A MICROMEGAS chamber with embedded DIRAC ASIC for hadronic calorimeter

Abstract

DIRAC is a 64 channel mixed-signal readout integrated circuit designed for Micro-Pattern Gaseous Detectors (MICROMEGAS, Gas Electron Multiplier) or Resistive Plate Chambers. These detectors are foreseen as the active part of a hadronic calorimeter for a high energy physics experiment at the International Linear Collider. Physics requirements lead to a highly granular hadronic calorimeter with up to thirty million channels, and probably only one or two bits channel readout (so-called digital calorimeter). The DIRAC ASIC has been especially designed for these constraints. Each channel of the DIRAC chip is made of a 4 gains charge preamplifier, a DC-servo loop, 3 switched comparators and a digital memory, thus providing additional energy information for a hit. A bulk MICROMEGAS detector with embedded DIRAC ASIC has been build. The tests of this assembly, both in laboratory with X-Rays and in a beam at CERN are presented, demonstrating the feasibility of a bulk MICROMEGAS detector with embedded electronics. The second version of the ASIC, with improved noise and additional functionalities, has just been received and preliminary results are reported in details.