76 research outputs found
Superheated Droplet Detectors as CDM Detectors: The SIMPLE Experiment
Superheated Droplet Detectors (SDDs) are becoming commonplace in neutron
personnel dosimetry. Their total insensitivity to minimum ionizing radiation
(while responsive to nuclear recoils of energies ~ few keV), together with
their low cost, ease of production, and operation at room temperature and 1 atm
makes them ideal for Cold Dark Matter (CDM) searches. SDD's are optimal for the
exploration of the spin-dependent neutralino coupling due to their high
fluorine content. The status of SIMPLE (Superheated Instrument for Massive
ParticLe Experiments) is presented. Under realistic background considerations,
we expect an improvement in the present Cold Dark Matter sensitivity of 2-3
orders of magnitude after ~1 kg-y of data acquisition.Comment: 6 pages, including 4 figures. To appear in the Proceedings of the
Intl. Workshop on the Identification of Dark Matter (Sheffield, Sept. 96
First Characterization of the Ultra-Shielded Chamber in the Low-noise Underground Laboratory (LSBB) of Rustrel Pays d'Apt
In compliance with international agreements on nuclear weapons limitation,
the French ground-based nuclear arsenal has been decommissioned in its
totality. One of its former underground missile control centers, located in
Rustrel, 60 km east of Avignon (Provence) has been converted into the
``Laboratoire Souterrain \`a Bas Bruit de Rustrel-Pays d'Apt'' (LSBB). The
deepest experimental hall (500 m of calcite rock overburden) includes a 100
m area of sturdy flooring suspended by and resting on shock absorbers,
entirely enclosed in a 28 m-long, 8 m-diameter, 1 cm-thick steel Faraday cage.
This results in an unparalleled combination of shielding against cosmic rays,
acoustic, seismic and electromagnetic noise, which can be exploited for rare
event searches using ultra low-temperature and superconducting detectors. The
first characterization measurements in this unique civilian site are reported.
For more info see http://home.cern.ch/collar/RUSTREL/rustrel.htmlComment: Homepage and quoted hyperlinks have been updated: see
http://home.cern.ch/collar/RUSTREL/rustrel.htm
A CF3I-based SDD Prototype for Spin-independent Dark Matter Searches
The application of Superheated Droplet Detectors (SDDs) to dark matter
searches has so far been confined to the light nuclei refrigerants C2ClF5 and
C4F10 (SIMPLE and PICASSO, respectively), with a principle sensitivity to
spin-dependent interactions. Given the competitive results of these devices, as
a result of their intrinsic insensitivity to backgrounds, we have developed a
prototype trifluoroiodomethane (CF3I)-loaded SDD with increased sensitivity to
spin-independent interactions as well. A low (0.102 kgd) exposure test
operation of two high concentration, 1 liter devices is described, and the
results compared with leading experiments in both spin-dependent and
-independent sectors. Although competitive in both sectors when the difference
in exposures is accounted for, a problem with fracturing of the detector gel
must be addressed before significantly larger exposures can be envisioned.Comment: revised and updated; accepted Astrop. Phy
Beta Irradiation of a Geometrically Metastable Superconducting Strip Detector with a Magnetic Flux Penetration Read-Out
Geometrical metastability, observed in superconducting type I tin flat
strips, has been previously proposed as a principle for particle detection. The
energy deposition of an incoming beta-particle induces the rupture of the
metastability and consequently the penetration of multiquantum flux tubes into
a superconducting tin strip. We present here the first absorption spectra from
two beta sources, which demonstrate the linearity and energy-resolution of
these detectors (presented at the 6th International Workshop on Low Temperature
Detectors for Dark Matter and Neutrinos (LTD-6), Interlaken, Switzerland, Sept.
1995)Comment: Compressed PostScript (filename.ps.Z), 8 pages, 2 figure
WIMP searches with superheated droplet detectors: Status and Prospects
SIMPLE (Superheated Instrument for Massive ParticLE searches) employs
superheated droplet detectors (SDDs) to search for Weakly Interacting Massive
Particle (WIMP) dark matter. As a result of the intrinsic SDD insensitivity to
minimum ionizing particles and high fluorine content of target liquids,
competitive WIMP limits were already obtained at the early prototype stage. We
comment here on the expected immediate increase in sensitivity of the program
and on future plans to exploit this promising technnique.Comment: 6 pages LaTeX, incl. 2 figures. Presented at the 3rd Intl. Workshop
for the Identification of Dark Matter (IDM2000), York, Sept. 200
First Dark Matter Limits from a Large-Mass, Low-Background Superheated Droplet Detector
We report on the fabrication aspects and calibration of the first large
active mass ( g) modules of SIMPLE, a search for particle dark matter
using Superheated Droplet Detectors (SDDs). While still limited by the
statistical uncertainty of the small data sample on hand, the first weeks of
operation in the new underground laboratory of Rustrel-Pays d'Apt already
provide a sensitivity to axially-coupled Weakly Interacting Massive Particles
(WIMPs) competitive with leading experiments, confirming SDDs as a convenient,
low-cost alternative for WIMP detection.Comment: Final version, Phys. Rev. Lett. (in press
S-35 Beta Irradiation of a Tin Strip in a State of Superconducting Geometrical Metastability
We report the first energy loss spectrum obtained with a geometrically
metastable type I superconducting tin strip irradiated by the beta-emission of
S-35. (Nucl. Instr. Meth. A, in press)Comment: Compressed PostScript (filename.ps.Z), 9 pages, 2 figure
Prospects for SIMPLE 2000: A large-mass, low-background Superheated Droplet Detector for WIMP searches
SIMPLE 2000 (Superheated Instrument for Massive ParticLE searches) will
consist of an array of eight to sixteen large active mass ( g)
Superheated Droplet Detectors(SDDs) to be installed in the new underground
laboratory of Rustrel-Pays d'Apt. Several factors make of SDDs an attractive
approach for the detection of Weakly Interacting Massive Particles (WIMPs),
namely their intrinsic insensitivity to minimum ionizing particles, high
fluorine content, low cost and operation near ambient pressure and temperature.
We comment here on the fabrication, calibration and already-competitive first
limits from SIMPLE prototype SDDs, as well as on the expected immediate
increase in sensitivity of the program, which aims at an exposure of 25
kg-day during the year 2000. The ability of modest-mass fluorine-rich detectors
to explore regions of neutralino parameter space beyond the reach of the most
ambitious cryogenic projects is pointed out.Comment: 19 pages, 10 figures included. New Journal of Physics, in pres
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