The PICASSO dark matter search experiment operated an array of 32 superheated droplet detectors containing 3.0 kg of C4F10 and collected an exposure of 231.4 kgd at SNOLAB between March 2012 and ...January 2014. We report on the final results of this experiment which includes for the first time the complete data set and improved analysis techniques including acoustic localization to allow fiducialization and removal of higher activity regions within the detectors. No signal consistent with dark matter was observed. We set limits for spin-dependent interactions on protons of σpSD = 1.32 × 10−2 pb (90% C.L.) at a WIMP mass of 20 GeV/c2. In the spin-independent sector we exclude cross sections larger than σpSI = 4.86 × 10−5 pb (90% C.L.) in the region around 7 GeV/c2. The pioneering efforts of the PICASSO experiment have paved the way forward for a next generation detector incorporating much of this technology and experience into larger mass bubble chambers.
Recent results from the PICASSO dark matter search experiment at SNOLAB are reported. These results were obtained using a subset of 10 detectors with a total target mass of 0.72 kg of 19F and an ...exposure of 114 kgd. The low backgrounds in PICASSO allow recoil energy thresholds as low as 1.7 keV to be obtained which results in an increased sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below 10 GeV/c2. No dark matter signal was found. Best exclusion limits in the spin dependent sector were obtained for WIMP masses of 20 GeV/c2 with a cross section on protons of σpSD=0.032 pb (90% C.L.). In the spin independent sector close to the low mass region of 7 GeV/c2 favoured by CoGeNT and DAMA/LIBRA, cross sections larger than σpSI=1.41×10−4 pb (90% C.L.) are excluded.
Dark matter search with PICASSO Zacek, V; Archambault, S; Behnke, E ...
Journal of physics. Conference series,
01/2012, Letnik:
375, Številka:
1
Journal Article
Recenzirano
Odprti dostop
PICASSO at SNOLAB searches primarily for spin-dependent WIMP interactions on 19F using the superheated droplet technique. This technique is based on the bubble chamber principle, where phase ...transitions in superheated liquid droplets can be triggered by WIMP induced nuclear recoils. The physics of the detection process allows a highly efficient suppression of backgrounds from cosmic muons, γ- and β-rays. We will discuss qualitatively recent progress in PICASSO and its sensitivity reach for spin-dependent and spin-independent WIMP searches.
We have remotely mapped optical scattering and absorption in glacial ice at the South Pole for wavelengths between 313 and 560 nm and depths between 1100 and 2350 m. We used pulsed and continuous ...light sources embedded with the AMANDA neutrino telescope, an array of more than six hundred photomultiplier tubes buried deep in the ice. At depths greater than 1300 m, both the scattering coefficient and absorptivity follow vertical variations in concentration of dust impurities, which are seen in ice cores from other Antarctic sites and which track climatological changes. The scattering coefficient varies by a factor of seven, and absorptivity (for wavelengths less than ∼450 nm) varies by a factor of three in the depth range between 1300 and 2300 m, where four dust peaks due to stadials in the late Pleistocene have been identified. In our absorption data, we also identify a broad peak due to the Last Glacial Maximum around 1300 m. In the scattering data, this peak is partially masked by scattering on residual air bubbles, whose contribution dominates the scattering coefficient in shallower ice but vanishes at ∼1350 m where all bubbles have converted to nonscattering air hydrates. The wavelength dependence of scattering by dust is described by a power law with exponent −0.90 ± 0.03, independent of depth. The wavelength dependence of absorptivity in the studied wavelength range is described by the sum of two components: a power law due to absorption by dust, with exponent −1.08 ± 0.01 and a normalization proportional to dust concentration that varies with depth; and a rising exponential due to intrinsic ice absorption which dominates at wavelengths greater than ∼500 nm.
Searching for Dark Matter with PICASSO Archambault, S.; Behnke, E.; Besnier, M. ...
Physics procedia,
2015, 2015-00-00, Letnik:
61
Journal Article, Conference Proceeding
Odprti dostop
The Project In CAnada to Search for Supersymmetric Objects (PICASSO) at SNOLAB searches for Weakly Interacting Massive Particle (WIMP) interactions with 19F. It is particularly sensitive to ...spin-dependent particle interactions. It uses a droplet technique, based on the principle of a bubble chamber, in which phase transitions in superheated liquids can be triggered by WIMP induced nuclear recoils. The detection process allows a highly efficient suppression of backgrounds from cosmic muons, γ rays and electrons. Recent results and progress are presented and future plans to scale this technique to large masses with the PICO collaboration are briefly discussed.
The I ceC ube prototype string in A manda Ahrens, J.; Bai, X.; Barwick, S.W. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2006, Letnik:
556, Številka:
1
Journal Article
Recenzirano
The Antarctic Muon And Neutrino Detector Array (A
manda) is a high-energy neutrino telescope. It is a lattice of optical modules (OM) installed in the clear ice below the South Pole Station. Each OM ...contains a photomultiplier tube (PMT) that detects photons of Cherenkov light generated in the ice by muons and electrons. I
ceC
ube is a cubic-kilometer-sized expansion of A
manda currently being built at the South Pole. In I
ceC
ube the PMT signals are digitized already in the optical modules and transmitted to the surface. A prototype string of 41 OMs equipped with this new all-digital technology was deployed in the A
manda array in the year 2000. In this paper we describe the technology and demonstrate that this string serves as a proof of concept for the I
ceC
ube array. Our investigations show that the OM timing accuracy is 5
ns. Atmospheric muons are detected in excellent agreement with expectations with respect to both angular distribution and absolute rate.
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