Operation of the accelerator

Fiscal Year 1994 was the first year of seven-day operation since ATLAS became a national user facility in 1985. ATLAS made the most of the opportunity this year by providing 5200 hours of beam on-target to the research program. A record number of 60 experiments were completed and the {open_quotes}facility reliability{close_quotes} remained near the 90% level. Seven-day operation was made possible with the addition to the staff of two operator positions providing single-operator coverage during the weekend period. The normally scheduled coverage was augmented by an on-call list of system experts who respond to emergencies with phone-in advice and return to the Laboratory when necessary. This staffing approach continues but we rearranged our staffing patterns so that we now have one cryogenics engineer working a shift pattern which includes 8-hour daily coverage during the weekend. ATLAS provided a beam mix to users consisting of 26 different isotopic species, 23% of which were for A>100 in FY 1994. Approximately 60% of the beam time was provided by the Positive Ion Injector, slightly less than the usage rate of FY 1993. Experiments using uranium or lead beams accounted for 16.4% of the total beam time. The ECR ion source and high-voltage platformmore » functioned well throughout the year. A new technique for solid material production in the source was developed which uses a sputtering process wherein the sample of material placed near the plasma chamber wall is biased negatively. Plasma ions are accelerated into the sample and material is sputtered from the surface into the plasma. This technique is now used routinely for many elements. Runs of calcium, germanium, nickel, lead, tellurium, and uranium were carried out with this technique.« less