Sensitivity analysis via adjoint Monte Carlo calculations of plasma focus irradiation of micro-silica beads in phantoms

One of the main issues in the analysis of the performances of radiation detectors via Monte Carlo methods is their sensitivity with respect to the various irradiation parameters: source intensity and position, detector effectiveness and sensitivity, etc. In the present work, the capability of a quite new Trueinvivo© micro-silica beads TLD has been analyzed from the point of view of the Monte Carlo modeling of the irradiation process and the possibility of a speed up of the calculations using accurate bias techniques based on the adjoint solution of the transport process. The source considered is a Plasma Focus device explicitly designed for cell cultures or “in vivo” tests. The experimental data and the pure analogic Monte Carlo simulation previously obtained results coming from dosimeters at different depth and positions in a PMMA phantom composed by slabs and built for hosting the TLDs, have been benchmarked with respect to the adjoint bias approach. The results obtained through different biasing techniques, backward particle transport analysis, Weight Windows and a discrete ordinate model solution, show how it is possible to optimize the Monte Carlo calculations with great effectiveness.