RA2. Accelerator System Status
ORIC Operations and Development (B. A. Tatum)
Due to the July 2008 Operational Emergency, ORIC remained shut down for most of the January--to-July period as various corrective actions were implemented. As part of the phased restart of the facility, we received permission in late winter to deliver light ion beam to non-uranium targets at the High Power Target Laboratory (HPTL). A nominal 54-MeV proton beam was subsequently delivered to a niobium silicide target at the HPTL for the production of 25Al and 26Al beams. Details of this beam development activity are provided in this Newsletter by Dan Stracener on RIB Development.
Permission to resume full facility operations including proton beam on uranium carbide targets was granted in late June following the completion of all necessary corrective actions related to the Operational Emergency. As mentioned by Jim Beene in his HRIBF Update and Near-Term Schedule, starting ORIC after many months of shutdown is difficult. We have been systematically restoring the machine to an operational status and have had a few setbacks along the way. Examples of difficulties include mechanical drive system vacuum seals which become rigid when not exercised, and current power supplies that have not operated at high current levels for an extended period. Nevertheless, we are anticipating a resumption of routine operation for the proton- and neutron-rich experimental programs during the remainder of the summer and into the fall.
We have been awarded $2.5M in American Recovery and Reinvestment Act (ARRA/stimulus) funds to be utilized over the next four years. One of the major uses of these funds will be the replacement of the 1938-vintage ORIC main magnetic field motor-generator set which provides up to 5000Adc at 360V to the main magnet coils. The MG set will be replaced with a dc power supply. The present plan is to retain the MG set as a backup. Improvements will also be made to the ORIC extraction and rf systems, the 1960's vintage diffusion pumps will be replaced, high-current beam stops will be installed, HVAC stack monitors will be implemented, and the IRIS1 target handling system electronics will be upgraded. These improvements combined with base capital equipment and Accelerator Improvement Project funds will substantially modernize ORIC and lead to higher reliability.
RIB Injector Operations and Development (P.E. Mueller)
During the period from January 1, 2009 to June 30, 2009, the 25 MV Tandem Electrostatic Accelerator delivered beams of
510 kpps [ 6.88 MV 2+ terminal gas stripped ] 18-MeV 26gAl and 1.5 Mpps [ 9.9 MV 3+ terminal gas stripped ] 36-MeV 26gAl to Beam Line 41, 16 Mpps [ 21.47 MV 5+ terminal gas stripped ] 117-MeV 26gAl to the ORRUBArray in Beam Line 21, 630 kpps [ 6.12 MV 1+ terminal gas stripped ] 8-MeV 7 Be to the Beam Line 22 tribology deposition chamber, 70 kpps [ 10.04 MV 2+ / 4+ terminal gas & foil / post foil stripped ] 23-MeV 100% 7Be to Beam Line 41, 10 Mpps [ 24.65 MV 4+ / 4+ terminal gas & foil / post foil stripped ] 107-MeV 99% 10Be to the ORRUBArray in Beam Line 21, and 27 Mpps [ 12.25 MV 2+ / 4+ terminal gas & foil / post foil stripped ] 29-MeV 99% 10Be to Beam Line 41.
Other beams of 26gAl from 13 to 40 MeV were also delivered to Beam Line 41.
All of these beams were produced with the multisample cesium sputter negative ion source using pressed powder copper targets loaded with 26gAl2O3, 7BeO, or 10BeO as appropriate.
Tandem Operations and Development (M. Meigs)
The Tandem Accelerator was operated for more than 1900 hours since the last report. The machine ran at terminal potentials of 1.34 to 24.65 MV. The multi-sample ion source was used on IRIS1 to provide the radioactive beams of 7,10Be and 26Al. In addition, the SNICS was used to provide the stable beams 1H, 7Li, 17,18O, 27Al, 54Fe, 58Ni, 76Ge, 107Ag, 115In, and 120Sn. About 64 hours were spent conditioning, most of which was necessary after a spark at 24.65 MV caused deconditioning. Three tank openings were completed during this period; the first to repair the foil stripper which had stuck in place, the second to do regular maintenance and to repair the low intensity diagnostics in preparation for radioactive beams, and the last to repair the gas stripper. Quite a few hours during this period were spent on SNICS development, leading to a greater understanding of the operation of the source.