Material screening and selection for XENON100

A: The "Neutrino Experiment with a Xenon Time-Projection Chamber" (NEXT) experiment intends to investigate the neutrinoless double beta decay of 136 Xe, and therefore requires a severe suppression of potential backgrounds. An extensive material screening and selection process was undertaken to quantify the radioactivity of the materials used in the experiment. Separate energy and tracking readout planes using different sensors allow us to combine the measurement of the topological signature of the event for background discrimination with the energy resolution optimization. The design of radiopure readout planes, in direct contact with the gas detector medium, was especially challenging since the required components typically have activities too large for experiments demanding ultra-low background conditions. After studying the tracking plane, here the radiopurity control of the energy plane is presented, mainly based on gamma-ray spectroscopy using ultra-low background germanium detectors at the Laboratorio Subterráneo de Canfranc (Spain). All the available units of the selected model of photomultiplier have been screened together with most of the components for the bases, enclosures and windows. According to these results for the activity of the relevant radioisotopes, the selected components of the energy plane would give a contribution to the overall background level in the region of interest of at most 2.4 × 10 −4 counts keV −1 kg −1 y −1 , satisfying the sensitivity requirements of the NEXT experiment.

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“…[20,30]; results are roughly consistent taking into account that the volume of SM5 resistors is four times the one of SM2 resistors.…”

Section: Pmt Basessupporting

confidence: 71%

Radiopurity assessment of the energy readout for the NEXT double beta decay experiment

et al. 2017

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“…The flux of radioactive decay particles from rock and concrete in LNGS halls is assumed to be 1 γ / cm 2 / s [20,21] and 5 · 10 −6 neutrons / cm 2 / s [21,22]. For the radioactive contamination of the stainless steel we use the results in [23], conservatively multiplied by a factor 100. A dedicated Monte Carlo shows that the only important contribution comes from γ emitted in the rock, which on average induce on each PMT a rate of R b ∼2000 PE/s.…”

Section: Expected Trigger Rate For the Muon Vetomentioning

confidence: 99%

Conceptual design and simulation of a water Cherenkov muon veto for the XENON1T experiment

Aprile

Agostini²,

Alfonsi³

et al. 2014

J. Inst.

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XENON is a dark matter direct detection project, consisting of a time projection chamber (TPC) filled with liquid xenon as detection medium. The construction of the next generation detector, XENON1T, is presently taking place at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. It aims at a sensitivity to spin-independent cross sections of 2·10 −47 cm 2 for WIMP masses around 50 GeV/c 2 , which requires a background reduction by two orders of magnitude compared to XENON100, the current generation detector. An active system that is able to tag muons and muon-induced backgrounds is critical for this goal. A water Cherenkov detector of ∼10 m height and diameter has been therefore developed, equipped with 8 inch photomultipliers and cladded by a reflective foil. We present the design and optimization study for this detector, which has been carried out with a series of Monte Carlo simulations. The muon veto will reach very high detection efficiencies for muons (> 99.5%) and showers of secondary particles from muon interactions in the rock (> 70%). Similar efficiencies will be obtained for XENONnT, the upgrade of XENON1T, which will later improve the WIMP sensitivity by another order of magnitude. With the Cherenkov water shield studied here, the background from muon-induced neutrons in XENON1T is negligible.

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“…These PMTs are the first low background-designed commercial PMTs, thus their measurements are expected to provide very valuable information to the low background community. In addition, a comparison to previous measurements by LUX (≈ 0.7 mBq/PMT) [9] and XENON (≈ 5 mBq/PMT) [10] Collaborations, will give important information about reproducibility in the fabrication process and explain this difference. Because of the large size of the sample and the limited measurement time, all the PMTs in a mode pass/don't pass are being measured at the moment.…”

Section: Pmt Campaignmentioning

confidence: 99%

The NEXT-100 experiment for Neutrinoless Double Beta decay: Main features, Results from Prototypes and Radio-Purity issues.

Pérez¹

2014

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP 2013)

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Abstract:The NEXT-100 time projection chamber, currently under construction, will search for neutrinoless double beta decay (2β0ν) using 100kg at 15bar of high-pressure xenon gas enriched in the 136 Xe isotope to 90%. It will be running in the Canfranc Underground Laboratory (LSC) under the Pyrenees in Spain. The detector possesses two important features for 2β0ν searches: very good energy resolution (better than 1% FWHM at the Q values of the 136 Xe) and event topological information for the distinction between signal and background. Furthermore, the technique can be extrapolated to the ton-scale, thus allowing the full exploration of the inverted hierarchy of neutrino masses. First prototypes have been operating successfully in different laboratories.I will discuss the main features of NEXT-100 and the prototype results concerning energy resolution, track pattern recognition and xenon gas ionization and scintillation properties obtained with a variety of radioactive sources. We will present as well the main results so far on radioactive contamination of the materials to be used in NEXT-100, including the status of the measurement campaign of its 60 low-radioactivity Photo Multipliers Hamamatsu R11410-10.

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Material screening and selection for XENON100

Cited by 99 publications

References 31 publications

Radiopurity assessment of the energy readout for the NEXT double beta decay experiment

Radiopurity assessment of the energy readout for the NEXT double beta decay experiment

Conceptual design and simulation of a water Cherenkov muon veto for the XENON1T experiment

The NEXT-100 experiment for Neutrinoless Double Beta decay: Main features, Results from Prototypes and Radio-Purity issues.

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