DUNE is a new international experiment for neutrino physics and nucleon decay searches. It will consist of two detectors, about 1300 km apart, exposed to a multi-megawatt neutrino beam that will be ...built at Fermilab. One of the two detectors will be installed several hundred meters downstream of the neutrino production point with the primary role of characterising the energy spectrum and composition of the beam as well as performing precision measurements of neutrino cross sections. For the design of this so-called near detector, the DUNE Collaboration is considering, among other technologies, a pressurized argon gas time projection chamber. Such a detector, thanks to its low density and low detection thresholds, would allow the detailed measurement in argon of nuclear effects at the neutrino interaction vertex, which are considered at present one of the most important sources of systematic uncertainty for neutrino oscillation measurements.
The main purpose of this study was to longitudinally test the relationships of Self Determination Theory variables on physical activity, analyzing the model based on stages of change. The study is a ...longitudinal and quantitative research. We have developed a longitudinal cross-lagged design for structural equation models of three time points and multi-group analysis. Participants were 772 Spanish college students from the University of Zaragoza (
M
= 19.74,
SD
= 2.76) studying several degrees. Participants completed different self-reports, assessing: physical activity, stages of change, motivation and basic psychological needs, at three time points (November, January and March). The analysis indicated that intrinsic motivation positively predicted physical activity at the 3-time points, both directly and indirectly. Intrinsic motivation was negatively predicted by autonomy and positively predicted by competence (from time point 2 to 3). No relationships were found with relatedness for the entire sample. Regarding the stages of change multi-group analysis were run: in the low active group, we found a negative relationship between relatedness and physical activity, and a positive association between competence and intrinsic motivation and physical activity, whereas intrinsic motivation did not predict physical activity. Our findings showed that intrinsic motivation was the most consistent predictor of physical activity. The competence need played an essential role in intrinsic motivation and physical activity for both active and passive subjects. However, the basic psychological needs have not worked as indicated by the theory when it was examined longitudinally. The findings of the study highlight the need for different strategies to improve physical activity levels according to the stages of change.
A
bstract
The NEXT experiment aims to observe the neutrinoless double beta decay of
136
Xe in a high-pressure xenon 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
Q
ββ
. 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
22
Na 1275 keV gammas and electronpositron pairs produced by conversions of gammas from the
228
Th 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.
A new method to tag the barium daughter in the double-beta decay of ^{136}Xe is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba^{++}) ...resolution at a transparent scanning surface is demonstrated. A single-step photobleach confirms the single ion interpretation. Individual ions are localized with superresolution (∼2 nm), and detected with a statistical significance of 12.9σ over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double-beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.
A Neutrino Factory producing an intense beam composed of
ν
e
(
ν
¯
e
)
and
ν
¯
μ
(
ν
μ
)
from muon decays has been shown to have the greatest sensitivity to the two currently unmeasured neutrino ...mixing parameters,
θ
13
and
δ
CP
. Using the ‘wrong-sign muon’ signal to measure
ν
e
→
ν
μ
(
ν
¯
e
→
ν
¯
μ
)
oscillations in a 50
kt Magnetised Iron Neutrino Detector (MIND) sensitivity to
δ
CP
could be maintained down to small values of
θ
13
. However, the detector efficiencies used in these previous studies were calculated assuming perfect pattern recognition. In this paper, MIND is reassessed taking into account, for the first time, a realistic pattern recognition for the muon candidate. Reoptimisation of the analysis utilises a combination of methods, including a multivariate analysis similar to the one used in MINOS, to maintain high efficiency while suppressing backgrounds, ensuring that the signal selection efficiency and the background levels are comparable or better than the ones in previous analyses. As a result MIND remains the most sensitive future facility for the discovery of CP violation from neutrino oscillations.
Neutrinoless double beta decay (ββ0ν) is a hypothetical, very slow nuclear transition in which two neutrons undergo beta decay simultaneously and without the emission of neutrinos. The importance of ...this process goes beyond its intrinsic interest: an unambiguous observation would establish a Majorana nature for the neutrino and prove the violation of lepton number. NEXT is a new experiment to search for neutrinoless double beta decay using a radiopure high-pressure xenon gas TPC, filled with 100kg of Xe enriched in Xe-136. NEXT will be the first large high-pressure gas TPC to use electroluminescence readout with SOFT (Separated, Optimized FuncTions) technology. The design consists in asymmetric TPC, with photomultipliers behind a transparent cathode and position-sensitive light pixels behind the anode. The experiment is approved to start data taking at the Laboratorio Subterráneo de Canfranc (LSC), Spain, in 2014.
Xe–CO2 mixtures are important alternatives to pure xenon in Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification with applications in the ...important field of rare event detection such as directional dark matter, double electron capture and double beta decay detection. The addition of CO2 to pure xenon at the level of 0.05–0.1% can reduce significantly the scale of electron diffusion from 10 mm/m to 2.5 mm/m, with high impact on the discrimination efficiency of the events through pattern recognition of the topology of primary ionization trails. We have measured the electroluminescence (EL) yield of Xe–CO2 mixtures, with sub-percent CO2 concentrations. We demonstrate that the EL production is still high in these mixtures, 70% and 35% relative to that produced in pure xenon, for CO2 concentrations around 0.05% and 0.1%, respectively. The contribution of the statistical fluctuations in EL production to the energy resolution increases with increasing CO2 concentration, being smaller than the contribution of the Fano factor for concentrations below 0.1% CO2.
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