36 research outputs found

    Erratum to: Sensitivity of the DARWIN observatory to the neutrinoless double beta decay of 136^{136}Xe

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    We correct an overestimation of the production rate of 137^{137}Xe in the DARWIN detector operated at LNGS. This formerly dominant intrinsic background source is now at a level similar to the irreducible background from solar 8^8B neutrinos, thus unproblematic at the LNGS depth. The projected half-life sensitivity for the neutrinoless double beta decay (0νββ0\nu \beta \beta ) of 136^{136}Xe improves by 22%22\% compared to the previously reported number and is now T1/20ν=3.0×1027 yrT^{0\nu }_{1/2}= {3.0\times 10^{27}} \hbox { yr} (90% C.L.) after 10 years of DARWIN operation

    Granulocyte colony-stimulating factors for febrile neutropenia prophylaxis following chemotherapy: systematic review and meta-analysis

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    Background: Febrile neutropenia (FN) occurs following myelosuppressive chemotherapy and is associated with morbidity, mortality, costs, and chemotherapy reductions and delays. Granulocyte colony-stimulating factors (G-CSFs) stimulate neutrophil production and may reduce FN incidence when given prophylactically following chemotherapy. Methods: A systematic review and meta-analysis assessed the effectiveness of G-CSFs (pegfilgrastim, filgrastim or lenograstim) in reducing FN incidence in adults undergoing chemotherapy for solid tumours or lymphoma. G-CSFs were compared with no primary G-CSF prophylaxis and with one another. Nine databases were searched in December 2009. Meta-analysis used a random effects model due to heterogeneity. Results: Twenty studies compared primary G-CSF prophylaxis with no primary G-CSF prophylaxis: five studies of pegfilgrastim; ten of filgrastim; and five of lenograstim. All three G-CSFs significantly reduced FN incidence, with relative risks of 0.30 (95% CI: 0.14 to 0.65) for pegfilgrastim, 0.57 (95% CI: 0.48 to 0.69) for filgrastim, and 0.62 (95% CI: 0.44 to 0.88) for lenograstim. Overall, the relative risk of FN for any primary G-CSF prophylaxis versus no primary G-CSF prophylaxis was 0.51 (95% CI: 0.41 to 0.62). In terms of comparisons between different G-CSFs, five studies compared pegfilgrastim with filgrastim. FN incidence was significantly lower for pegfilgrastim than filgrastim, with a relative risk of 0.66 (95% CI: 0.44 to 0.98). Conclusions: Primary prophylaxis with G-CSFs significantly reduces FN incidence in adults undergoing chemotherapy for solid tumours or lymphoma. Pegfilgrastim reduces FN incidence to a significantly greater extent than filgrastim

    First Results on the Scalar WIMP-Pion Coupling, Using the XENON1T Experiment

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    Silicon Photomultipliers (SiPMs) are considered as a solid-state sensor alternative to photomultiplier tubes in experiments using liquid xenon (LXe) as a radiation detection medium. The main requirements are single-photon detection of the vacuum ultraviolet scintillation light from LXe at 178 nm with high resolution and detection efficiency and low noise rates. Further requirements for dark matter and double beta decay searches are ultra-low radioactivity levels of all the components including the substrates and cold electronics. Here we describe our characterisation of Hamamatsu 6×6 mm2 SiPMs in the temperature range 110–300 K in nitrogen gas, as well as long-term measurements in cold nitrogen gas at 172 K and liquid xenon at 185 K. After we introduce the experimental setups, the data acquisition schemes and analysis methods, we show the single-photon response, the gain versus bias voltage, as well as the dark and correlated noise rates. We demonstrate the long-term stability at cryogenic temperatures, and conclude that SiPM arrays are promising candidates for photosensor arrays in liquid xenon detectors. Furthermore, we study the radioactivity of the raw SiPM materials with gamma spectrometry and inductively coupled plasma mass spectrometry and conclude that SiPMs are suitable for use in low-background experiments

