Performance and Background Measurements of the CDMS II Tower I Detectors at the Stanford Underground Facility (original) (raw)

Deployment of the first CDMS II ZIP detectors at the stanford underground facility

Nuclear Physics B - Proceedings Supplements, 2002

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 (1OOg ea.) ZIPS, the run was the first demostration of multiple ZIPS operating simltaneously. Good discrimination between electron and nuclear recoil events of 99.8% was established, down to recoil energies of 10 keV. A measurement of the y, p, and neutron bsckgrounds was made.

Detector commissioning for the CDMS-II final run at the Soudan Underground Laboratory

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006

CDMS-II uses detectors known as Z-sensitive ionization phonons (ZIPs) to search for weakly interacting massive particles (WIMPs), a very promising candidate for the dark matter in the universe. The most recent data run utilized 12 ZIP detectors (six Ge and six Si) running for 1 2 year at the Soudan deep underground laboratory (780 m below surface), resulting in the current world's highest sensitivity to WIMP-nucleon coherent interaction [D.S. Akerib, et al., Phys. Rev. Lett. 93 (2004) 211301]. The CDMS-II experiment is approved to run 30 ZIPs until summer 2007 and its goal is to another order of magnitude increase in sensitivity to WIMPs. We present the detector preparation steps leading to the production of the CDMS-II detectors to be used in this final run.

Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007

The heat quenching factor Q ′ (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDEL-WEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q/Q ′ , where Q is the quenching factor of the ionization yield. To measure Q ′ , a precise EDELWEISS measurement of Q/Q ′ is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q ′ are discussed in detail. For recoil energies between 20 and 100 keV, the resulting heat quenching factor is Q ′ = 0.91 ± 0.03 ± 0.04, where the two errors are the contributions from the Q and Q/Q ′ measurements, respectively. The present compilation of Q values and evaluation of Q ′ represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for dark matter. PACS numbers: 29.40.Wk, 95.35.+d

Nuclear-recoil energy scale in CDMS II silicon dark-matter detectors

2018

The Cryogenic Dark Matter Search (CDMS II) experiment aims to detect dark matter particles that elastically scatter from nuclei in semiconductor detectors. The resulting nuclear-recoil energy depositions are detected by ionization and phonon sensors. Neutrons produce a similar spectrum of low-energy nuclear recoils in such detectors, while most other backgrounds produce electron recoils. The absolute energy scale for nuclear recoils is necessary to interpret results correctly. The energy scale can be determined in CDMS II silicon detectors using neutrons incident from a broad-spectrum Cf-252 source, taking advantage of a prominent resonance in the neutron elastic scattering cross section of silicon at a recoil (neutron) energy near 20 (182) keV. Results indicate that the phonon collection efficiency for nuclear recoils is 4.8(+0.7,−0.9)% lower than for electron recoils of the same energy. Comparisons of the ionization signals for nuclear recoils to those measured previously by other groups at higher electric fields indicate that the ionization collection efficiency for CDMS II silicon detectors operated at ∼4 V/cm is consistent with 100% for nuclear recoils below 20 keV and gradually decreases for larger energies to ∼75% at 100 keV. The impact of these measurements on previously published CDMS II silicon results is small.

Radioactive beam experiments with large gamma-ray detector arrays

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2003

High-resolution c-ray spectroscopy is one of the most powerful and versatile experimental techniques in low-energy nuclear physics research. With the continuing development of hyper-pure germanium (HPGe) detector technology, including multi-crystal detectors, contact segmentation, and digital signal processing techniques, large c-ray detector arrays will continue to play a major role in the experimental programs at existing and future radioactive ion beam facilities. This paper provides an overview of recent progress in, and future plans for, the development of large c-ray spectrometers at such facilities, including the recent commissioning of the 8p spectrometer at ISAC-I and the proposed TRIUMF-ISAC gamma-ray escape suppressed spectrometer array for the ISAC-II facility.

Cosmic-ray neutron spectrometry by solid state detectors

Radiation Measurements, 2003

Extensive data have been gathered since the early 1990s on the response of di erent detectors based on the registration of neutron-induced ÿssion in bismuth, gold, tantalum by the spark replica counter and the thin ÿlm breakdown counter. These detectors make it possible to exploit the excellent characteristics of the ÿssion reactions in bismuth, gold and tantalum for the measurements of high-energy neutrons. Most of the investigations have been carried out at the quasi-monoenergetic neutron beam facility at The Svedberg Laboratory-TSL of the Uppsala University in cooperation with the Khlopin Radium Institute (KRI). The responses of di erent ÿssion detectors in the intermediate range of neutron energy (35-180 MeV) have been evaluated: a region where the predictive power of available nuclear reaction models and codes is not reliable yet. For neutron energy greater than 200 MeV, the ÿssion-detector responses have been derived from the data of the proton ÿssion cross-sections. Finally, by using the ratio of the responses of these detectors, a simple and accurate way to evaluate the spectrum hardness can be obtained, thus providing a tool to obtain spectral information needed for neutron dosimetry without the need to know the entire spectrum. The experimentally measured spectra obtained to-date have di erent shapes and they are also di erent from those calculated. In this paper, a new approach will be reported to analyse the existing spectra by using response ratios of di erent detectors. Preliminary data have been already obtained for the high-energy neutron spectrum from the CERN concrete facility.