RA2. Accelerator System Status
ORIC Operations and Development (B. A. Tatum)
ORIC's reliable operation during the reporting period was instrumental to the completion of the most successful operations year in HRIBF history. From July through mid October, ORIC provided 54 MeV protons to the High Power Target Laboratory (HPTL) for development of aluminum beams from SiC targets, and to the Injector for Radioactive Ion Species (IRIS1) for production of neutron-rich beams for the RIB experimental program. ORIC was shut down for much of the first quarter of FY2008 for budgetary reasons, machine maintenance, and the transition to deuteron beams that will be used for proton-rich RIB production in the second quarter. ORIC has continued to experience some chronic problems with the rf trimmer servos, a few older power supplies, and small vacuum leaks. Once the FY2008 budget is known, we plan to allocate capital equipment and AIP funds to order replacements for the 20" cryopump used on the south end of ORIC, the harmonic coil power supplies, the lower channel inside coil power supply, and to make additional rf improvements including procurement of a spare rf power amplifier tube.
RIB Injector Operations and Development (P.E. Mueller)
During the period of 1 July 2007 to 31 December 2007, the 25-MV Tandem Electrostatic Accelerator delivered radioactive-ion beams of
10 Mpps [23.3 MV 16+ terminal foil stripped] 396 MeV 80% 132Te to the general purpose endstation in Beam Line 21, 40 kpps [22.7 MV 15+/27+ terminal foil / high energy foil stripped] 545 MeV 95% 132Sn, 62 kpps [22.7 MV 15+/26+ terminal foil / high energy foil stripped] 530 MeV 95% 132Sn, and 65 kpps [22.4 MV 14+/26+ terminal foil / high energy foil stripped] 515 MeV 95% 132Sn to the time-of-flight endstation in Beam Line 23, and 40 kpps [16.2 MV 11+ terminal foil stripped] 193 MeV 42% 84Se, 1 Mpps [15.0 MV 11+ terminal foil stripped] 179 MeV 99% 78Ge, 200 kpps [15.4 MV 11+ terminal foil stripped] 184 MeV 98% 80Ge, and 20 kpps [22.7 MV 17+ terminal foil stripped] 408 MeV 90% 136Te, to the Recoil Mass Spectrometer in Beam Line 14.
These beams were produced via proton induced fission of 238U by bombarding a pressed powder uranium carbide target coupled to an Electron Beam Plasma (positive) Ion Source (EBPIS) with 7.5 - 18 uA of 50 MeV 1H. Additionally, the high purity germanium and tin beams were produced by passing a positive germanium or tin sulfide beam through the recirculating cesium jet charge exchange cell and selecting the negative germanium or tin beam resulting from molecular breakup.
Tandem Operations and Development (M. Meigs)
The Tandem Accelerator was operated for about 2450 hours since the last report. The machine ran at terminal potentials of 3.10 to 23.4 MV and the stable beams 1H, 7Li, 15N, 17O, 19F, 54Fe, 58Ni, 76Ge, 76,78,80,82Se, 90Zr, 92Mo, 107Ag, 118,124Sn, and 130Te were accelerated. Radioactive beams of 78,80Ge, 84Se, 126,132Sn, and 132,136Te accounted for more than 730 hours of beam on target. Conditioning was done for only 26 hours to return the machine to operation after having the terminal up to atmosphere to change foils. Only one tank opening was required during this period for scheduled maintenance.