DUSEL Low-Background Counting (to get the program started) Dongming Mei 1, Kevin Lesko 2,Christina Keller 1, Yongchen Sun 1, Zhongbao Yin 1, Keenan Thomas 1, Robert McTaggart 3, Barbara Szczerbinska 4, Drew Alton 5, William Roggenthen 6, Yuen-Dat Chan 2, Al Smith 2, Gersende Prior 2 1 : The University of South Dakota 2 : Lawrence Berkeley National Laboratory 3 :South Dakota State University 4 : Dakota State University 5 : Augustana College 6 : South Dakota School Mines & Technology

Phased approach to a full scale facility (The funding listed here are possibilities) Phase I (Meet requirements for the Early implementation experiments) –DOE EPSCoR proposal: , $0.5 M Status: Pending –Two gamma counting stations Phase II (Meet requirements for double-beta decay and other large scale experiments) –DOE EPSCoR proposal: , $0.5 M Status: in preparation Alpha/beta counting –NSF EPSCoR proposal: , ~$2 M Status: in preparation More gamma-counting stations Larger alpha/beta counting facility NAA technique ICPMS Laser isotope separation

Phase I Facility (to get it started) Underground at 4850-ft level:

Sensitivity plot at 4850-ft level 232 Th< g/g, 238 U< g/g Sufficient for most external materials, but not for very low contamination.

First stage design

Phase I facility for the early implementation experiments Gamma-ray counting –Two counting stations for PMTs 1 – 100 ppb is easy to achieve –Counting for other materials 1 to 100 ppt 0.1 ppt for acrylic counting: NAA –Coincidence counting is also possible Cumulate experience –Operate an user facility underground –Build a large scale facility in the future

Phase II for other experiments Copper counting –NAA to 0.1 μBq/kg for 232 Th –ICPMS to 1 to 3 μBq/kg for 238 U Lead counting –1-100 ppt Poly counting –1 – 100 ppt Germanium crystals –Laser isotope separation to < g/g

Phase III for space program and national security DOE and NSF EPSCoR program $3 M –Scale up the facility –Add chemical clean projects –Increase the counting capability –Make a multidisciplinary counting facility