Performance of a resistive micro-well detector with capacitive-sharing strip anode readout

Abstract

The present study is carried out to demonstrate a new type of high-performance readout structure with low readout channel count developed for large-area micro pattern gaseous detectors. The structure exploits capacitive coupling between a vertical stack of 5 μ m thick copper pad layers sandwiched between 50 μ m thick polyimide foils to simultaneously transfer and spread the avalanche charges from the gaseous detector’s amplification structure to several strips or pads in the anode readout plane. The unique feature of the lateral spread of the avalanche charge size on several readout strips or pads is possible owing to well-defined configuration and sizes of the pads in layers of the vertical stack. This is known as a “capacitive-sharing” readout structure and this opens the door for high spatial resolution performance with low readout channel counts for large-area Micro Pattern Gaseous Detectors. Capacitive-sharing readout structures are fabricated using standard printed circuits boards manufacturing process. The concept is highly versatile as it can easily be implemented in any type of Micro Pattern Gaseous Detector’s amplification structure (Gas Electron Multipliers, micro-mesh gaseous structures, resistive micro-well detectors) and with a wide range of readout patterns (pads, strips, zigzags etc.). The technology also has a high degree of flexibility in terms of readout segmentation (pads or strip) pitch, with minimum impact on spatial resolution performances. The present study provides a detailed description of the capacitive-sharing readout concept and discusses a small resistive micro-well detectors prototype assembled with a two-dimensional capacitive-sharing strip readout structure as a proof of concept and with strip pitch of 800 μ m in both X and Y direction. The prototype was characterized in electron beam in the Hall D Beam Test setup at Jefferson Lab and a spatial resolution of (60 ± 1) μ m was achieved for both X and Y strips with an efficiency of (98.0 ± 0.9) % at the plateau and a signal arrival time jitter between neighboring strips less (6.00 ± 0.04) ns. Finally, we explore new ideas to expand the concept of capacitive-sharing readout structures to large particle detectors for future large scale particle physics experiments.