Nuclear-recoil energy scale in CDMS II silicon dark-matter detectors Agnese, R.; Anderson, A. J.; Aramaki, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2018, Letnik:
905, Številka:
C
Journal Article
Recenzirano
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 252Cf 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.
We report the result of a blinded search for Weakly Interacting Massive Particles (WIMPs) using the full SuperCDMS Soudan dataset. With an exposure of 1690 kg days, a single event was observed after ...unblinding, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP-nucleon cross section of 1.4x10^-44 (1.0x10^-44) cm^2 at 46 GeV/c^2 . These results set the strongest limits for WIMP-germanium-nucleus interactions for masses >12 GeV/c^2.
Nuclear-recoil energy scale in CDMS II silicon dark-matter detectors Agnese, R.; Anderson, A. J.; Aramaki, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2018, Letnik:
905, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The Cryogenic Dark Matter Search (CDMS II) experiment aims to detect dark matter particles that elastically scatter from nuclei in semiconductor detectors. In this paper, 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 252 Cf 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 . 9 + 0 . 7 % 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. Finally, the impact of these measurements on previously published CDMS II silicon results is small.
Nuclear-recoil energy scale in CDMS II silicon dark-matter detectors Agnese, R.; Anderson, A. J.; Aramaki, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2018, Letnik:
905, Številka:
C
Journal Article
Recenzirano
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 $^{252}$Cf 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 $\sim$4 V/cm is consistent with 100% for nuclear recoils below 20 keV and gradually decreases for larger energies to $\sim$75% at 100 keV. The impact of these measurements on previously published CDMS II silicon results is small.
Although the events and aftermath of Sep 11 have changed the world forever, just how and to what extent remains more elusive. Well-publicized events compel social workers to rethink their strategies ...for providing adequate outreach, prevention and intervention to individuals and communities regarding mental health.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Future direct searches for low-mass dark matter particles with germanium detectors, such as SuperCDMS SNOLAB, are expected to be limited by backgrounds from radioactive isotopes activated by ...cosmogenic radiation inside the germanium. There are limited experimental data available to constrain production rates and a large spread of theoretical predictions. We examine the calculation of expected production rates, and analyze data from the second run of the CDMS low ionization threshold experiment (CDMSlite) to estimate the rates for several isotopes. We model the measured CDMSlite spectrum and fit for contributions from tritium and other isotopes. Using the knowledge of the detector history, these results are converted to cosmogenic production rates at sea level. The production rates in atoms/(kg·day) are 74±9 for 3H, 1.5±0.7 for 55Fe, 17±5 for 65Zn, and 30±18 for 68Ge.
SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass particles (with masses ≤ 10 GeV/c^2) that may constitute dark matter by using cryogenic detectors of two ...types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~1×10^-43 cm^2 for a dark matter particle mass of 1 GeV/c^2, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark matter. A detailed calibration of the detector response to low-energy recoils will be needed to optimize running conditions of the HV detectors and to interpret their data for dark matter searches. Low-activity shielding, and the depth of SNOLAB, will reduce most backgrounds, but cosmogenically produced H-3 and naturally occurring Si-32 will be present in the detectors at some level. Even if these backgrounds are 10 times higher than expected, the science reach of the HV detectors would be over 3 orders of magnitude beyond current results for a dark matter mass of 1 GeV/c^2. The iZIP detectors are relatively insensitive to variations in detector response and backgrounds, and will provide better sensitivity for dark matter particles with masses ≳5 GeV/c^2. The mix of detector types (HV and iZIP), and targets (germanium and silicon), planned for the experiment, as well as flexibility in how the detectors are operated, will allow us to maximize the low-mass reach, and understand the backgrounds that the experiment will encounter. Upgrades to the experiment, perhaps with a variety of ultra-low-background cryogenic detectors, will extend dark matter sensitivity down to the “neutrino floor,” where coherent scatters of solar neutrinos become a limiting background.
Future direct searches for low-mass dark matter particles with germanium detectors, such as SuperCDMS SNOLAB, are expected to be limited by backgrounds from radioactive isotopes activated by ...cosmogenic radiation inside the germanium. There are limited experimental data available to constrain production rates and a large spread of theoretical predictions. We examine the calculation of expected production rates, and analyze data from the second run of the CDMS low ionization threshold experiment (CDMSlite) to estimate the rates for several isotopes. We model the measured CDMSlite spectrum and fit for contributions from tritium and other isotopes. Using the knowledge of the detector history, these results are converted to cosmogenic production rates at sea level. The production rates in atoms/(kg$\cdot$day) are 74$\pm$9 for $^3$H, 1.5$\pm$0.7 for $^{55}$Fe, 17$\pm$5 for $^{65}$Zn, and 30$\pm$18 for $^{68}$Ge.
CDF run IIb silicon detector: the innermost layer Merkel, P.; Azzi, P.; Bacchetta, N. ...
IEEE transactions on nuclear science,
2004-Oct., 2004-10-00, 20041001, Letnik:
51, Številka:
5
Journal Article
Recenzirano
Odprti dostop
The innermost layer (L00) of the Run IIa silicon detector of CDF was planned to be replaced for the high luminosity Tevatron upgrade of Run IIb. This new silicon layer (L0) is designed to be a ...radiation tolerant replacement for the otherwise very similar L00 from Run IIa. The data are read out via long, fine-pitch, low-mass cables allowing the hybrids with the chips to sit at higher z(/spl sim/70 cm), outside of the tracking volume. The design and first results from the prototyping phase are presented. Special focus is placed on the amount and the structure of induced noise as well as signal-to-noise values.
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