The NEXT experiment aims to observe the neutrinoless double beta decay of xenon in a high-pressure Xe136 gas TPC using electroluminescence (EL) to amplify the signal from ionization. One of the main ...advantages of this technology is the possibility to reconstruct the topology of events with energies close to Qbb. This paper presents the first demonstration that the topology provides extra handles to reject background events using data obtained with the NEXT-DEMO prototype. Single electrons resulting from the interactions of Na22 1275 keV gammas and electron-positron pairs produced by conversions of gammas from the Th228 decay chain were used to represent the background and the signal in a double beta decay. These data were used to develop algorithms for the reconstruction of tracks and the identification of the energy deposited at the end-points, providing an extra background rejection factor of 24.3 +- 1.4 (stat.)%, while maintaining an efficiency of 66.7 +- 1% for signal events.
Neutrino- and antineutrino-oxygen neutral-current quasielastic-like interactions are measured at Super-Kamiokande using nuclear de-excitation \(\gamma\)-rays to identify signal-like interactions in ...data from a \(14.94 \ (16.35)\times 10^{20}\) protons-on-target exposure of the T2K neutrino (antineutrino) beam. The measured flux-averaged cross sections on oxygen nuclei are \(\langle \sigma_{\nu {\rm -NCQE}} \rangle = 1.70 \pm 0.17 ({\rm stat.}) ^{+ {\rm 0.51}}_{- {\rm 0.38}} ({\rm syst.}) \times 10^{-38} \ {\rm cm^2/oxygen}\) with a flux-averaged energy of 0.82 GeV and \(\langle \sigma_{\bar{\nu} {\rm -NCQE}} \rangle = 0.98 \pm 0.16 ({\rm stat.}) ^{+ {\rm 0.26}}_{- {\rm 0.19}} ({\rm syst.}) \times 10^{-38} \ {\rm cm^2/oxygen}\) with a flux-averaged energy of 0.68 GeV, for neutrinos and antineutrinos, respectively. These results are the most precise to date, and the antineutrino result is the first cross section measurement of this channel. They are compared with various theoretical predictions. The impact on evaluation of backgrounds to searches for supernova relic neutrinos at present and future water Cherenkov detectors is also discussed.
We report a measurement of the \(\nu_{\mu}\)-nucleus inclusive charged current cross section (=\(\sigma^{cc}\)) on iron using data from exposed to the J-PARC neutrino beam. The detector consists of ...14 modules in total, which are spread over a range of off-axis angles from 0\(^\circ\) to 1.1\(^\circ\). The variation in the neutrino energy spectrum as a function of the off-axis angle, combined with event topology information, is used to calculate this cross section as a function of neutrino energy. The cross section is measured to be \(\sigma^{cc}(1.1\text{ GeV}) = 1.10 \pm 0.15\) \((10^{-38}\text{cm}^2/\text{nucleon})\), \(\sigma^{cc}(2.0\text{ GeV}) = 2.07 \pm 0.27\) \((10^{-38}\text{cm}^2/\text{nucleon})\), and \(\sigma^{cc}(3.3\text{ GeV}) = 2.29 \pm 0.45\) \((10^{-38}\text{cm}^2/\text{nucleon})\), at energies of 1.1, 2.0, and 3.3 GeV, respectively. These results are consistent with the cross section calculated by the neutrino interaction generators currently used by T2K. More importantly, the method described here opens up a new way to determine the energy dependence of neutrino-nucleus cross sections.
We report the measurements of single and double differential cross section of muon neutrino charged-current interactions on carbon with a single positively charged pion in the final state at the T2K ...off-axis near detector using \(5.56\times10^{20}\) protons on target. The analysis uses data control samples for the background subtraction and the cross section signal, defined as a single negatively charged muon and a single positively charged pion exiting from the target nucleus, is extracted using an unfolding method. The model dependent cross section, integrated over the T2K off-axis neutrino beam spectrum peaking at \(0.6\)~GeV, is measured to be \(\sigma = (11.76 \pm 0.44 \text{(stat)} \pm 2.39 \text{(syst)}) \times 10^{-40} \text{cm}^2\)~\(\text{nucleon}^{-1}\). Various differential cross sections are measured, including the first measurement of the Adler angles for single charged pion production in neutrino interactions with heavy nuclei target.
This paper reports the first differential measurement of the charged-current \(\overline{\nu}_{\mu}\) interaction cross section on water with no pions in the final state. The unfolded flux-averaged ...measurement using the T2K off-axis near detector is given in double differential bins of \(\mu^+\) momentum and angle. The integrated cross section in a restricted phase space is \(\sigma=\left(1.11\pm0.18\right)\times10^{-38}\) cm\(^{2}\) per water molecule. Comparisons with several nuclear models are also presented.
We report the performance of a 10 atm Xenon/trimethylamine time projection chamber (TPC) for the detection of X-rays (30 keV) and gamma-rays (0.511-1.275 MeV) in conjunction with the accurate ...tracking of the associated electrons. When operated at such a high pressure and in 1%-admixtures, trimethylamine (TMA) endows Xenon with an extremely low electron diffusion (1.3 +-0.13 mm-sigma (longitudinal), 0.8 +-0.15 mm-sigma (transverse) along 1 m drift) besides forming a convenient Penning-Fluorescent mixture. The TPC, that houses 1.1 kg of gas in its active volume, operated continuously for 100 live-days in charge amplification mode. The readout was performed through the recently introduced microbulk Micromegas technology and the AFTER chip, providing a 3D voxelization of 8mm x 8mm x 1.2mm for approximately 10 cm/MeV-long electron tracks. This work was developed as part of the R&D program of the NEXT collaboration for future detector upgrades in the search of the 0bbnu decay in 136Xe, specifically those based on novel gas mixtures. Therefore we ultimately focus on the calorimetric and topological properties of the reconstructed MeV-electron tracks.
The identification of predictors of return home and nursing home placement in elderly patients, at the moment of admission to a Geriatric Convalescence Unit, may allow to make a discharge planning ...for these patients, and also may improve efficiency in the unit.
A number of 445 patients over 65 years were consecutively admitted to the unit. Analyzed variables at admission were; age, sex, diagnostic, comorbidity, functional status prior to admission, degree of independence in activities of daily living (Barthel index), cognitive function (Folstein Mini-Mental) and social support (modified version of social-familiar evaluation scale of Gijón). All these variables were used in two models of logistic regression analysis: 1 symbol: see text (dependent variable: return home after discharge versus other destinations), and 2 symbol: see text (dependent variable: nursing home placement on discharge versus other destinations).
The variables significatively associated with greater probability of at home discharge were: moderate dependency for activities of daily living (Barthel index = 31-59), odds ratio (OR) = 2.46 (95% confidence interval: 1.43-4.22); mild dependency (Barthel index > or = 60), OR = 3.67 (1.96-6.87); normal cognitive function (Mini-Mental > or = 21), OR = 3.14 (1.76-5.60), and a favourable social support (social-familiar scale < 12), OR = 7.33 (3.18-16.91). The only variable significatively associated with the probability of nursing home placement after discharge was an impaired social function (social-familiar scale > or = 12), OR = 4.53 (2.25-9.12).
Probability of return home after discharge is associated with functional status, cognitive function and social support. Definitively nursing home placement was only related with de degree of familiar support.
PDF
