ePIC AC-LGAD TOF DSC Weekly Meeting Wednesday (10:30AM)

Wednesday 6 Aug 2025, 10:30 → 13:38 US/Eastern

https://bnl.zoomgov.com/j/1617546118?pwd=qNzxLqF8Q4Mj3RerAZdVSELzEgEQzV.1 (zoom link)

Zhangbu Xu (Kent State University), Satoshi Yano

eic-projdet-tofpid-l@lists.bnl.gov

zoom link

1 Beam Test at Jlab and DESY updates

JLab and DESY beam tests go well

Satoshi reported beam test in Japan is approved to be in January or March. The proposal is for a week of beam time at Tohoku University

2 PED 2026

https://docs.google.com/document/d/1_7CQUjbQNwc8BXJRIVZw9mbGGia9fScGteqx8tj-w5o/edit?pli=1&tab=t.0#heading=h.n3rl7f6hkly1

3 November review (PDR)

4 mechanic design updates?

5 Questions and Summary of critical simulation items from management

QUESTIONS from John, with preliminary answers from Kentaro and comments from Zhangbu.

1. What is the ultimate timing resolution needed?

Based on our simulation studies (where full digitization has not yet been implemented), we concluded that a total timing resolution of 44 ps satisfies the requirement by a narrow margin for the Barrel ToF.

This 44 ps includes contributions from:
- the sensor timing resolution,
- electrical jitters, and
- the finite T0 resolution. XZB: I feel that we should not include
t0 as part of the timing resolution of TOF system, most of the
measurements DO NOT require t0 as necessary for TOF. Only single
hadron in exclusive process needs t0

A similar study for the fToF is currently underway and will be completed soon.

1. Does the fToF contribute to the tracking, and if yes what requirements does this set?
   The fToF is not designed as an ultra-thin detector;
   It has a material budget of approximately 7%, which is already included in the GEANT4 simulation.
   Although we have not conducted a dedicated study on its impact on the dRICH tracking performance, there are currently no concerns raised by the dRICH group.
   XZB: FTOF did not have the correct position resolution in the simulation, but was fixed. next step is to be included in the tracking simulation to study the impact.

2. What is the allowed material budget not impacting the performance of the other detectors.

This is one of the most critical issues in the Barrel ToF design and will require negotiation with the TC.

Our simulation studies suggest that increasing the material budget from the initial concept (<1%) to 6–7% does not significantly degrade the tracking performance. XZB: we need to understand impact on other detector BEMC. probably 2-3% is achievable and also minimum impact on
energy resolution of BEMC.

Specifically, the tracking resolution was found to worsen from 0.6 mrad to 0.7 mrad when the material budget is increased to 6–10%.
This change does not have a significant impact on the hpDIRC tracking performance.

Therefore, we believe that allowing a 6–7% material budget for the bToF is acceptable.
This budget is important for a realistic mechanical design, including support structures, coolant fluid, readout FPCs, and other components.

1. What is the acceptance needed for the physics, do small acceptance gaps between modules have a negative impact

We have not yet conducted such a study.
To evaluate this, we will need to implement the acceptance gaps into the ePIC simulation.