CEPC calorimeter software meeting
Time: 9:00-10:15, 9 Sep, 2020
Participants: 刘勇，刘春秀，李刚，李波，方文兴，齐宝华，王悦心，郭方毅，傅成栋，孙胜森，伍灵慧
indico: https://indico.ihep.ac.cn/event/12608/
Minutes (Linghui, Yong):
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Two pesentations:
- G4 full simulation of a single crystal bar
- ECAL geometry construction with DD4Hep
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Results from the G4 full simulation of a single crystal bar (YL, Baohua Qi)
- General info on the G4 full simulation
- Geometry: a single 40x1x1 cm^3 crystal bar, read out by 2 SiPMs at both ends
- Properties: BGO, SiPM, wrapping
- Optical photon processes
- Focus on the timing performance, esp. on the rise edge of detected photons
- Results in 3 (typical) scenarios
- Time stamps of detected photons (within the 0-30ns time window)
- Time stamps of the 1st detected photon per event (T_1st)
- Time differences of T_1st at both ends
- Discussions
- Wrapping: LUT models for surfaces (Chengdong)
- Tail in the T_1st spectra: originated from (slow) BGO scintillation, or geometric effect?
- Stimulated many discussions
- Timing resolution versus positioning resolution, at different incident positions
- Acceptance: larger SiPM?
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ECAL geometry construction with DD4Hep (Fangyi Guo)
- Implementation of crystal ECAL with DD4Hep:
- Discussions
- Tool(s) to check geometry overlap
- Gap: 0.7mm in the even layers
- Further discussions on the space needed by the hardware (SiPM, PCB, FE-electronics/ASICs, cooling)
- Endcap ECAL implementation? (Yong)
- Shengsen: not considered at this stage, curretnly focusing on the barrel performance
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Action items
- G4 full simulation
- Need to increase statistics: e.g. from 30 to 1k events
- 100% coverage with 10x10mm SiPM at both ends
- Modelling of ~2ns rise time of BGO scintillation -> check the impact on timing
- LUT models for the crystal wrapping -> collection efficiency, timing
- Timing resolution and #(detected photons) at different hit positions
- Investigate the origin of tails in T_1st spectra