E. J. Barnes

Bio: E. J. Barnes is an academic researcher from University of Edinburgh. The author has contributed to research in topics: ZEPLIN-III & Scintillation. The author has an hindex of 14, co-authored 21 publications receiving 942 citations.

Results from the first science run of the ZEPLIN-III dark matter search experiment

Abstract: The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses a 12 kg two-phase xenon time-projection chamber to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy. The detector measures both scintillation and ionization produced by radiation interacting in the liquid to differentiate between the nuclear recoils expected from WIMPs and the electron-recoil background signals down to ∼10keV nuclear-recoil energy. An analysis of 847kg•days of data acquired between February 27, 2008, and May 20, 2008, has excluded a WIMP-nucleon elastic scattering spin-independent cross section above 8.1×10-8pb at 60GeVc-2 with a 90% confidence limit. It has also demonstrated that the two-phase xenon technique is capable of better discrimination between electron and nuclear recoils at low-energy than previously achieved by other xenon-based experiments. © 2009 The American Physical Society.

Limits on the spin-dependent WIMP-nucleon cross sections from the first science run of the ZEPLIN-III experiment.

Abstract: We present new experimental constraints on the WIMP-nucleon spin-dependent elastic cross sections using data from the first science run of ZEPLIN-III, a two-phase xenon experiment searching for galactic dark matter weakly interacting massive particles based at the Boulby mine. Analysis of approximately 450 kg x days fiducial exposure allow us to place a 90%-confidence upper limit on the pure WIMP-neutron cross section of sigma(n)=1.9x10(-2) pb at 55 GeV/c(2) WIMP mass. Recent calculations of the nuclear spin structure based on the Bonn charge-dependent nucleon-nucleon potential were used for the odd-neutron isotopes 129Xe and 131Xe. These indicate that the sensitivity of xenon targets to the spin-dependent WIMP-proton interaction could be much lower than implied by previous calculations, whereas the WIMP-neutron sensitivity is impaired only by a factor of approximately 2.

Position reconstruction in a dual phase xenon scintillation detector

Abstract: We studied the application of statistical reconstruction algorithms, namely maximum likelihood and least squares methods, to the problem of event reconstruction in a dual phase liquid xenon detector An iterative method was developed for in-situ reconstruction of the PMT light response functions from calibration data taken with an uncollimated γ -ray source Using the techniques described, the performance of the ZEPLIN-III dark matter detector was studied for 122 keV γ-rays For the inner part of the detector (R <; 100 mm) , spatial resolutions of 13 mm and 16 mm FWHM were measured in the horizontal plane for primary and secondary scintillation, respectively An energy resolution of 81% FWHM was achieved at that energy The possibility of using this technique for improving performance and reducing cost of scintillation cameras for medical applications is currently under study

Single electron emission in two-phase xenon with application to the detection of coherent neutrino-nucleus scattering

Abstract: We present an experimental study of single electron emission in ZEPLIN-III, a two-phase xenon experiment built to search for dark matter WIMPs, and discuss appli-cations enabled by the excellent signal-to-noise ratio achieved in detecting this signature. Firstly, we demonstrate a practical method for precise measurement of the free electron lifetime in liquid xenon during normal operation of these detectors. Then, using a realistic detector response model and backgrounds, we assess the feasibility of deploying such an instrument for measuring coherent neutrino-nucleus elastic scattering using the ionisation channel in the few-electron regime. We conclude that it should be possible to measure this elusive neutrino signature above an ionisation threshold of ~3 electrons both at a stopped pion source and at a nuclear reactor. Detectable signal rates are larger in the reactor case, but the triggered measurement and harder recoil energy spectrum afforded by the accelerator source enable lower overall background and fiducialisation of the active volume.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Dark Matter Candidates from Particle Physics and Methods of Detection

Abstract: The identity of dark matter is a question of central importance in both astrophysics and particle physics. In the past, the leading particle candidates were cold and collisionless, and typically predicted missing energy signals at particle colliders. However, recent progress has greatly expanded the list of well-motivated candidates and the possible signatures of dark matter. This review begins with a brief summary of the standard model of particle physics and its outstanding problems. We then discuss several dark matter candidates motivated by these problems, including WIMPs, superWIMPs, light gravitinos, hidden dark matter, sterile neutrinos, and axions. For each of these, we critically examine the particle physics motivations and present their expected production mechanisms, basic properties, and implications for direct and indirect detection, particle colliders, and astrophysical observations. Upcoming experiments will discover or exclude many of these candidates, and progress may open up an era of unprecedented synergy between studies of the largest and smallest observable length scales.

Dark Matter Candidates from Particle Physics and Methods of Detection

Abstract: The identity of dark matter is a question of central importance in both astrophysics and particle physics. In the past, the leading particle candidates were cold and collisionless, and typically predicted missing energy signals at particle colliders. However, recent progress has greatly expanded the list of well-motivated candidates and the possible signatures of dark matter. This review begins with a brief summary of the standard model of particle physics and its outstanding problems. I then discuss several dark matter candidates motivated by these problems, including weakly interacting massive particles (WIMPs), superWIMPs, light gravitinos, hidden dark matter, sterile neutrinos, and axions. For each of these, I critically examine the particle physics motivations and present their expected production mechanisms, basic properties, and implications for direct and indirect detection, particle colliders, and astrophysical observations. Upcoming experiments will discover or exclude many of these candidates, and progress may open up an era of unprecedented synergy between studies of the largest and smallest observable length scales.

Dark matter search results from the CDMS II experiment.

Abstract: We report results from a blind analysis of the final data taken with the Cryogenic Dark Matter Search experiment (CDMS II) at the Soudan Underground Laboratory, Minnesota, USA. A total raw exposure of 612 kg-days was analyzed for this work. We observed two events in the signal region; based on our background estimate, the probability of observing two or more background events is 23%. These data set an upper limit on the Weakly Interacting Massive Particle (WIMP)-nucleon elastic-scattering spin-independent cross-section of 7.0 x 10{sup -44} cm{sup 2} for a WIMP of mass 70 GeV/c{sup 2} at the 90% confidence level. Combining this result with all previous CDMS II data gives an upper limit on the WIMP-nucleon spin-independent cross-section of 3.8 x 10{sup -44} cm{sup 2} for a WIMP of mass 70 GeV/c{sup 2}. We also exclude new parameter space in recently proposed inelastic dark matter models.