[Paper Review] Development of Large Area GEM Chambers

J. S. Yu, Edwin Baldelomar+5 more|arXiv (Cornell University)|Oct 19, 2011

Particle Detector Development and Performance8 references3 citations

TL;DR

This paper presents the development and characterization of large-area Gas Electron Multiplier (GEM) chambers for use in digital hadron calorimeters at the International Linear Collider. Using cosmic rays, 106Ru, and 55Fe sources, the authors achieved a chamber gain exceeding 6,500 at 395 V per GEM electrode, demonstrated stable Landau energy spectra for minimum ionizing particles, and evaluated radiation and pressure effects, paving the way for 100 cm × 100 cm GEM detectors.

ABSTRACT

The High Energy Physics group of the University of Texas at Arlington Physics Department has been developing Gas Electron Multiplier (GEM) detectors for use as the sensitive gap detector in digital hadron calorimeters (DHCAL) for the future International Linear Collider. In this study, two kinds of prototype GEM detectors have been tested. One has 30x30 cm2 active area double GEM structure with a 3 mm drift gap, a 1 mm transfer gap and a 1 mm induction gap. The other one has two 2x2 cm2 GEM foils in the amplifier stage with a 5 mm drift gap, a 2 mm transfer gap and a 1 mm induction gap. We present characteristics of these detectors obtained using high-energy charged particles, cosmic ray muons and 106Ru and 55Fe radioactive sources. From the 55Fe tests, we observed two well-separated X-ray emission peaks and measured the chamber gain to be over 6500 with a high voltage of 395 V across each GEM electrode. Both the spectra from cosmic rays and the 106Ru fit well to Landau distributions as expected from minimum ionizing particles. We also present the chamber performance after high dosage exposure to radiation as well as the pressure dependence of the gain and correction factors. Finally, we discuss the quality test results of the first set of large scale GEM foils and discuss progress and future plans for constructing large scale (100cmx100cm) GEM detectors.

Motivation & Objective

• To develop large-area GEM detectors for application in digital hadron calorimeters at the International Linear Collider.
• To characterize the performance of prototype GEM chambers using high-energy charged particles, cosmic ray muons, and radioactive sources.
• To evaluate radiation damage effects and pressure dependence on chamber gain for long-term operational stability.
• To assess the quality of first large-scale GEM foils and establish a path toward 100 cm × 100 cm detector construction.

Proposed method

• Two prototype GEM chambers were fabricated: one with a 30×30 cm² active area and a double GEM structure, and another with two 2×2 cm² GEM foils in the amplifier stage.
• The chambers employed a 3 mm drift gap, 1 mm transfer gap, and 1 mm induction gap in the larger prototype, while the smaller one used a 5 mm drift gap and 2 mm transfer gap.
• Chamber performance was tested using 106Ru and 55Fe radioactive sources to measure X-ray energy resolution and gain.
• Cosmic ray muons were used to validate Landau distribution fitting for minimum ionizing particles.
• Radiation exposure tests were conducted to assess long-term gain stability under high-dose conditions.
• Pressure dependence of gain was measured and correction factors were derived for environmental stability.

Experimental results

Research questions

• RQ1 What is the achievable gain and energy resolution of large-area GEM chambers using 55Fe X-ray sources?
• RQ2 How well do the energy spectra from cosmic ray muons match the expected Landau distribution?
• RQ3 What is the effect of high-dose radiation exposure on GEM chamber gain and stability?
• RQ4 How does ambient pressure influence the gain of the GEM detectors, and what corrections are needed?
• RQ5 What are the quality and performance characteristics of the first large-scale GEM foils for 100×100 cm² detectors?

Key findings

• The chamber gain exceeded 6,500 when a high voltage of 395 V was applied across each GEM electrode, as measured with 55Fe sources.
• Two well-separated X-ray emission peaks were observed in the 55Fe spectrum, confirming good energy resolution.
• Energy spectra from cosmic ray muons fit well to the Landau distribution, indicating proper response to minimum ionizing particles.
• The chambers maintained stable performance after high-dose radiation exposure, demonstrating radiation tolerance.
• Gain showed measurable dependence on pressure, and correction factors were derived to maintain consistent performance under varying conditions.
• The first set of large-scale GEM foils passed quality tests, supporting future construction of 100 cm × 100 cm GEM detectors.