Development of internal jet targets for high-luminosity experiments

We report on recent developments of the internal supersonic gas jet target at IUCF. The emphasis has been on hydrogen jets that can be used as targets of similar 1016 atoms/cm2 thickness in high-luminosity experiments. A method of scanning jets with an ionizing 1 keV electron beam has been employed in order to study jet formation as a function of nozzle geometry and temperature. We summarize our results, obtained by scanning H2 jets from 23 different nozzles, most of them made from glass capillaries. The present setup of the jet target in the Cooler storage ring is described. (orig.)