the constraints of the beam test need to make a decision on a "favorite" earlier. The "favorite" may change after the fall beam test.

• In general, at low energies photostaticstics are most important (Crytur modeled SiPM characteristics and found PDE difference - points to 15um SiPM). Lowest energy expected 100 MeV for shower (per tower 5 MeV). At higher energies (EIC mostly at GeV scale) the constant term dominates, which is dominated by linearity. Larger 6x6mm SiPM have higher capacitance. Putting SiPMs together into a matrix (needed for large area homogeneous blocks) may further increase capacitance. Could point to 3mmx3mm size as the best choice. Easier to combine into a matrix.

• Overall:

• PDE for 15um is significantly higher
• Higher gain/photodetection efficiency - almost factor of two - for the 15um SiPMs. Slightly more nonlinear, but should be able to compensate
• Good to understand the nonlinearity even before combining SiPMs
• Regarding compensation Crytur had discussions at CALOR24 about that: Papers on

• 15um SiPM + PWO and non-linearity compensation options presented at CALOR24. Paper 1, Paper 2

• Also important: dark current increase

• Action item:

• Further discuss "favorite" SiPM selection at 5 June readout meeting
• Develop a plan for procuring SiPMs for the beam test

SIPM IRRADIATION STUDIES

• Carried out with 60 MeV proton beams

• Selected dose rates for the inner most crystals - worst case scenario

• Initial results from irradiation studies

• dark current incease from no irradiation to Year 10 irradiation - three orders of magnitude increase, which will increase the low enery threshold. May need to replace innermost SiPMs every year or have a mechanism for recovery. How many SiPM rings are impacted? What recovery mechanisms are available?

• at first overall look, there does not seem to be a huge difference in dark current increase between the SIPM

• Action items:

• continue the detailed analysis of the irradiation data
• look into annealing of SiPMs - sPHENIX uses thermal annealing (may discuss more with Oleg, Craig, Sasha, et al.)
• how does dark current increase/dose vary with radius?

TESTBENCH AND SIMULATIONS

• Simulation studies needed

• one study to perform is the uniformity of light collection at the back of the crystals. Hopefully, light is very uniform, and the positioning of SiPMs will not introduce any systematics or degrade the resolution. So far no quantitative study

• simulation for the upcoming beam test - SiPM matrix + crystal modules

• Test bench setup

• start developing initial test bench setups, e.g., light yield or dimension/visual inspection setup

• Crystals for test bench setups - how many can be loaned?

OTHER

• Received a request from project for PED items with cost&schedule estimate for the scope ending with the SiPM boards

• This request for PDE work includes what is needed to accomplish the final design

NEXT MEETING: 14 JUNE AT 8AM ET