Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Nuclear Sciences 61conventional methods which the present solver is expected to handle gracefully.Nayana Majumdar, Supratik Mukhopadhyay, Sudeb BhattacharyaINO2.5.1.9 Computation of wire sag in a MWPCIn a large MultiWire Proportional Counter (MWPC), the sag of the long wires caused by theelectrostatic force acting among the closely spaced wires necessitates critical design optimization.For computation of electrostatic force acting on the wires, electric field and charge distribution onthe wires were estimated precisely using neBEM. The differential equation of the wire dynamicswas solved using three point Finite Difference Method (FDM) which led to a tri-diagonal matrixequation relating the wire deflection to the acting force. It was solved using a tri-diagonal matrixsolver to determine the wire deflection in anode and cathode planes as a function of voltage. Thenumerical method was validated by comparing the calculated gravitational deflection with theanalytical values.Nayana Majumdar, Supratik MukhopadhyayINO2.5.1.10 Implementation of RPC geometry in GEANT4GEANT4 version 4.8.2, patch 01 was installed and tested successfully on a Pentium IV machinewith 512 MB RAM running Fedora Core 7. The proper environment variables were set along withthe visual platform for necessary graphics. The detailed geometry of the RPC modules to be usedin INO CALorimeter (ICAL) detector was introduced in GEANT4 to simulate the experiment.Three dielectric layers representing a gas volume bound by two glass layers and readout strips oneither sides outside the glass layers were considered in the geometry. The readout strip geometrywas generated in a parametric way in order to enhance the efficiency of the computation.Supratik Mukhopadhyay, Nayana Majumdar, Sudeb BhattacharyaINO2.5.1.11 Simulation of electrostatic properties of MEMSThe application of ISLES library in simulating the electrostatic properties of Micro-Electro MechanicalSystem (MEMS) yielded precise results as observed in different geometric variations of aset of parallel plates or beam structures. In contrary to the requirement of special formulations inBEM to treat structures with micron order dimensions, the neBEM solver could seamlessly producethe normalized capacitance values matching closely with that yielded by other methods. The chargedensities on all the surfaces of the plates were computed. The effect of three dimensionality andfringe field effect were studied in detail when two narrow beams were considered. The capacitancesestimated by neBEM were compared to the available parametric results. The latter were found tobe inadequate to cover the wide geometrical parameter range.Supratik Mukhopadhyay, Nayana MajumdarINO