18 research outputs found

    Transmission of xenon scintillation light through PTFE

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    Polytetrafluoroethylene (PTFE), also known as Teflon, is a common material used in the construction of liquid xenon detectors due to its high reflectivity for the VUV scintillation light of xenon. We present transmission measurements of PTFE for xenon scintillation light with peak emission at a wavelength of 175 nm. PTFE discs of different thicknesses are installed in front of a photosensor in two setups. One is filled with gaseous xenon, the other with liquid xenon. The measurements performed with the gaseous xenon setup at room temperature yield a transmission coefficient of λ=(350 0+60(sys)±50(stat))μm\lambda = \bigl(350{{}^{+60}_{~-0}}{}\,{\mathrm{(sys)}}\,\pm\, 50\,{\mathrm{(stat)}}\bigr)\,\mathrm{\mu m}. This is found to be in agreement with the observations made using the liquid xenon setup.Comment: 12 pages, 5 figures, 2 tables; accepted for publication in JINS

    Scintillation decay-time constants for alpha particles and electrons in liquid xenon

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    Understanding liquid xenon scintillation and ionization processes is of great interest to improve analysis methods in current and future detectors. In this paper, we investigate the dynamics of the scintillation process for excitation by O\mathcal{O}(10 keV) electrons from a 83m^{83m}Kr source and O\mathcal{O}(6 MeV) α\alpha-particles from a 222^{222}Rn source, both mixed with the xenon target. The single photon sampling method is used to record photon arrival times in order to obtain the corresponding time distributions for different applied electric fields between about 0.8 V/cm to 1.2 kV/cm. Energy and field dependences of the signals which are observed in the results are discussed.Comment: 11 pages, 9 figures; replaced with published manuscript versio

    Characterization of alpha and beta interactions in liquid xenon

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    Liquid xenon based detectors have achieved great sensitivities in rare event searches. Precise knowledge of the scintillation and ionization responses of the medium is essential to correctly model different interaction types in the detector including both signal and background-like ones. The response of liquid xenon to low energy electrons and to alpha particles has been studied in the Heidelberg Xenon (HeXe) dual-phase xenon TPC. We determine the light and charge signal yields for keV-energy electrons and MeV-energy alpha particles as well as the electron drift velocity for electric drift fields between 7.5 and 1640 V/cm. A three dimensional simulation using COMSOL Multiphysics(R) is used to characterize the applied drift field and its homogeneity.Comment: 16 pages, 21 figures. Associated data is available under https://doi.org/10.5281/zenodo.552521

    Production and characterization of a 222^{222}Rn-emanating stainless steel source

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    Precise radon measurements are a requirement for various applications, ranging from radiation protection over environmental studies to material screening campaigns for rare-event searches. All of them ultimately depend on the availability of calibration sources with a known and stable radon emanation rate. A new approach to produce clean and dry radon sources by implantation of 226^{226}Ra ions into stainless steel has been investigated. In a proof of principle study, two stainless steel plates have been implanted in collaboration with the ISOLDE facility located at CERN. We present results from a complete characterization of the sources. Each sample provides a radon emanation rate of about 2 Bq, which has been measured using electrostatic radon monitors as well as miniaturized proportional counters. Additional measurements using HPGe and alpha spectrometry as well as measurements of the radon emanation rate at low temperatures were carried out.Comment: 8 pages, 11 figures, 8th ICRM-LLRMT conference (2022

    Prenatal prediction of pulmonary hypoplasia: US and MR imaging working together [1]

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    SCOPUS: le.jinfo:eu-repo/semantics/publishe

    Incidence and risk factors of acute kidney injury associated with continuous intravenous high-dose vancomycin in critically ill patients: A retrospective cohort study

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    For vancomycin therapy of severe infections, the Infectious Diseases Society of America recommends high vancomycin trough levels, whose potential for inducing nephrotoxicity is controversial. We evaluated the incidence and risk factors of acute kidney injury (AKI) in critically ill patients given continuous intravenous vancomycin with target serum vancomycin levels of 20 to 30mg/L. We retrospectively studied 107 continuous intravenous vancomycin treatments of ≥48 hours' duration with at least 2 serum vancomycin levels ≥20mg/L in critically ill patients. Nephrotoxicity was defined according to the Kidney Disease Improving Global Outcomes Clinical Practice Guideline for AKI (ie, serum creatinine elevation by ≥26.5mmoL/L or to ≥1.5 times baseline). Risk factors for AKI were identified by univariate and multivariate analyses. AKI developed in 31 (29%) courses. Higher serum vancomycin levels were associated with AKI (P<0.01). Factors independently associated with AKI were highest serum vancomycin ≥40mg/L (odds ratio [OR], 3.75; 95% confidence interval [CI], 1.40-10.37; P< 0.01), higher cumulative number of organ failures (OR, 2.63 95%CI, 1.42-5.31; P<0.01), and cirrhosis of the liver (OR, 5.58; 95%CI, 1.08-31.59; P=0.04). In this study, 29% of critically ill patients had AKI develop during continuous intravenous vancomycin therapy targeting serum levels of 20 to 30mg/L. Serum vancomycin level ≥40mg/L was independently associated with AKI.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Prenatal prognosis of congenital diaphragmatic hernia using magnetic resonance imaging measurement of fetal lung volume

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    Objectives: To investigate the correlation between fetal lung volume (FLV), measured with magnetic resonance imaging (MRI), and postnatal mortality in newborns with prenatally diagnosed isolated congenital diaphragmatic hernia (CDH). Methods: In a 4-year prospective multicenter study, 77 fetuses with isolated CDH diagnosed between 20 and 33 weeks' gestation underwent fast spin-echo T2-weighted lung MRI. These MRI-FLV measurements were compared with a previously published normative curve obtained in 215 fetuses without thoracoabdominal malformations and with normal ultrasound biometric findings. FLV measurements were correlated with postnatal survival. The mean gestational age at MRI was 31.3 weeks. Results: The measured/expected FLV ratio was significantly lower in the newborns with CDH who died compared with those who survived (23.6 ± 12.2 vs. 36.1 ± 13.0, P < 0.001). When the ratio was below 25%, there was a significant decrease in postnatal survival (19% vs. 40.3%, P = 0.008). Survival was significantly lower for neonates when one lung could not be seen by fetal MRI compared with those fetuses with two visible lungs on MRI (17.9% vs. 62.1%, P < 0.001). Conclusion: In isolated CDH, FLV measurement by MRI is a good predictor of postnatal mortality due to pulmonary hypoplasia. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

    Neutron detection and application with a novel 3D-projection scintillator tracker in the future long-baseline neutrino oscillation experiments

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    Neutrino oscillation experiments require a precise measurement of the neutrino energy. However, the kinematic detection of the final-state neutron in the neutrino interaction is missing in current neutrino oscillation experiments. The missing neutron kinematic detection results in a smaller detected neutrino energy than the true neutrino energy. A novel 3D-projection scintillator tracker, which consists of roughly ten million active cubes covered with an optical reflector, is capable of measuring the neutron kinetic energy and direction on an event-by-event basis using the time-of-flight technique thanks to the fast timing, fine granularity, and high light yield. The ν¯μ interactions tend to produce neutrons in the final state. By measuring the neutron kinetic energy, the ν¯μ energy can be reconstructed better, allowing a tighter incoming neutrino flux constraint. This article shows the detector's ability to reconstruct neutron kinetic energy and the ν¯μ flux constraint achieved by selecting the charged-current interactions without mesons or protons in the final state.ISSN:1550-7998ISSN:0556-2821ISSN:1550-236
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