Evolution of the shape of fission fragment energy spectrum with absorber thickness in two different media and effective charge correction

The energy loss behavior of fission fragments (FFs) from Cf-252(sf) in thin Mylar (H8C10O4) and Aluminium absorber foils has been revisited. The aim is to investi-gate the observed change in the well-known asymmetric energy of spontaneous fission of Cf-252 as the fragments pass through increasingly thick absorber foils. Two different types of absorbers have been used: one elemental and the other an organic compound. The stopping powers have been determined as a function of energy for three fragment mass groups with average masses having < A > = 106.5, 141.8, 125.8 corresponding to light, heavy and symmetric fragments of Cf-252. The energy loss data have been com-pared with the predictions of SRIM 2013 code. The best representations of the data have been achieved using the effective Z correction term in the stopping power relation from the classical Bohr theory. Using the effective charge (Z(e)(ff)) in the stopping power relation in the classical Bohr theory best describes the stopping power data. Spectrum shape parameters, subsequently, have been extracted from the energy spectra of FFs for different foil thicknesses. The effective charge (Z(e)(ff)) correction term determined from the stopping power data is then used in the simulation for the absorber thickness dependence of the shape parameters of the energy spectrum. The present simulation results are compared with the TRIM prediction. The trends of the absorber thickness dependence f the spectrum shape parameters, for both Mylar and Aluminium, are well reproduced with the present simulation.