[Paper Review] Beam studies of novel THGEM-based potential sampling elements for Digital Hadron Calorimetry

S. Bressler, L. Arazi+9 more|arXiv (Cornell University)|May 20, 2013

Particle Detector Development and Performance15 references4 citations

TL;DR

This paper presents beam test results of novel THGEM-based detectors with resistive anodes for digital hadron calorimetry, demonstrating 98% detection efficiency and average pad multiplicity below 1.2 in 5–6 mm thick configurations. The design enables stable operation at high rates with low discharge probability (~10⁻⁶ for pions) and effective discharge damping via resistive layers.

ABSTRACT

Beam studies of thin single- and double-stage THGEM-based detectors are presented. Several 10 x 10 cm^2 configurations with a total thickness of 5-6 mm (excluding readout electronics), with 1 x 1 cm^2 pads inductively coupled through a resistive layer to APV-SRS readout electronics, were investigated with muons and pions. Detection efficiencies in the 98% range were recorded with an average pad-multiplicity of ~1.1. The resistive anode resulted in efficient discharge damping, with few-volt potential drops; discharge probabilities were ~10^{-7} for muons and 10^{-6} for pions in the double-stage configuration, at rates of a few kHz/cm^2. These results, together with the robustness of THGEM electrodes against spark damage and their suitability for economic production over large areas make THGEM-based detectors highly competitive compared to the other technologies considered for the SiD-DHCAL.

Motivation & Objective

• To evaluate the performance of thin THGEM-based detectors as potential sampling elements for digital hadron calorimeters (DHCAL) in future linear collider experiments.
• To address the challenge of achieving high detection efficiency with low pad multiplicity in compact, robust, and cost-effective detectors for high-rate environments.
• To investigate the stability and discharge resilience of THGEM-based detectors under high particle flux, particularly in double-stage configurations with resistive anodes.
• To optimize detector thickness and gain stability for integration into large-scale DHCAL systems like SiD-DHCAL.
• To explore the feasibility of using THGEM-based detectors in both full-DHCAL and semi-DHCAL concepts via proportional response and dual-threshold readout.

Proposed method

• Fabricated 10×10 cm² single- and double-stage THGEM/SRWELL detectors with 1×1 cm² pads, using a resistive anode layer and 100 µm insulating gap to enable inductive coupling to APV-SRS readout electronics.
• Operated detectors in Ne/5%CH₄ gas mixture with 550 V on THGEM and SRWELL electrodes, achieving effective gains of ~2500.
• Performed beam tests at CERN-SPS using muons and pions at rates up to 3 kHz/cm² to assess detection efficiency, pad multiplicity, and discharge behavior.
• Used APV25 front-end electronics and SRS readout system to record cluster charge distributions and monitor voltage drops during discharges.
• Employed a segmented resistive layer with underlying copper grid to suppress charge spreading and prevent high multiplicity from electron diffusion.
• Compared performance across five configurations: two single-stage SRWELL and three double-stage THGEM+SRWELL, with total thicknesses of 5.8–6.3 mm.

Experimental results

Research questions

• RQ1 Can THGEM-based detectors achieve high detection efficiency (>95%) with low pad multiplicity (<1.2) in sub-6 mm thick configurations suitable for DHCAL?
• RQ2 How do double-stage THGEM+SRWELL configurations perform under high-rate pion beams compared to single-stage designs in terms of gain stability and discharge resilience?
• RQ3 What is the impact of micro-discharges (voltage drop <10 V) and large discharges (50–150 V) on signal cluster distributions and detection efficiency in THGEM-based detectors?
• RQ4 To what extent does the resistive anode layer effectively damp discharges and prevent signal degradation in high-rate hadronic environments?
• RQ5 Can the observed gain drop in single-stage configurations under high-rate pion beams be mitigated through design or operational optimization?

Key findings

• The Double1 configuration achieved 98% detection efficiency with an average pad multiplicity of 1.1 at 5.8 mm thickness, demonstrating high performance in a compact geometry.
• The Single2 single-stage configuration achieved 98% efficiency with a pad multiplicity of 1.15 at 5.8 mm thickness, showing excellent performance despite a gain drop under high-rate pion beams.
• No significant gain drop was observed in double-stage configurations (e.g., Double1, Double3) under high-rate pion beams, indicating improved stability compared to single-stage designs.
• Discharge probabilities were measured at ~10⁻⁷ for muons and ~10⁻⁶ for pions in double-stage configurations, with only rare large discharges observed on the top THGEM electrode.
• Micro-discharges (voltage drop <10 V) were observed in all configurations but did not affect cluster charge distributions or detection efficiency in double-stage setups.
• The resistive anode layer effectively quenched discharges, with few-volt potential drops, and prevented signal degradation, supporting robustness in high-rate environments.