338 research outputs found
Radiogenic and Muon-Induced Backgrounds in the LUX Dark Matter Detector
The Large Underground Xenon (LUX) dark matter experiment aims to detect rare
low-energy interactions from Weakly Interacting Massive Particles (WIMPs). The
radiogenic backgrounds in the LUX detector have been measured and compared with
Monte Carlo simulation. Measurements of LUX high-energy data have provided
direct constraints on all background sources contributing to the background
model. The expected background rate from the background model for the 85.3 day
WIMP search run is
~events~keV~kg~day
in a 118~kg fiducial volume. The observed background rate is
~events~keV~kg~day,
consistent with model projections. The expectation for the radiogenic
background in a subsequent one-year run is presented.Comment: 18 pages, 12 figures / 17 images, submitted to Astropart. Phy
Signal yields, energy resolution, and recombination fluctuations in liquid xenon
This work presents an analysis of monoenergetic electronic recoil peaks in
the dark-matter-search and calibration data from the first underground science
run of the Large Underground Xenon (LUX) detector. Liquid xenon charge and
light yields for electronic recoil energies between 5.2 and 661.7 keV are
measured, as well as the energy resolution for the LUX detector at those same
energies. Additionally, there is an interpretation of existing measurements and
descriptions of electron-ion recombination fluctuations in liquid xenon as
limiting cases of a more general liquid xenon re- combination fluctuation
model. Measurements of the standard deviation of these fluctuations at
monoenergetic electronic recoil peaks exhibit a linear dependence on the number
of ions for energy deposits up to 661.7 keV, consistent with previous LUX
measurements between 2-16 keV with H. We highlight similarities in liquid
xenon recombination for electronic and nuclear recoils with a comparison of
recombination fluctuations measured with low-energy calibration data.Comment: 11 pages, 12 figures, 3 table
Paediatric chronic suppurative otitis media in the Free State Province: Clinical and audiological features
Background. Chronic suppurative otitis media (CSOM) is a chronic infection of the middle ear cleft. In sub-Saharan Africa >50% of cases occur in children <10 years of age.Objectives. To describe the otological, audiological and bacteriological findings in children with CSOM.Methods. We conducted a prospective study at the Ear, Nose and Throat (ENT) Clinic at Universitas Academic Hospital between August 2009 and December 2010. We included all children with CSOM over this period. Patients underwent ENT and paediatric examination, and were tested for HIV. Pus swabs were taken after an ear toilet for routine microbiology, fungal and Mycobacterium tuberculosis culture. We performed audiological testing after the otorrhoea had resolved.Results. Eighty-six children (113 ears) were included, with a median age of 4.6 years (range 1 - 12 years). The mean duration of otorrhoea was 161.7 weeks (range 4 - 572 weeks). Nine patients (10.5%) presented with coalescent mastoiditis and/or intracranial complications of CSOM. Of the 153 organisms identified; Gram-negative bacteria were present in 93 (82.3%) ears, with 94.8% of these being sensitive to quinolones. Only 1 case of tuberculous otitis media was identified. HIV infection was present in 54.6% of patients tested. There was a hearing loss in 44 (66.7%) of the tested affected ears.Conclusions. There was a long delay between the onset of symptoms and accessing ENT services. Most cases of CSOM were due to quinolone-sensitive Gram-negative aerobes. There was a high prevalence of cholesteatoma, hearing loss and other complications in children in this study
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