Trace radioactive impurities in final construction materials for EXO-200

LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above $${1.4 \times 10^{-48}}\, {\hbox {cm}}^{2}$$ 1.4 × 10 - 48 cm 2 for a WIMP mass of $${40}\, \hbox {GeV}/{\hbox {c}}^{2}$$ 40 GeV / c 2 and a $${1000}\, \hbox {days}$$ 1000 days exposure. LZ achieves this sensitivity through a combination of a large $${5.6}\, \hbox {t}$$ 5.6 t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented.

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“…This allows to reference the elements of interest directly to a standard. This method is discussed in depth in [20].…”

Section: Neutron Activation Analysis (Naa)mentioning

confidence: 99%

The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs

et al. 2020

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“…This assessment was based on the determination of the radioactivity content of all detector components, coupled with a Geant3.21 based detector simulation to compute event rates. All detector components went through a detailed and comprehensive material screening and selection program [21,22]. The EXO-200 collaboration adopted a background goal for events near the 0νββ Q-value, which in turn determined the allowable 60 Co, 232 Th and 238 U content of the detector.…”

Section: Exo-200 Experimentsmentioning

confidence: 99%

“…This is essential for the iterative development of a compelling and realistic experiment concept. nEXO's approach follows the example of the successful EXO-200 materials certification and background estimation efforts [21,22].…”

Section: B Detector Component Materials and Assaysmentioning

confidence: 99%

Sensitivity and discovery potential of the proposed nEXO experiment to neutrinoless double- β decay

Albert¹,

Anton²,

Arnquist³

et al. 2018

Phys. Rev. C

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198

196

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“…"Enriched Xenon Observatory" (EXO), located at WIPP, in New Mexico, USA, has developed liquid xenon TPCs. The detector of EXO-200 contained 200 kg of enriched xenon (80.6% of 136 Xe) having wire planes and avalanche photodiodes at the two ends of the cylindrical chamber to read charge and light, respectively; it was built from carefully selected radiopure materials [148] and produced important results [149]. For the two-neutrino DBD channel of 136 Xe, a half-life shorter than expectations was confirmed [150], while, for the neutrinoless mode, the 90% C.L.…”

Section: Xenon Dbd Experimentsmentioning

confidence: 99%

Cosmogenic Activation in Double Beta Decay Experiments

Cebrián

2020

Universe

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Double beta decay is a very rare nuclear process and, therefore, experiments intended to detect it must be operated deep underground and in ultra-low background conditions. Long-lived radioisotopes produced by the previous exposure of materials to cosmic rays on the Earth’s surface or even underground can become problematic for the required sensitivity. Here, the studies developed to quantify and reduce the activation yields in detectors and materials used in the set-up of these experiments will be reviewed, considering target materials like germanium, tellurium and xenon together with other ones commonly used like copper, lead, stainless steel or argon. Calculations following very different approaches and measurements from irradiation experiments using beams or directly cosmic rays will be considered for relevant radioisotopes. The effect of cosmogenic activation in present and future double beta decay projects based on different types of detectors will be analyzed too.

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Trace radioactive impurities in final construction materials for EXO-200

Cited by 35 publications

References 20 publications

The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs

The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs

Sensitivity and discovery potential of the proposed nEXO experiment to neutrinoless double- β decay

Cosmogenic Activation in Double Beta Decay Experiments

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