    Excess electronic recoil events in XENON1T

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    We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 tonne-years and an unprecedentedly low background rate of 76±2stat  events/(tonne×year×keV) between 1 and 30 keV, the data enable one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV. The solar axion model has a 3.4σ significance, and a three-dimensional 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by gae<3.8×10−12, gaegeffan<4.8×10−18, and gaegaγ<7.7×10−22  GeV−1, and excludes either gae=0 or gaegaγ=gaegeffan=0. The neutrino magnetic moment signal is similarly favored over background at 3.2σ, and a confidence interval of μν∈(1.4,2.9)×10−11  μB (90% C.L.) is reported. Both results are in strong tension with stellar constraints. The excess can also be explained by β decays of tritium at 3.2σ significance with a corresponding tritium concentration in xenon of (6.2±2.0)×10−25  mol/mol. Such a trace amount can neither be confirmed nor excluded with current knowledge of its production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses are decreased to 2.0σ and 0.9σ, respectively, if an unconstrained tritium component is included in the fitting. With respect to bosonic dark matter, the excess favors a monoenergetic peak at (2.3±0.2)  keV (68% C.L.) with a 3.0σ global (4.0σ local) significance over background. This analysis sets the most restrictive direct constraints to date on pseudoscalar and vector bosonic dark matter for most masses between 1 and 210  keV/c2. We also consider the possibility that 37Ar may be present in the detector, yielding a 2.82 keV peak from electron capture. Contrary to tritium, the 37Ar concentration can be tightly constrained and is found to be negligible

    Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T

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    Direct dark matter detection experiments based on a liquid xenon target are leading the search for darkmatter particles with masses above∼5GeV=c2, but have limited sensitivity to lighter masses because ofthe small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreduciblecontribution from inelastic processes accompanying the elastic scattering, which leads to the excitation andionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In thisLetter, we report on a probe of low-mass dark matter with masses down to about85MeV=c2by looking forelectronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1Texperiment. Besides the approach of detecting both scintillation and ionization signals, we exploit anapproach that uses ionization signals only, which allows for a lower detection threshold. This analysissignificantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reac

    Light Dark Matter Search with Ionization Signals in XENON1T

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    We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4  keVee, we observe 30  MeV/c2, and absorption of dark photons and axionlike particles for mχ within 0.186–1  keV/c2

    XENON1T dark matter data analysis: Signal reconstruction, calibration, and event selection

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    The XENON1T experiment at the Laboratori Nazionali del Gran Sasso is the most sensitive direct detection experiment for dark matter in the form of weakly interacting particles (WIMPs) with masses above 6  GeV/c2 scattering off nuclei. The detector employs a dual-phase time projection chamber with 2.0 metric tons of liquid xenon in the target. A one metric ton×year exposure of science data was collected between October 2016 and February 2018. This article reports on the performance of the detector during this period and describes details of the data analysis that led to the most stringent exclusion limits on various WIMP-nucleon interaction models to date. In particular, signal reconstruction, event selection, and calibration of the detector response to nuclear and electronic recoils in XENON1T are discussed

    Prevalence of amblyopia and associated refractive errors in an adult population in Victoria, Australia

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    Copyright confirmation in progress. Any queries to UMER- [email protected] study aimed to describe the prevalence of amblyopia and associated refractive errors among an adult Australian population. The Visual Impairment Project (VIP) is a population-based study of age-related eye disease in the state of Victoria, Australia. Data were collected through standardised interviews and orthoptic and ophthalmic dilated examinations. Amblyopia was defined as best-corrected visual acuity of 6/9 or worse in the absence of any pathological cause. The participants were 3,265 urban residents and 1,456 rural residents of the VIP ranging in age from 40-92 years (mean = 59 years; 53% female). The prevalence of unilateral amblyopia was 3.06 % (95% C.I. 2.59, 3.53). Amblyopia was not found to be statistically different by age group (P=0.096), gender (p=0.675), or place of birth (p=0.14). Anisometropia was statistically more common (p<0.001) in amblyopic cases (51.1% ) compared to the normal population (9.7%), and 54% of amblyopic eyes had visual acuity of worse than 6/12. Amblyopia is a significant cause of unilateral reduced visual acuity in a population aged 40 years and older. Anisometropia was more prevalent and the degree of anisometropia was greater in the amblyopic group compared with the normal population. Oblique astigmatism was more prevalent in the aIpblyopic group compared with the normal population

    Neuroprotective Effects of Recombinant T-cell Receptor Ligand in Autoimmune Optic Neuritis in HLA-DR2 Mice

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    This study examined the neuroprotective effects of T-cell receptor ligand (RTL) on autoimmune optic neuritis in humanized HLA-DR3 mice. Such immunotherapy significantly suppressed inflammation, inhibited demyelination with signs of myelin recovery, and prevented axonal loss in the optic nerves
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