Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

60 Biennial Report 2005-07dielectric geometry to that produced by several specialised BEM formulations. The detailed geometryof a trigger glass RPC with close resemblance to the detection module of INO (India-basedNeutrino Observatory) CALorimeter (ICAL) was studied for its potential and field configurationsconsidering multiple dielectric and conducting layers including readout strips.Nayana Majumdar, Supratik Mukhopadhyay, Sudeb BhattacharyaINO2.5.1.6 Simulation of electrostatic configuration of MPGDsThe neBEM solver was used to simulate the field configuration in several MicroPattern Gas Detectors(MPGDs) which are quite complicated in their geometry. MicroWire Detector (MWD),MicroStrip Gas Chamber (MSGC) and microMEsh GAs Structure (microMEGAS) were severalcases where the electric field and its variation with geometrical parameters in the detector volumewere simulated with the neBEM. The results showed overall close agreement to the availableFEM results. However, owing to the fundamental difference in two formulations, disagreement wasobserved in several regions where the neBEM seemed to yield more accurate results with comparativelyless computational expense due to the nature of its foundation formulations. The questionof improved accuracy is, however, still under detailed study.Nayana Majumdar, Supratik MukhopadhyayINO2.5.1.7 Simulation of weighting potential and field in TPCThe weighting field calculation turns out to be important when signal generation in a gaseousdetector is studied. The 3D weighting potential and field distributions were studied using theneBEM solver in a Time Projection Chamber (TPC) consisting of multiwire configuration. Analyticsolution for a simplified 2D strip detector with no anode wires or set of expressions used for padchambers obtained using conformal mapping method and semiempirical techniques are used asestimates for weighting field in TPC. While they turn out to be useful, they are limited by certainpresumed geometrical requirements which are unlikely to be met in real experimental situations.TheneBEM results with realistic geometrical aspects like presence of anode wires, cathode wire planeand closed geometry showed significant deviation from the analytical values in the avalanche region.Supratik Mukhopadhyay, Nayana Majumdar, Rob Veenhof†INO2.5.1.8 Simulation of weighting potential and field in RPCThe neBEM solver was employed to study the weighting potential and field distributions in a RPC.The solver was validated by estimating weighting potential for a single dielectric geometry for whichanalytic representations of the same could be calculated. Finally the neBEM results for a tripledielectric geometry were compared to the analytical integral representations of the potential andfield, carried out by using gaussian quadrature method. The weighting field computation for a RPCwith similar configuration of the detection module of ICAL detector was done with inclusion of finegraphite coating. The inclusion of thin surfaces like this usually generate numerical instability in