Performance of the First Version of VMM Front-End ASIC with Resistive Micromegas Detectors

This note describes the performance of the first version of a front end ASIC, VMM1, being developed for the Micromegas and sTGC detectors of the ATLAS New Small Wheel (NSW) upgrade. The VMM1 ASIC was designed by the micro-electronics group of the Instrumentation Division of Brookhaven National Laboratory. It contains 64-channels of linear, low noise amplifiers with adaptive feedback, charge amplitude peak detectors with time stamp. It can accept inputs of both polarities, features selectable gain and shaping time and has a built-in calibration system. It is designed to operate with micro-pattern gas detectors providing both trigger and tracking information. The VMM1 was tested during August 2012 test beam campaign at SPS/H6 beam line at CERN using micromegas detectors of the Muon ATLAS MicroMega Activity R&D program. We present here the VMM1 configuration, the software that was developed to achieve its operation, as well as the calibration procedure. Furthermore, we present the analysis performed with the micromegas detectors using the VMM1, reconstructing a charged particle hit in the uTPC and centroid mode. Finally, various trigger studies were performed using the VMM1 trigger functionality.