The CDMS II experiment deployed the first set of ZIP (Z-dependent Ionization and Phonon) detectors at the Stanford Underground Facility (SUF) shallow depth site in the spring of 2000. With a payload consisting of 3 Ge (250g ea.) and 3 Si (100g ea.) ZIPs, the run was the first demostration of multiple ZIPs operating simultaneously. Good discrimination between electron and nuclear recoil events of 99.8% was established, down to recoil energies of 10 keV. A measurement of the γ, β, and neutron backgrounds was made.
Bibliographical noteFunding Information:
measured in previous runs, with no muon anti-coincident events seen in the nuclear recoil bands of any detector. With the latest set of ZIP detectors well characterized at the shallow depth SUF facility, the experiment will resume data taking as soon as the move to the Soudan deep site is completed in early 2002. This work is supported by the Center for Particle Astrophysics, an NSF Science and Technology Center operated by the University of California, Berkeley, under Cooperative Agreement No. AST-91-20005, by the National Science Fo undation under Grant No. PHY-9722414, and by the Department of Energy under contracts DEAC03-76SF00098, DEFG03-90ER40569, and DEFG03-91ER40618.