Development of a Cryogenic Helium Gas Target for Direct Reaction Studies

Helium-3-induced reactions can be used as tools to study properties of nuclei by selectively populating states via (³He,d), (³He,p), (³He,a), (³He,n), etc. At Louisiana State University, a gas target has been developed with a cryogenic cooling system to enable studies of ³He-induced reactions. The target windows are 7.5 um-thick Kapton with a 0.5-inch diameter aperture. The linear thickness may be varied by changing the window flanges. An areal density of 134 ug/cm² can be achieved with a 5-mm thick target filled with 500 Torr of ³He at 90 K. One example of a ³He-induced reaction is ⁷Be(³He,p)⁹B that can be used to populate states of ⁹B. The first-excited state of ⁹B has been studied and modeled for decades with little agreement on the energy and width of the state. Test experiments using the gas target as a ³He target have been conducted with ⁷Li and ⁷Be beams at Texas A&M University. The gas target performance and preliminary results from these (³He,p) reactions will be presented.