[Paper Review] Four-gap glass RPC as a candidate to a large area thin time-of-flight detector

V. V. Ammosov, В. А. Гапиенко+5 more|ArXiv.org|Apr 17, 2002

Particle Detector Development and Performance3 citations

TL;DR

This paper presents a four-gap glass resistive plate chamber (RPC) with 0.3 mm gas gaps as a thin, high-time-resolution time-of-flight (TOF) detector for particle physics. Tested with a 7 GeV/c pion beam, it achieved a time resolution of ~100 ps using strip readout over a 90 cm length, with a total detector thickness of ~12 mm, making it suitable for large-area, thin TOF systems in experiments like HARP.

ABSTRACT

A four-gap glass RPC with 0.3mm gap size was tested with hadron beam as a time-of-flight detector having a time resolution of ~ 100ps. A thickness of the detector together with front-end electronics is ~ 12mm. Results on time resolution dependently on a pad size are presented. This paper contains first result on the timing RPC (with ~ 100ps resolution) having a strip read-out. Study has been done within the HARP experiment (CERN-PS214) R&D work. A obtaned data can be useful if a design of a large area thin timing detector has to be done.

Motivation & Objective

• Develop a thin, large-area time-of-flight (TOF) detector for the HARP experiment with thickness <14 mm.
• Achieve high time resolution (~100 ps) using a four-gap glass RPC with 0.3 mm gas gaps.
• Investigate the dependence of time resolution on pad size and explore strip readout for improved scalability.
• Minimize the number of readout channels by using signal summing electronics and optimizing electrode geometry.
• Demonstrate feasibility of a thin, high-performance TOF system using high-resistivity glass RPCs.

Proposed method

• Constructed four-gap glass RPCs using 0.6 mm and 1 mm thick glass plates with 0.3 mm spacers made of fishing line.
• Used a tetrafluoroethylene-based gas mixture (C2H2F4/C4H10/SF6, 90/5/5) for stable operation in avalanche mode.
• Employed a 4-input pre-amplifier with 1 GHz bandwidth and a 50 ps bin-width TDC for time measurement, with signal summing to reduce channel count.
• Tested pad and strip readout configurations, with strip signals acquired from both ends and combined via time-averaging to improve resolution.
• Used a 7 GeV/c pion beam at CERN's T10 test area with scintillator hodoscopes for beam triggering and time reference (30 ps accuracy).
• Applied time-charge slewing correction using ADC data to improve time resolution by accounting for amplitude-dependent signal propagation effects.

Experimental results

Research questions

• RQ1 What is the time resolution of a four-gap glass RPC with 0.3 mm gaps as a function of pad size, and how does it scale with signal electrode area?
• RQ2 Can strip readout over long distances (up to 90 cm) achieve sub-120 ps time resolution in a thin RPC system?
• RQ3 How does particle rate affect time resolution and detection efficiency in a high-resistivity glass RPC?
• RQ4 Can signal summing electronics reduce the number of readout channels without degrading time resolution?
• RQ5 What is the intrinsic time resolution of the front-end electronics, and how does it contribute to the overall system performance?

Key findings

• The time resolution of the four-gap glass RPC follows a linear dependence on pad area: σt = 0.71 + 0.13×S ps, with S in cm², when using an 8-input summing amplifier.
• A time resolution of 110–120 ps was achieved for a 90 cm long strip readout with 2.5 cm width, using signals from both ends and time-averaging.
• The 3σ detection efficiency remained above 94% across all tested strip positions, with no significant degradation along the length of the strip.
• The intrinsic time resolution of the front-end electronics alone was measured at ~70 ps, with a 5–7% amplitude summing accuracy.
• Time resolution deteriorated with increasing particle rate, and detection efficiency dropped from 97% (small pad) to 94% (large pad) at higher rates.
• The system achieved a total thickness of ~12 mm (including chamber and front-end electronics), meeting the HARP experiment’s requirement for a thin TOF detector.