EXPERIMENTAL AND THEORETICAL RESULTS FOR STOPPING POWER OF PROTONS IN HAFNIUM

A. M. P. MENDEZ; P. MIRANDA; D. M. MITNIK; C. C MONTANARI; J. E. MIRAGLIA

Antibes

Congreso; 24th International Conference on Ion Beam Analysis; 2019

Societe Francaise du Vide

Stopping power cross sections of Hafnium for 0.3 to 2.5 MeV protons have been measuredusing the transmission method [1]. The measurements were made at 2.5 MV Van de Graffaccelerator of the Laboratory of Accelerators and X-Ray Diffraction in Lisbon, Portugal.The overall energy resolution of the detection system was about 15 keV relative to 5.486MeV alpha particles from a 241Am source. The stopping material was a Hafnium foil withnominal thickness of 1.0 μm and 99.95% purity. A precise thickness value was determinedto be 0.920±0.046 μm.The theoretical description involved the calculation of the relativistic wave functions andbinding energies of Hf, which proved to be different from the non-relativistic ones, even forthe outer shells. We considered 4 electrons per atom in the free electron gas (FEG), andrs=2.14 a.u. The shell-wise local plasma approximation (SLPA) [2] was employed todescribe the energy transferred to the bound 1s-4f electrons, and two different models for theFEG: the screened potential with cusp condition (SPCC) [3] for energies below that of theplasmon excitation, and the dielectric formalism, for energies around the stopping maximumand above.