A high pressure xenon gas time projection chamber with electroluminescent amplification (EL HPGXe TPC) searching for the neutrinoless double beta (0νββ) decay offers: excellent energy resolution 1, 2 ...(0.5 − 0.7% FWHM at the Qββ), by amplifying the ionization signal with electroluminescent light, and tracking capabilities 3, as demonstrated by the NEXT collaboration using two kg-scale prototypes. The NEXT collaboration is building an EL HPGXe TPC capable of holding 100 kg (NEXT-100) of xenon isotopically enriched in 136Xe. The installation and commissioning of the NEXT-100 detector at the Laboratorio Subterráneo de Canfranc (LSC) is planned for 2018. The current estimated background level for the NEXT-100 detector is of 4 × 10−4 counts/keV-kg-yr or less in the energy region of interest 4. Assuming an energy resolution of 0.75% FWHM at the Qνββ and a 0νββ signal efficiency of about 28%, this gives an expected sensitivity (at 90% CL) to the 0νββ decay half life of T 1 / 2 0 ν > 6.0 × 10 25 yr for an exposure of 275 kg yr. A first phase of the NEXT experiment, called NEW, is currently being commissioned at the LSC. The NEW detector is a scale 1:2 in size (1:10 in mass) of the NEXT-100 detector using the same materials and photosensors and will be used to perform a characterization of the 0νββ backgrounds and a measurement of the standard double beta decay with neutrinos (2ν ββ). An 8 sigma significance for the 2νββ signal in the NEW detector has been estimated for a 100-day run.
A high pressure xenon gas time projection chamber with electroluminescent amplification (EL HPGXe TPC) offers for the search of the neutrinoless double beta decay (0νββ): an excellent energy ...resolution (0.5−0.7% FWHM at the Qββ) and tracking capabilities as demonstrated by the NEXT collaboration using two kg-scale prototypes. The NEXT collaboration is constructing an EL HPGXe TPC capable to hold 100 kg (NEXT-100) of xenon isotopically enriched in 136Xe. Since October 2016, a first phase of the NEXT experiment, called NEW detector, is running with depleted 136Xe at the Laboratorio Subterraneo de Canfranc. The NEW detector is a scale 1:2 in size of the NEXT-100 detector and uses same materials and photosensors. It will be used to perform a characterization of the 0νββ backgrounds and a measurement of the standard double beta decay rate. Recent results on the characterization of the NEW detector performance using data from calibration sources are presented.
Within the framework of xenon-based double beta decay experiments, we propose the possibility to improve the background rejection of an electroluminescent Time Projection Chamber (EL TPC) by reducing ...the diffusion of the drifting electrons while keeping nearly intact the energy resolution of a pure xenon EL TPC. Based on state-of-the-art microscopic simulations, a substantial addition of helium, around 10 or 15 %, may reduce drastically the transverse diffusion down to 2.5 mm/m from the 10.5 mm/m of pure xenon. The longitudinal diffusion remains around 4 mm/m. Light production studies have been performed as well. They show that the relative variation in energy resolution introduced by such a change does not exceed a few percent, which leaves the energy resolution practically unchanged. The technical caveats of using photomultipliers close to an helium atmosphere are also discussed in detail.
This study explores the differences in sickness absence trends in women according to reproductive age group and medical diagnoses.
Data were obtained from two administrative registries: the ...Continuous Working Life Sample and the Catalonian Institute of Medical Evaluations from 2012 to 2014, containing 47,879 female employees. Incidence rates and incidence risk ratios derived from Poisson and negative binomial models were calculated to compare sickness absence trends among reproductive age groups based on Catalonian birthrates: early-reproductive (25-34 years old), middle-reproductive (35-44) and late-reproductive (45-54), according to diagnostic groups, selected diseases, type of contract, occupational category, and country of origin.
Younger women show a higher incidence of overall sickness absence compared to late-reproductive-aged women. Incidence risk ratios of sickness absence decreased significantly from early-reproductive to late-reproductive age for low back pain, hemorrhage in early pregnancy, nausea and vomiting, and abdominal and pelvic pain.
The higher incidence of sickness absence due to pregnancy-related health conditions in early-reproductive women compared to other reproductive age groups, may explain the sickness absence differences by age in women. Proper management of sickness absence related to pregnancy should be a goal to reduce the sickness absence gap between younger and older women.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We have studied the relative stability of narrow-finite length Carbon nanotubes and nanostrips as a function of their length. We find that the critical radius (∼2
Å) for tube stability is independent ...of the length of the tubes and equals the critical radius of infinite length tubes. The independence of the critical radius on chirality is also established. We have also investigated the thermal stability of short nanotubes and nanostrips by performing extensive molecular dynamics simulations. The strips exhibit a higher thermal stability than the tubes even in those cases when they are structurally less stable. The thermal decomposition temperature (∼1000
K) of the tubes comes out in good agreement with the experiments.
A
bstract
The
Neutrino Experiment with a Xenon TPC
(NEXT) searches for the neutrinoless double-beta (0
νββ
) decay of
136
Xe using high-pressure xenon gas TPCs with electroluminescent amplification. ...A scaled-up version of this technology with about 1 tonne of enriched xenon could reach in less than 5 years of operation a sensitivity to the half-life of 0
νββ
decay better than 10
27
years, improving the current limits by at least one order of magnitude. This prediction is based on a well-understood background model dominated by radiogenic sources. The detector concept presented here represents a first step on a compelling path towards sensitivity to the parameter space defined by the inverted ordering of neutrino masses, and beyond.
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
bstract
NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0
νββ
) decay of
136
Xe. The detector possesses two ...features of great value for 0
νββ
searches: energy resolution better than 1% FWHM at the
Q
value of
136
Xe and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4 × 10
−4
counts keV
−1
kg
−1
yr
−1
. Accordingly, the detector will reach a sensitivity to the 0
νββ
-decay half-life of 2.8 × 10
25
years (90% CL) for an exposure of 100 kg·year, or 6.0 × 10
25
years after a run of 3 effective years.
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