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

Wednesday 7 May 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

Here is the detailed meeting minutes from the TOF-General Meeting held on May 7, 2025

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1. Introduction (Satoshi Yano)

• Zhangbu was absent, so Satoshi led the meeting.

• Purpose: to prepare for the upcoming meeting with the ePIC Project Management (PM).

• Key topics for discussion:

• TOF timing resolution requirements and design

• Assembly and QA/QC framework

• Modular structure and interconnect method selection

• Meeting time coordination

 

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2. TOF Assembly Philosophy and Modular Structure (Satoshi Yano)

 

2.1 Assembly Philosophy

• The TOF detector design follows three main principles:

• Fulfill physics requirements

• Avoid acceptance holes (dead areas)

• Simplify assembly and maximize efficiency

• A modular structure is preferred over a monolithic (single-piece) approach.

 

2.2 Module Design and Quantity

• One module = 3 full sensors + 2 half sensors

• 1 half-stave = 8 modules → double-sided, 32 modules per stave

• Estimated total: ~4608 modules required

 

2.3 Assembly Flow

1. Module assembly at dedicated sites (e.g., Hiroshima, UCSC)

2. Half-stave assembly by connecting 8 modules on a 1.4 m stave

3. Tray integration to be conducted at BNL

 

2.4 Site Requirements

• Module assembly requires sensor handling jigs, wire bonders, glue dispensers, etc.

• Half-stave connection under study: wire bonding, ACF (Anisotropic Conductive Film), or TAB

• Final integration at BNL (tray + mechanical support)

 

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3. QA/QC Structure and Challenges

 

3.1 QA Responsibility and Discussion

• Sourav’s suggestion:

• QA for FPCs and interposers should be done at module assembly sites (e.g., Hiroshima, UCSC).

• Centralized QA/QC centers are preferable to maintain consistency.

• Simone and Matthew’s input:

• QA tools (e.g., network analyzers) are costly (up to $100k).

• Proper impedance and insertion loss tests are essential for high-speed signal lines.

 

3.2 Actions and Response

• Satoshi: will ask Takashi to give a presentation on QA procedure for FPCs.

• Proposal to invite international collaborators to Hiroshima for joint QA testing.

 

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4. Timing Resolution and PID Performance (Satoshi Yano)

 

4.1 New Simulation Conditions

• Following Eric’s feedback, Start timing resolution revised from 10 ps → 20 ps.

• Sensor timing resolution evaluated at 25, 35, and 98 ps.

• Results:

• 25 ps: Overall TOF ~34 ps → π/K 3σ separation up to 2.11 GeV

• 35 ps: Overall TOF ~42 ps → degraded separation

• 98 ps: Very poor PID performance, especially for K/p

 

4.2 Track Length Uncertainty (δL)

• Even ideal sensors/electronics can’t compensate if δL is large.

• PID performance is strongly affected by δL from tracking.

 

4.3 Yulia’s Comment

• δL must be studied with full Geant4 simulation.

• Requires collaboration with the simulation and reconstruction group.

 

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5. Sensor Test Status (Simone Mazza)

 

5.1 New Readout Boards

• 10 new 16-channel boards arrived.

• Some are used for pixel sensor testing; remaining ones available for strip sensors.

 

5.2 Gain Layer Uniformity (Depletion Voltage)

• 50 µm sensors: 55.3 ± 0.2 V (±0.4%) → extremely uniform.

• 30 µm sensors: 5.72 ± 0.13 V (±0.2%)

• Spatial variation suggests possible misalignment during ion implantation.

 

5.3 n+ Layer Resistance

• All measured values ~2.2 kΩ (design = 2.0 kΩ)

 

5.4 Strip Capacitance

• Large discrepancy between measurement (10s–100 pF) and TCAD simulation (~10 pF at 1 GHz).

• Likely due to measurement setup or pad geometry.

 

5.5 Upcoming Plans

• Repeat the tests for 30 µm and half-size sensors.

• Developing a probe card for CV (capacitance-voltage) measurements → potential for automation.

 

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6. Upcoming Meetings and Announcements

• Next TOF-General Meeting: May 14, same time

• Coordinators Meeting: May 8 (Thursday), 5:00 JST

 

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7. Action Items

1 meet with EIC project and ePIC managements

action items:
A. physics requirements:
BTOF time resolution requirements to overlap with hpDIRC
FTOF tracking position resolution: do we need 500um pitch?

B. BTOF stave modular?

C. mechanic design for FTOF

D. DSC coordination and meeting time (is it optimal?)

0507_BTOF_assembly.pdf

2 Time resolution requirements on BTOF

Speakers: Satoshi Yano, Satoshi Yano (Hiroshima University)

0507_TOF_Timing.pdf