Ph.d. degree
Weizmann Institute of Science, Israel, 2018

Luca Moleri

Supervisor:Shikma Bressler, Amos Breskin

Development of large-area gas-avalanche Resistive-Plate WELL detectors: potential sampling elements for digital hadron calorimetry

Keywords:

• Micropattern gaseous detectors (THGEM)
• Calorimeters
• Performance of High Energy Physics Detectors
• Detector design and construction technologies and materials

Abstract:

The construction of new accelerators goes along with the development of advanced detectors and instrumentations. Since many scenarios of new physics Beyond the Standard Model (BSM) of particles involve hadronic-decay channels, efforts are made to develop modern calorimetry systems. All experiments designed for future linear colliders foresee the implementation of a (semi-)Digital Hadron Calorimeter ((s)DHCAL) as a key-element for their expected performance.
The present work targeted the development of a large-area, robust, thick detector concept, suitable as sampling element in a sDHCAL and for other applications requiring particle imaging at moderate, sub-mm spatial resolution over a large area.
As a solution, the few-mm thin Resistive-Plate Well (RPWELL) sampling element concept, developed at WIS, was suggested: a single-sided Thick Gas Electron Multiplier (THGEM) electrode coupled to the readout anode through a highly Resistive Plate (RP).
Several detector prototypes, reaching a size of 500 x 500 mm2, were built. They incorporated either Semitron ESD225 acetal, or silicate doped-glass Resistive Plate (RP). Methods were developed for e ectively coupling the RP to the readout anode.
The detector prototypes underwent various systematic investigations - both in the laboratory, and with muon and high-rate pion beams at the European Organization for Nuclear Research (CERN)-Super Proton-Synchrotron (SPS).The presented results allow for a deeper understanding of the RPWELL detector concept and properties. Moreover, they are essential for optimizing the design of future large-area prototypes and their performances for di erent applications. Their main properties are: stable operation with Ne/(5%)CH4, Ar/(5%)CH4 and Ar/(7%)CO2 gas mixtures. High efficiency (>98%) at low average pad multiplicity ( 1.2). Position resolution of 0.28 mm. These properties make the RPWELL a competitive technology, compared to other candidate sampling elements for sDHCAL or Digital Hadron Calorimeter (DHCAL).
Based on this study, the preferable RPWELL detector configuration for future (s)DHCAL would include a 3 mm drift gap, single-sided THGEM electrodes with segmented holes pattern (segmentation similar to that of the readout anode), Semitron ESD225 or doped silicate-glass resistive-plate coupled to the anode through graphite/epoxy.
The preferred operation gas mixture is the non-ammable Ar/(7%)CO2.
Future RPWELL-based (s)DHCAL prototypes will be read out by the (s)DHCALdedicated MICROROC readout electronics - the next step towards the integration of RPWELL sampling elements into a full (s)DHCAL prototype.