Development of a thermal ionizer as ion catcher

An effective ion catcher is all 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 front 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 call 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 Na-20 and Na-21. (c) 2008 Elsevier B.V. All rights reserved.