M.Sc. degree
Weizmann Institute of Science, Israel, 2017

Dan Shaked Renous

Supervisor: Shikma Bressler and Amos Breskin

Resistive-Plate WELL (RPWELL) gas-avalanche radiation detectors: Methods, characterization & properties

Keywords:

• Electron multipliers (gas)
• Gaseous detectors
• Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)
• Photon detectors for UV, visible and IR photons (gas) (gas-photocathodes, solid-photocathodes)

Abstract:

Micro Pattern Gas Detectors (MPGD) are suitable for numerous applications in particle, astro-particle, nuclear and applied physics. The Resistive Plate WELL (RPWELL) was designed to overcome one of the first challenges of the MPGD — the discharge problem. Since it was presented in 2013 by the Weizmann radiation detection group, the RPWELL detector has been investigated at the laboratory and at CERN test-beam facilities demonstrating broad dynamic range, efficient and stable discharge-free operation and stable high gain over time - in neon and argon based gas mixtures under X-ray source and under muon and high rate pion beams. In this thesis, two studies which continue the characterization of the RPWELL in Ne/CH4 (95:5) are presented as part of the ongoing research and development towards future applications. The first is a systematic comparison of RPWELL materials and production techniques aiming to overcome the weak points of the current FR4 and the Semitron ESD225® materials, which were used in the previous RPWELL studies. Configurations comprise Low Resistive Silicate (LRS) glass resistive plate, single sided THGEM electrode made of alumina and an epoxy-made electrode with a novel design of a step-WELL will be compared to the regular RPWELL realization. In the course of this study a systematic methodology for RPWELL characterization was developed, revisited and improved. In addition, a first long-term gain stabilization process (GSP) characterization was performed across days of spectra acquisition. This experiment showed intriguing trends of GSPs due to changes in the operation voltages and due to changes in the X-ray source rate in the different configurations. The second study presents a first UV photon detection characterization of RPWELL-based single and dual stage detectors.
Exciting results are presented as both configurations yield a clear single-electron avalanche size distribution, which shows the Polya distribution peak paving the way to an effective single UV photon detector.