OPTIMIZATION ALGORITHM FOR ELASTIC RECOIL SPECTRA SIMULATION

An optimization procedure is presented for Simulating a proton elastic recoil spectrum induced by low energy helium ions. This optimization is made according to the Poisson maximum likelihood chi-square definit ion. The procedure is theoretically developed and the convergence demo nstrated so that the optimum values can be obtained rapidly. In order to give reliable results, this algorithm requires knowing the constitu ents of the target for stopping power evaluation. This procedure uses the new scattering cross section values for helium-proton collisions. These cross section values are calculated from the optimum solution fo r phase shifts analysis which were reported in a previous paper. This algorithm allows a simple confident treatment of recoil spectra and sh ows rapid convergence for practical problems. This optimization is a p rogression of the simulation algorithm which is incorporated as part o f an ERD analysis software code (GABY) on a PC. Several targets such a s polystyrene thin sandwich samples deposited on silicon substrates we re used in order to check the validity of this procedure.