Analytical model for release calculations in solid thin-foils ISOL targets

TL;DR

This paper presents an analytical model combining diffusion and effusion processes to accurately simulate isotope-release curves in solid thin-foil ISOL targets, validated against experimental data from ISOLDE.

Contribution

It introduces a novel combined analytical and Monte Carlo approach for modeling isotope release in thin-foil targets, improving prediction accuracy.

Findings

Good agreement with experimental release curves

Accurate reproduction of isotope yields

Effective modeling of diffusion and effusion processes

Abstract

A detailed analytical model has been developed to simulate isotope-release curves from thin-foils ISOL targets. It involves the separate modelling of diffusion and effusion inside the target. The former has been modelled using both first and second Fick's law. The latter, effusion from the surface of the target material to the end of the ionizer, was simulated with the Monte Carlo code MolFlow+. The calculated delay-time distribution for this process was then fitted using a double-exponential function. The release curve obtained from the convolution of diffusion and effusion shows good agreement with experimental data from two different target geometries used at ISOLDE. Moreover, the experimental yields are well reproduced when combining the release fraction with calculated in-target production.