Paper Title
Defect Analysis Of Heavy Ion-Irradiation Of Polyethylene-Martian Regolith Composites

We have used SRIM-2013 computer code to estimate the irradiation parameters such as cascade displacements, stopping powers, lateral/longitudinal straggling, ionization, and the defect concentrations in polyethylene and its composites with Martian Regolith (MR) subjected to irradiation by 600 MeV/u 56Fe+-ions. Our previously reported Positron Annihilation Lifetime Spectroscopy (PALS) studies showed larger variations in positron lifetime parameters with increasing irradiation dose (10, 32, 64 Gy) for polyethylene compared to its MR composite. TRIM analysis showed that most of the energy transferred to target by 56Fe+-ion is through ionization (electronic) and mall part via displacements and phonons (nuclear). The production of total vacancies/displacements is higher in MR composite compared to polyethylene, but the affective vacancy concentration is higher in polyethylene due to larger lateral straggling. The dissipated energy density is also higher in polyethylene. H-vacancies to C-vacancies ratio is 2.5 for polyethylene and 1.8 in polyethylene+MR composite with higher number of H and C vacancies in polyethylene. Loss of H-atoms from matrix due to irradiation and their effect on chemical transformations are discussed to explain the differences observed in nanoporous free volume and flexural stress. Polyethylene+MR composite seems to be more resistant to heavy ion irradiation compared to polyethylene. IndexTerms- Ion-Irradiation, Polyethylene Composites, Martian Regolith, Sirm Analysis.