The Nuclear Science Division at Lawrence Berkeley National Laboratory (LBNL) has been busy counting backgrounds for nearly 30 years, 600 feet underground in the hydropower plant adjacent to the Oroville Dam in Oroville, Calif. Such physics experiments as SNO, KamLAND and NEXT, as well as Sanford Lab?s Majorana (MJD) and Large Underground Xenon (LUX) experiments, benefitted from the data generated by the Oroville detector.
Keenan Thomas, an Assistant Specialist in the Department of Nuclear Engineering at UC Berkeley, said the detector is used to screen for radioactivity levels in materials that might be used in experiments.
?Even a small amount of radioactivity could spell disaster for sensitive experiments like LUX and MJD,? Thomas said.
Recently, the detector found a new home?4,850 feet below the surface at Sanford Lab?as a way to improve the detector?s screening sensitivity. ?I?m very pleased we were able to get the detector packed and moved to Sanford Lab,? said Kevin Lesko, Sanford Underground Research Facility Operations Head. ?This will put the United State?s most sensitive low background detector to where the action is for dark matter and double-beta decay.?
Thomas helped decommission the detector then drove it to Sanford Lab. The shielding structure?a 20-ton lead castle and inner copper shield?was shipped. It will be reassembled underground in the ?Berkeley Low Background Counting Facility,? near LUX. When completed, the detector will need to be tested for several weeks to ensure it is working properly in its new environment, Thomas said. It will be fully operational later this summer.