( )ħ: The traditional blues tale Gallows Pole that opens side two was discovered by Page on an album titled 12 String Guitar released in 1962 by American acoustic performer Fred Gerlach. Plant also leaned on that source for inspiration on Custard Pie, the opening track on 1975’s Physical Graffiti album.
( )Ħ: The lyrics of Hats Off To (Roy) Harper are based on Bukka White’s 1937 recording Shake Em On Down. In conjunction with the replacement of the internal ZEPLIN-III photomultiplier array, the new veto is expected to improve significantly the sensitivity of the ZEPLIN-III instrument to dark matter, allowing spin-independent WIMP-nucleon cross sections below 10−8 pb to be probed.5: A cover version of Immigrant Song by Nine Inch Nails’ Trent Reznor featuring Yeah Yeahs Karen O was used on the soundtrack of the David Fincher film The Girl With the Dragon Tattoo. Furthermore, in addition to providing valuable diagnostic capabilities, the veto is capable of tagging over 15% for γ-ray rejection, all whilst contributing no significant additional background. This will reduce the background in ZEPLIN-III from ≃0.4 to ≃0.14 events per year in the WIMP acceptance region, a significant factor in the event of a non-zero observation. The veto device will be capable of rejecting over 65% of coincident nuclear recoil events from neutron background in the energy range of interest in ZEPLIN-III. These have been used to inform a complete end-to-end Monte Carlo simulation that has then been used to calculate the expected performance of the new instrument, both operating alone and as an anti-coincidence detector for ZEPLIN-III. Extensive experimental measurements of the components have been made, including radioactivity levels and performance characteristics. The overall aim has been to achieve a veto detector of low threshold and high efficiency without the creation of additional background in ZEPLIN-III, all at a reasonable cost. Particular attention has been paid to radiological content. One tonne of plastic scintillator is arranged into 52 bars individually read out by photomultipliers and coupled to a gadolinium-loaded passive polypropylene shield. The design, optimisation and construction of an anti-coincidence veto detector to complement the ZEPLIN-III direct dark matter search instrument is described. Variations in photocathode thickness from tube to tube could account for this behaviour, as well as the fact that the quantum efficiency improves the most for devices with poorest efficiency at room temperature. Saturation of response due to accumulation of charge in the resistive bialkali photocathodes was seen at an average photocurrent of 108photoelectrons/s for the device with best quantum efficiency, whereas an order of magnitude higher current was required to saturate the least sensitive one. A general improvement of both gain and quantum efficiency at the xenon scintillation wavelength was observed with cooling, the best combined effect being 40%, while little change was noted in the timing properties and dark current. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.Ī set of 35 photomultiplier tubes (ETL D730/9829Q), intended for use in the ZEPLIN III Dark Matter detector, was tested from room temperature down to −100☌, with the aim of confirming their suitability for detecting xenon scintillation light at 175nm while immersed in the cryogenic liquid. The second science run should offer an order of magnitude improvement in sensitivity.
#Zeplin iii upgrade#
The upgrade includes replacement of the PMT array and the addition of an active veto for gammas and neutrons. ZEPLIN-III demonstrated better discrimination at low-energy than previously achieved by any other xenon-based experiments and highlighted a non-linearity in the low-energy response to nuclear recoils. The frst science run obtained 847kgdays of data acquired between February 27th 2008 and May 20th 2008 and excluded a WIMP-nucleon elastic scattering spin-independent cross-section above 8.1 × 10-8pb at 60 GeVc-2 with a 90% confdence limit. This paper reviews the science results obtained from the frst science run and reports on the current status of the upgrade and second science run.
The detector measures both scintillation and ionisation produced interactions in the liquid to differentiate between nuclear recoils expected from WIMPs and electron recoil background signals down to ∼10 keV nuclear recoil energy. ZEPLIN-III is a 12 kg two-phase xenon time projection chamber used to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy.
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