31 research outputs found
In-situ characterization of the Hamamatsu R5912-HQE photomultiplier tubes used in the DEAP-3600 experiment
The Hamamatsu R5912-HQE photomultiplier-tube (PMT) is a novel high-quantum
efficiency PMT. It is currently used in the DEAP-3600 dark matter detector and
is of significant interest for future dark matter and neutrino experiments
where high signal yields are needed.
We report on the methods developed for in-situ characterization and
monitoring of DEAP's 255 R5912-HQE PMTs. This includes a detailed discussion of
typical measured single-photoelectron charge distributions, correlated noise
(afterpulsing), dark noise, double, and late pulsing characteristics. The
characterization is performed during the detector commissioning phase using
laser light injected through a light diffusing sphere and during normal
detector operation using LED light injected through optical fibres
Electromagnetic backgrounds and potassium-42 activity in the DEAP-3600 dark matter detector
See full article for abstrac
Recommended from our members
Design and construction of the DEAP-3600 dark matter detector
The Dark matter Experiment using Argon Pulse-shape discrimination (DEAP) has been designed for a direct detection search for particle dark matter using a single-phase liquid argon target. The projected cross section sensitivity for DEAP-3600 to the spin-independent scattering of Weakly Interacting Massive Particles (WIMPs) on nucleons is 10 cm for a 100 GeV/c WIMP mass with a fiducial exposure of 3 tonne-years. This paper describes the physical properties and construction of the DEAP-3600 detector. −46 2
Search for dark matter with a 231-day exposure of liquid argon using DEAP-3600 at SNOLAB
DEAP-3600 is a single-phase liquid argon (LAr) direct-detection dark matter experiment, operating 2 km underground at SNOLAB (Sudbury, Canada). The detector consists of 3279 kg of LAr contained in a spherical acrylic vessel. This paper reports on the analysis of a 758  tonne⋅day exposure taken over a period of 231 live-days during the first year of operation. No candidate signal events are observed in the WIMP-search region of interest, which results in the leading limit on the WIMP-nucleon spin-independent cross section on a LAr target of 3.9×10−45  cm2 (1.5×10−44  cm2) for a 100  GeV/c2 (1  TeV/c2) WIMP mass at 90% C.L. In addition to a detailed background model, this analysis demonstrates the best pulse-shape discrimination in LAr at threshold, employs a Bayesian photoelectron-counting technique to improve the energy resolution and discrimination efficiency, and utilizes two position reconstruction algorithms based on the charge and photon detection time distributions observed in each photomultiplier tube
Design and construction of the DEAP-3600 dark matter detector
The Dark matter Experiment using Argon Pulse-shape discrimination (DEAP) has been designed for a direct detection search for particle dark matter using a single-phase liquid argon target. The projected cross section sensitivity for DEAP-3600 to the spin-independent scattering of Weakly Interacting Massive Particles (WIMPs) on nucleons is 10−46cm2 for a 100 GeV/c2 WIMP mass with a fiducial exposure of 3 tonne-years. This paper describes the physical properties and construction of the DEAP-3600 detector
First results from the DEAP-3600 dark matter search with argon at SNOLAB
This paper reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fidicial exposure of 9.87 tonne days) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage <1.2X107 (90% C.L.) between 15 and 31 keVee. No candidate signal events
are observed, which results in the leading limit on WIMP-nucleon spin-independent cross section on argon, <1.21044 cm2 for a 100 GeV/c2 WIMP mass (90% C.L.)
The liquid-argon scintillation pulseshape in DEAP-3600
DEAP-3600 is a liquid-argon scintillation detector looking for dark matter. Scintillation events in the liquid argon (LAr) are registered by 255 photomultiplier tubes (PMTs), and pulseshape discrimination (PSD) is used to suppress electromagnetic background events. The excellent PSD performance of LAr makes it a viable target for dark matter searches, and the LAr scintillation pulseshape discussed here is the basis of PSD. The observed pulseshape is a combination of LAr scintillation physics with detector effects. We present a model for the pulseshape of electromagnetic background events in the energy region of interest for dark matter searches. The model is composed of (a) LAr scintillation physics, including the so-called intermediate component, (b) the time response of the TPB wavelength shifter, including delayed TPB emission at
O(ms) time-scales, and c) PMT response. TPB is the wavelength shifter of choice in most LAr detectors. We find that approximately 10% of the intensity of the wavelength-shifted light is in a long-lived state of TPB. This causes light from an event to spill into subsequent events to an extent not usually accounted for in the design and data analysis of LAr-based detectors
Constraints on dark matter-nucleon effective couplings in the presence of kinematically distinct halo substructures using the DEAP-3600 detector
DEAP-3600 is a single-phase liquid argon detector aiming to directly detect
Weakly Interacting Massive Particles (WIMPs), located at SNOLAB (Sudbury,
Canada). After analyzing data taken during the first year of operation, a null
result was used to place an upper bound on the WIMP-nucleon spin-independent,
isoscalar cross section. This study reinterprets this result within a
Non-Relativistic Effective Field Theory framework, and further examines how
various possible substructures in the local dark matter halo may affect these
constraints. Such substructures are hinted at by kinematic structures in the
local stellar distribution observed by the Gaia satellite and other recent
astronomical surveys. These include the Gaia Sausage (or Enceladus), as well as
a number of distinct streams identified in recent studies. Limits are presented
for the coupling strength of the effective contact interaction operators
, , , , and
, considering isoscalar, isovector, and xenonphobic
scenarios, as well as the specific operators corresponding to millicharge,
magnetic dipole, electric dipole, and anapole interactions. The effects of halo
substructures on each of these operators are explored as well, showing that the
and operators are particularly sensitive to the
velocity distribution, even at dark matter masses above 100 GeV/