Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

58 Biennial Report 2005-072.4.3 Other Areas2.4.3.1 A study of elemental uptake in Radish grown near a Municipal Waste dumpingsite by EDXRF methodA Radish plant meant for human consumption along with the soil around root was collected fromnearby of a Municipal Solid Waste dumping site of a metropolitan city of Kolkata and analyzedfor a wide range of elements using an EDXRF system comprising a 109Cd source and a Si (Li)detector. To check the reliability of the system, first of all, a standard sample (Urban ParticulateMatter with SRM No. 1648) from NIST has been analyzed and it was found that results agreewithin 12% with the certified values. The three samples of soil, root and leaves were subsequentlyanalyzed using same procedure. Concentrations of elements with X-ray energies in the range of3-20 keV in the soil around the root and their uptake pattern by the root and the leaves wereestimated. It was found that the soil being contaminated the root and leaves had also taken uphigher concentrations of a few elements than normal, which is of grave concern for public health.D Gupta, JM Chatterjee, R Ghosh, AK Mitra, Subinit Roy, M SarkarNAP2.5 Simulation of Nuclear Detectors2.5.1.1 Development of neBEM solver using the ISLES libraryThe Poisson’s equation may be solved following Boundary Element Method (BEM) which can beviewed as numerical implementation of boundary integral equation based on Green’s formula. Incontrast to the Finite Element / Finite Difference Methods (FEM / FDM) where the completedomain needs to be discretized, in the BEM approach only the domain boundaries need to bediscretized. The resulting boundary elements are endowed with singularity distributions whosestrengths are obtained by satisfying given boundary conditions. A library of C function basedon exact closed-form integration of free-space Green’s function and its derivative due to uniformsingularity distribution on flat rectangular element was developed. This library was named as theInverse Square Law Exact Solutions (ISLES) library. Based on this library, a nearly exact BEM(neBEM) solver was also developed. To validate the solver, capacitances of unit square plate andcube, considered to be among major unsolved problems (in the sense that there are no analyticalsolutions available) in electrostatics, were computed to high precision and compared to availablenumerical results.Supratik Mukhopadhyay, Nayana MajumdarINO2.5.1.2 Improvement of the ISLES library to allow use of triangular elementsTriangular elements are known to be very efficient in modelling arbitrary geometries. In order toallow the use of such boundary elements in the neBEM solver, exact solutions of uniform singularitydistribution on triangular element was worked out. However, while the rectangular elements canbe of arbitrary size, triangular elements are restricted to be a right angled triangle of arbitrary size.It should be noted that this restriction does in no way limit the modelling capabilities of the solverbecause of the fact that any triangle can be split into two right-angled triangles. The validation of