A Study of the Release Properties of Sn and SnS from an ISOL-type Target/Ion Source System

Radioactive ion beams (RIBs) provide a method for studying the properties of increasingly exotic nuclei. For many nuclei, the intensity of the RIB available in the isotope separation on-line (ISOL) technique is limited by the relatively long delay time in the target/ion source system (TISS). New techniques are needed to decrease this delay time, thereby increasing the intensity of the RIBs available for study.

The sulfide molecular sideband was discovered in 2001 as a way to greatly enhance the quality of Sn beams. Holdup measurements were performed at the Holifield Radioactive Ion Beam Facility (HRIBF) to determine the extent to which the delay of Sn in the TISS is improved by the introduction of sulfur. The results clearly demonstrate that SnS has a shorter delay time than Sn and indicate the improved release efficiency for short half-lives.

The results also indicate that improvements to the formation and release of SnS molecules from the TISS are possible. To this end, modifications were made to the standard HRIBF design to improve the formation and release of molecules from the TISS. The modified TISS design will provide greater control over the TISS parameters by enabling independent and controlled heating of the transfer line and by moving the gas feed line so that it is inserted directly into the target holder. With these improvements, it should be possible to improve the release of Sn isotopes in the sulfide molecular sideband by enabling the formation of the molecule earlier in the release process and by increasing the probability that the molecule will form.