We report first results from the ZEPLIN I dark matter detector, based on measurement of scintillation pulse shapes in a liquid xenon target of 3.2
kg fiducial mass. Neutron calibration shows nuclear ...recoil pulses to have a time constant
≅
0.5 that of gamma and beta background events. The detector is located in the 2800
mwe depth UK Boulby Mine, and is surrounded by a liquid scintillator Compton veto and passive lead shielding. Three runs totaling 293
kg
d fiducial exposure yielded data consistent with a single population of background pulses, with no significant low energy population of shorter pulses. From the 90% confidence limit on the latter a limit is derived on the spin-independent WIMP-nucleon cross-section versus particle mass with a minimum at 1.1
×
10
−6
pb.
The development and clinical testing of an herbal lice removal shampoo, containing a standardized extract of paw paw, thymol, and tea tree oil, are described. All of these ingredients were selected ...for their ability to deplete adenosine triphosphate (ATP) levels and, thus, prevent ATP-dependent pesticide resistance. Optimum concentrations of the ingredients, treatment times, and dosing schedules were established through
in vitro tests with head lice. In addition to pilot studies involving 21 participants, a final clinical trial, using the optimum shampoo formulation in 16 participants, demonstrated 100% effectiveness in removing head lice and nits.
The DRIFT-II dark matter detector: Design and commissioning Alner, G.J.; Araujo, H.; Bewick, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2005, Letnik:
555, Številka:
1
Journal Article
Recenzirano
DRIFT-II is a second generation multi-module gaseous dark matter detector. Each module contains two time projection chambers positioned back-to-back inside a stainless steel vacuum vessel containing ...carbon disulphide gas. This paper describes the DRIFT-II detector modules and the commissioning work performed to date.
Presented here are results of simulations of neutron background performed for a time projection chamber acting as a particle dark matter detector in an underground laboratory. The investigated ...background includes neutrons from rock and detector components, generated via spontaneous fission and (
α
,n) reactions, as well as those due to cosmic-ray muons. Neutrons were propagated to the sensitive volume of the detector and the nuclear recoil spectra were calculated. Methods of neutron background suppression were also examined and limitations to the sensitivity of a gaseous dark matter detector are discussed. Results indicate that neutrons should not limit sensitivity to WIMP-nucleon interactions down to a level of
(
1
-
3
)
×
10
-
8
pb in a 10
kg detector.
We present details of the technical design, manufacture and testing of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase xenon detector which measures both the scintillation light and ...the ionisation charge generated in the liquid by interacting particles and radiation. The instrument design is driven by both the physics requirements and by the technology requirements surrounding the use of liquid xenon. These include considerations of key performance parameters, such as the efficiency of scintillation light collection, restrictions placed on the use of materials to control the inherent radioactivity levels, attainment of high vacuum levels and chemical contamination control. The successful solution has involved a number of novel design and manufacturing features which will be of specific use to future generations of direct dark matter search experiments as they struggle with similar and progressively more demanding requirements.
The NAIAD experiment (NaI Advanced Detector) for weakly interacting massive particle (WIMP) dark matter searches at Boulby mine (UK) is described. The detector consists of an array of encapsulated ...and unencapsulated NaI(Tl) crystals with high light yield. Six crystals are collecting data at present. Data accumulated by four of them (10.6 kg
×
year exposure) have been used to set upper limits on the WIMP–nucleon spin-independent and WIMP–proton spin-dependent cross-sections. Pulse shape analysis has been applied to discriminate between nuclear recoils, as may be caused by WIMP interactions, and electron recoils due to gamma background. Various calibrations of crystals are presented.
For over a decade the Boulby Dark Matter Collaboration has been running WIMP dark matter search experiments at Boulby mine. Facilities at Boulby have recently been upgraded/expanded and the Boulby ...dark matter search programme is more active than ever. Two experiments currently in operation (ZEPLIN-I, DRIFT-I) and future large-scale experiments are planned and/or under construction (ZEPLIN II/III and DRIFT-II). Here we give an overview of the status and future plans for the Boulby dark matter search programme.
As we move to an era where next generation low-background particle physics experiments begin to be designed and constructed, the ability to assay materials with high sensitivity and at speed with a ...variety of techniques will be key. This paper describes the Mirion Technologies (Canberra) specialty ultra-low background detectors installed and commissioned at the Boulby Underground Laboratory between 2017 and 2021. The low background levels of the detectors combine with low background shielding and a radon-reduced dry nitrogen purge system to give sensitivity approaching the best in the world without the need for intricate shielding solutions. For an optimised sample geometry, run for 100 days, it would be possible to reach close to 10 \(\mu\)Bq/kg (\(10^{-12}\) g/g) for background isotopes of interest in neutrinoless double-beta decay.
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