Target Analysis for a TNS Nuclear Physics Experiment

Target Normal Sheath (TNS) acceleration is used at the Laboratory for Laser Energetics (LLE) to produce beams of deuterons with broad energy spectra ranging from 0 to 10 MeV. The deuterons emanate from a laser production target which then strikes a nuclear target. The subsequent nuclear reactions create radioisotopes which decay quickly with half-lives of a few minutes or less. Conventional rabbit or reentrant tube systems are too slow for an external decay counting system, thus the measurements are done in vacuo. During the summer of 2023 the Multi Tera Watt (MTW) Laser was used to generate a sub nanosecond laser pulse that illuminated the backside of a planer deuterated laser target. TNS deuterons were produced from the front side of the laser target which then struck a layered Tin, Lithium, and Titanium substrate nuclear target. Several nuclear reactions occurred in the lithium layer, one of them being the Li7(d,n)Li8 transfer reaction. Li8 decays via electron emission and has an 838.7(3) ms half-life. The electrons were counted with a Phoswich detector in situ and used to determine the reaction cross section. However, short lived isotopes produced in the protective Tin layer of the nuclear target can emit electrons of unknown number. To mitigate this contribution to the count rate, the Gamma-X counting system was used to determine the activation level of the Tin. The results are shown in the poster.