Extraction of diffusion coefficients from the study of Rb release in different carbon catchers

TL;DR

This study measures and compares the diffusion properties of rubidium in different carbon catchers, including nanotubes, to optimize catcher design for radioactive beam production.

Contribution

It introduces a method to extract diffusion coefficients of Rb in various carbon microstructures, aiding in designing more efficient catchers.

Findings

Diffusion coefficients were successfully extracted for Rb in different carbon catchers.

Aligned carbon nanotubes show potential for improved Rb collection and release.

Optimal catcher design involves small diameter, oriented nanotubes for maximum efficiency.

Abstract

New Target-Ion Source Systems combining a target and a catcher material are developed in the radioactive beam community, in particular at GANIL, in order to maximise the yield of very short lived atoms by minimizing the atom-to-ion transformation time. The aim of this study is to characterize the release properties of 81Rb collected on two graphite catchers and two carbon nanotube catchers. The release fractions were measured at various catcher-heating temperatures and then compared to the analytical expressions relevant to each catcher. This comparison led to the extraction of the pre-exponential factor (D0) and the activation energy (Eact) involved in the diffusion coefficient of Rb for three carbon microstructures. All these data allowed to define an ideal catcher which could be made of aligned carbon nanotubes of small diameter and oriented in order to collect all the 81Rb atoms produced by the target but also to release them efficiently.