Helium and hydrogen measurements on pure materials irradiated in SINQ Target 4

Several irradiations have been performed in the Swiss Spallation Neutron Source (SINQ) to establish a materials database for mixed proton and neutron fluxes for future spallation neutron and other accelerator sources. Pure metal dosimetry materials from the second irradiation (STIP-II) have been analyzed for their total helium and hydrogen contents and their release characteristics with temperature (TDS). Total helium results are similar to those observed earlier from the first irradiation experiment (STIP-I), with concentrations ranging from ∼500 to ∼1000 appm. Hydrogen contents varied over a larger range from ∼100 to ∼60 000. 3He/4He ratios were generally consistent with expectations, except for Ti, Nb, and Ta which showed lower values due to 3He from decay of irradiation-generated tritium. Some differences were observed in the hydrogen TDS data for the control and irradiated materials, including some evidence for additional lower-temperature release and for multiple release peaks. Additionally, differences were noted in the releases for irradiated material that been cleaned versus material that had no cleaning.