Fission fragment escape from bare fission foils: Measurement and comparison with calculations based on the use of the LSS-theory for fission fragment range determination

The fission fragment escape fraction from bare ²³⁵U, 10% ²³⁹Pu/Al and 10% ²³⁷Np/Al foils were measured for four selected fission products, relevant for reactor neutron dosimetry, using the absolute radiometric technique. The escape fraction for the foils studied amounts up to 4% for the light fission fragments measured, a non-negligible correction in neutron dosimetry. Attempts for prediction of the fission fragment escape fraction, based on fission fragment range calculations using the LSS-theory accounting for Z₂-oscillations, were performed and compared to the measurements. Agreement ranging from 2 to 16% could be achieved. Furthermore, the experimental fission fragment escape fraction measurements were interpreted in terms of fission fragment range determination.