Development of a thermal ionizer as ion catcher

TL;DR

This paper presents the development and testing of a thermal ionizer for radioactive beam facilities, offering advantages over gas-based ion catchers, especially for alkaline elements, with initial results on sodium isotopes.

Contribution

The paper introduces a thermal ionizer design for radioactive ion catchers, demonstrating its effectiveness and suitability for alkaline elements in beam facilities.

Findings

Successful construction and commissioning of the thermal ionizer.

First results obtained for $^{20}$Na and $^{21}$Na isotopes.

Potential advantages over traditional gas-based ion catchers.

Abstract

An effective ion catcher is an important part of a radioactive beam facility that is based on in-flight production. The catcher stops fast radioactive products and emits them as singly charged slow ions. Current ion catchers are based on stopping in He and H$_2$ gas. However, with increasing intensity of the secondary beam the amount of ion-electron pairs created eventually prevents the electromagnetic extraction of the radioactive ions from the gas cell. In contrast, such limitations are not present in thermal ionizers used with the ISOL production technique. Therefore, at least for alkaline and alkaline earth elements, a thermal ionizer should then be preferred. An important use of the TRI$\mu$P facility will be for precision measurements using atom traps. Atom trapping is particularly possible for alkaline and alkaline earth isotopes. The facility can produce up to 10$^9$ s$^{-1}$ of various Na isotopes with the in-flight method. Therefore, we have built and tested a thermal ionizer. An overview of the operation, design, construction, and commissioning of the thermal ionizer for TRI$\mu$P will be presented along with first results for $^{20}$Na and $^{21}$Na.