Optimization of the double micro-mesh gaseous structure (DMM) for low ion-backflow applications

Abstract

Micro-pattern gaseous detectors with very low ion-backflow (IBF) provide cost-effective solutions to large-area and position-sensitive photon detection and readouts of high-rate time projection chambers. We have developed a double micro-mesh gaseous structure (DMM) with two avalanche stages, which has a low IBF ratio and high gain. The results of our previous work show that an IBF ratio as low as 0.05% was obtained and a gain of up to 3 × 106 was maintained for single electrons for the DMM. In this study, the DMM was optimized to further suppress its IBF by changing the size of gas gaps and the density of the wire mesh, and more significantly, by aligning the two mesh layers with a crossing angle. An IBF ratio lower than 0.025% was achieved after the structure optimization. There is also an indication that the IBF in the DMM may potentially be further suppressed.