The measurement of the internal \(^{222}\)Rn activity in the NEXT-White detector during the so-called Run-II period with \(^{136}\)Xe-depleted xenon is discussed in detail, together with its ...implications for double beta decay searches in NEXT. The activity is measured through the alpha production rate induced in the fiducial volume by \(^{222}\)Rn and its alpha-emitting progeny. The specific activity is measured to be \((38.1\pm 2.2~\mathrm{(stat.)}\pm 5.9~\mathrm{(syst.)})\)~mBq/m\(^3\). Radon-induced electrons have also been characterized from the decay of the \(^{214}\)Bi daughter ions plating out on the cathode of the time projection chamber. From our studies, we conclude that radon-induced backgrounds are sufficiently low to enable a successful NEXT-100 physics program, as the projected rate contribution should not exceed 0.1~counts/yr in the neutrinoless double beta decay sample.
One of the major goals of the NEXT-White (NEW) detector is to demonstrate the energy resolution that an electroluminescent high pressure xenon TPC can achieve for high energy tracks. For this ...purpose, energy calibrations with 137Cs and 232Th sources have been carried out as a part of the long run taken with the detector during most of 2017. This paper describes the initial results obtained with those calibrations, showing excellent linearity and an energy resolution that extrapolates to approximately 1% FWHM at Q\(_{\beta\beta}\).
Gaseous time projection chambers (TPC) are a very attractive detector technology for particle tracking. Characterization of both drift velocity and diffusion is of great importance to correctly ...assess their tracking capabilities. NEXT-White is a High Pressure Xenon gas TPC with electroluminescent amplification, a 1:2 scale model of the future NEXT-100 detector, which will be dedicated to neutrinoless double beta decay searches. NEXT-White has been operating at Canfranc Underground Laboratory (LSC) since December 2016. The drift parameters have been measured using \(^{83m}\)Kr for a range of reduced drift fields at two different pressure regimes, namely 7.2 bar and 9.1 bar. The results have been compared with Magboltz simulations. Agreement at the 5% level or better has been found for drift velocity, longitudinal diffusion and transverse diffusion.
The Fermilab Tevatron collider's data-taking run ended in September 2011, yielding a dataset with rich scientific potential. The CDF and D0 experiments each have approximately 9 PB of collider and ...simulated data stored on tape. A large computing infrastructure consisting of tape storage, disk cache, and distributed grid computing for physics analysis with the Tevatron data is present at Fermilab. The Fermilab Run II data preservation project intends to keep this analysis capability sustained through the year 2020 and beyond. To achieve this goal, we have implemented a system that utilizes virtualization, automated validation, and migration to new standards in both software and data storage technology and leverages resources available from currently-running experiments at Fermilab. These efforts have also provided useful lessons in ensuring long-term data access for numerous experiments, and enable high-quality scientific output for years to come.
The Next White (NEW) detector Monrabal, F; Gómez-Cadenas, J J; Toledo, J F ...
arXiv.org,
04/2018
Paper, Journal Article
Odprti dostop
Conceived to host 5 kg of xenon at a pressure of 15 bar in the fiducial volume, the NEXT- White (NEW) apparatus is currently the largest high pressure xenon gas TPC using electroluminescent ...amplification in the world. It is also a 1:2 scale model of the NEXT-100 detector scheduled to start searching for \(\beta\beta 0\nu\) decays in 136Xe in 2019. Both detectors measure the energy of the event using a plane of photomultipliers located behind a transparent cathode. They can also reconstruct the trajectories of charged tracks in the dense gas of the TPC with the help of a plane of silicon photomultipliers located behind the anode. A sophisticated gas system, common to both detectors, allows the high gas purity needed to guarantee a long electron lifetime. NEXT-White has been operating since October 2017 at the Canfranc Underground Laboratory (LSC), in Spain. This paper describes the detector and associated infrastructures.
The NEXT-White (NEW) detector is currently the largest radio-pure
high-pressure xenon gas time projection chamber with electroluminescent readout
in the world. NEXT-White has been operating at ...Laboratorio Subterr\'aneo de
Canfranc (LSC) since October 2016. This paper describes the calibrations
performed with $^{83m}\mathrm{Kr}$ decays during a long run taken from March to
November 2017 (Run II). Krypton calibrations are used to correct for the finite
drift-electron lifetime as well as for the dependence of the measured energy on
the event position which is mainly caused by variations in solid angle
coverage. After producing calibration maps to correct for both effects we
measure an excellent energy resolution for 41.5 keV point-like deposits of
(4.553 $\pm$ 0.010 (stat.) $\pm$ 0.324 (sys.)) % FWHM in the full chamber and
(3.804 $\pm$ 0.013 (stat.) $\pm$ 0.112 (sys.)) % FWHM in a restricted fiducial
volume. Using naive 1/$\sqrt{E}$ scaling, these values translate into
resolutions of (0.516 $\pm$ 0.0014 (stat.) $\pm$ 0.0421 (sys.)) % FWHM and
(0.4943 $\pm$ 0.0017 (stat.) $\pm$ 0.0146 (sys.)) % FWHM at the
$Q_{\beta\beta}$ energy of xenon double beta decay (2458 keV), well within
range of our target value of 1%.
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 has been demonstrated. A single-step photo-bleach confirms the single ion interpretation. Individual ions are localized with super-resolution (\(\sim\)2~nm), and detected with a statistical significance of 12.9~\(\sigma\) 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.
We present the results of a search for leptoquark (LQ) pairs in (85.2 +- 3.7) pb^{-1} of p anti-p collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for ...leptoquark production and set a limit on sigma(p anti-p -> LQ anti-LQ -> neutrino neutrino + jets) as a function of the mass of the leptoquark (m_{LQ}). Assuming the decay LQ -> neutrino q, we exclude scalar leptoquarks for m_{LQ} < 98 GeV/c^2, and vector leptoquarks for m_{LQ} < 200 GeV/c^2 and coupling which produces the minimum cross section, at a 95% confidence level.
We have performed a search for scalar top quark (stop) pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of $p \bar{p}$ events corresponding to ...108.3 pb$^{-1}$ of data collected with the D{\O}detector at Fermilab. The search is done in the framework of the minimal supersymmetric standard model assuming that the sneutrino is the lightest supersymmetric particle. For the dominant decays of the lightest stop, \bc and \bls, no evidence for signal is found. We derive cross-section limits as a function of stop (\stt), chargino (\ca), and sneutrino (\snu) masses.
We report the first search for supersymmetric particles via s-channel production and decay of smuons or muon sneutrinos at hadronic colliders. The data for the two-muon and two-jets final states were ...collected by the DO experiment, and correspond to an integrated luminosity of 94 +/- 5 pb^{-1}. Assuming that R-parity is violated via the single coupling lambda^{prime}_{211}, the number of candidate events is in agreement with expectation from the standard model. Exclusion contours are given in the (m_0,m_{1/2}) and (m_{tilde{chi}},m_{tilde{nu}}) planes for lambda^{prime}_{211}=0.09, 0.08 and 0.07.
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