Low-ZZ internal target from a cryogenically cooled liquid microjet source

We carried out an extensive investigation on the production of cryogenically cooled liquid hydrogen and helium droplet beams at the experimental storage ring at GSI with the goal to achieve high area densities for these low-ZZ internal targets. Our results show that an area density of up to 1014cm-2 is achieved for both light gases by expanding the liquid through sub-10 μmμm diameter nozzles. The achieved area density is comparable with the previous results for the hydrogen internal target and represents an improvement by about four orders of magnitude for the helium target.