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AC-LGAD working group meeting
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US/Eastern
Description
Meeting for all AC-LGAD subsystems to discuss topics of common interest (e.g. sensors, ASICs, testbeams).
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https://bnl.zoomgov.com/j/1617546118?pwd=qNzxLqF8Q4Mj3RerAZdVSELzEgEQzV.1
General agenda:
-
Institutional updates (if any).
- QA plans and follow-up from Glasgow
- Testbeam discussion - plans for DESY in Spring
Attendees: Alex Jentsch, Xuan Li, Alessandro Tricoli, Gabriele Giacomini, Grigory Nigmatkulov, Jenni Ott, KaiYu, Kentaro Kawade, Masashi Kaneta, Satoshi Yano, Simone Mazza, Takashi Hachiya, Yubo Han, Zhangbu Xu
Roundtable updates
- Simone (UCSC)
- See slides from last TOF meeting for updates on testing with strips.
- Alex (BNL)
- Many updates --> progress on EICROC0A and EICROC1 testing, new boards working, and EICROC1 wire-bonding to new boards almost complete.
- Xuan Li (LANL)
- Presentation of past work on AC-LGADs and potential contributions to a future testbeam at DESY.
- Availability of CAEN digitizers which can be helpful for a testbeam setup.
- Satoshi (Hiroshima)
- Plan to submit proposal for KEK beam time in Nov/Dec 2026 --> focus on strips + FCFDv1.2 (backup plan for Feb/March).
- Working with other experiments to get a telescope setup.
- Finalizing sensor parameters for next production (meeting with HPK is next week). --> EIC-JPN JFY25 vs. eRD112 FY23, if the former cannot meet the 35ps spec, go with FY23 parameters for production.
- Simone:
- The 2024 production is essentially identical to the 2023 production --> is the issue due to the move from small to large sensors?
- From Zhangbu: is the 55ps spec final? --> no, the analyses need to be completed to finalize the result.
- FY23 studies --> working on a study where only every other strip is connected (to simulate a 1mm pitch vs. the 500um pitch) to try and make comparative tests, results soon.
- Issue with higher p++ doping is that is might not give you more gain, the main thing you do is reduce the breakdown voltage --> can reduce the maximum electric field in the bulk and make the sensor perform worse. Perhaps trying the opposite, less p++ doping, allow breakdown voltage to be higher. Higher doping tried previously and indeed reduced the breakdown voltage and the drift never got a chance to saturate.
- Alessandro agrees, ~ 200V is an optimal voltage to make sure you saturate the electron velocity, so current doping done by Hammamatsu seems close to optimal. Once drift velocity is saturated, increasing the bias voltage has diminishing returns.
- Alessandro: do funds exist from Japan to try these different LGAD variations? --> Yes, and we need to get the production started very soon.
- Should ensure we don't duplicate previous work, and should discuss the optimal design before the production is submitted.
- Jenni: still want to keep some baseline sensor parameters to reproduce previous results (e.g. FY23 parameters).
- Simone (shared some plots showing different gains for different breakdowns) --> All show more or less the same level of gain (around 50) --> doping concentration really only affects the breakdown voltage. --> even the timing resolution is still very similar.
- Grigory (UIC)
- IV scans for full-size strip sensors. --> scans look good.
- FNAL board damaged due to detached cap --> looks like some arcing happened.
- Alex will ship some new preamp boards to Simone, Grigory, and Jenni next week.
- Jenni (Hawaii)
- Work progressing on PED request to get EICROC probing setup going.
- Christophe sending ALTIROC wafer (8") to Jenni to help with probe station setup.
- Alex: what is meant by ePIC framework version? --> use any craterlake config, will work on getting RACF account.
DESY testbeam potential in Spring
- From Grigory: application process will open ~ September, and then it will take about 4 weeks for the schedule to be released after that.
- Max of two weeks.
- Focus will be on pixel sensors + EICROC.
- TB21 should be the goal, used by Satoshi last time.
- Aim for mid-Spring (sometime between March and May).
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