Analysis of radioactive trace impurities with μBq-sensitivity in Borexino

Simgen, H.; Heusser, G.; Laubenstein, M.; Zuzel, G.

doi:10.1142/s0217751x14420093

Cited by 12 publications

(9 citation statements)

References 21 publications

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“…Hence, a further 222 Rn reduction by cleaning attempts was not measurable within our sensitivity. Again it was confirmed that stainless steel TIG-welds do not represent a notable additional source of 222 Rn, which is in tension with findings from other experiments [14,20].…”

Section: Stainless Steelsupporting

confidence: 64%

$$^{222}$$Rn emanation measurements for the XENON1T experiment

Aprile¹,

Aalbers²,

Agostini³

et al. 2021

Eur. Phys. J. C

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The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the $$^{222}$$ 222 Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a $$^{222}$$ 222 Rn activity concentration of $$10\,\mathrm{\,}\upmu \mathrm{Bq}/\mathrm{kg}$$ 10 μ Bq / kg in $$3.2\,\mathrm{t}$$ 3.2 t of xenon. The knowledge of the distribution of the $$^{222}$$ 222 Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the $$^{222}$$ 222 Rn activity concentration in XENON1T. The final $$^{222}$$ 222 Rn activity concentration of $$(4.5\pm 0.1)\,\mathrm{\,}\upmu \mathrm{Bq}/\mathrm{kg}$$ ( 4.5 ± 0.1 ) μ Bq / kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.

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Section: Stainless Steelsupporting

confidence: 64%

$$^{222}$$Rn emanation measurements for the XENON1T experiment

Aprile¹,

Aalbers²,

Agostini³

et al. 2021

Eur. Phys. J. C

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“…• the realization of the CTF; 17 • the purification of liquid scintillation, water and Nitrogen; 18,23,25 • selecting the materials concerning the ID and the OD, nylon, PMTs, and plant components and installations; 19,21,22 • the assembling of the nylon vessels and the installation of the detector and its subsystems; 20 • the procedures for the pseudocumene procurement and the detector filling; 24,27 • the detector calibration; 26 • the data analysis. 28 …”

mentioning

confidence: 99%

Technologies of the Borexino experiment: Introduction

Bellini

2014

Int. J. Mod. Phys. A

158

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At the beginning of 1990 a discussion started among physicists at Bell Lab, Milano University and INFN on the possibility to design a detector to measure the solar neutrinos at low energy, say below ∼ 2 MeV: the goal at the beginning was, first of all, the measurement of the neutrino flux from 7 Be at 0.867 MeV.At that time solar neutrinos were studied by the radiochemical experiments, such as Homestake, GALLEX and Sage. At the same time the Cherenkov detectors were either running or in preparation.The radiochemical experiments were able to measure only an integrated neutrino flux from a lower threshold: 0.814 MeV for Homestake and 0.233 MeV for GALLEX, but not the single fluxes produced by the various reactions expected to be the source of the Sun shining. The real time Cherenkov experiments faced a high background due to the decay products of the natural radioactive contaminants from the construction materials and the environment, which reach an upper energy limit of ∼ 3 MeV (Tallium nuclides); energy thresholds at relatively high energy as ∼ 7 MeV or ∼ 5 MeV have been the solution adopted by these experiments. Only later some attempts have been done to lower the thresholds, which, however, did not allow to measure flows other than the high energy tail of the 8 B neutrinos.For the solar neutrinos, the lower is the neutrino energy, the higher is the neutrino flux. The pp reaction produces by far the highest rate, while the direct daughter reaction involving 7 Be is the second solar neutrino producer. The 8 B tile measured by the Cherenkov experiments contributes a ∼ 0.01% to the total solar neutrinos.The new detector has been conceived to have high resolution and an unprecedented radio-purity. These constraints suggested to choose as detecting material a liquid scintillator and to develop an R&D, which lasted four years, to develop 1402002-1 Int. J. Mod. Phys. A 2014.29. Downloaded from www.worldscientific.com by UNIVERSITY OF PITTSBURGH on 06/25/14. For personal use only. 1402002-2 Int. J. Mod. Phys. A 2014.29. Downloaded from www.worldscientific.com by UNIVERSITY OF PITTSBURGH on 06/25/14. For personal use only.

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“…Testing HPN and RPN it turned out that they do not fulfill the above specifications therefore we worked on a suitable purification method and in parallel searched also on the marked for enough pure gas. Results obtained for nitrogen from different European suppliers and of different qualities are summarized in Table 3 [24]. In most cases the requirement for argon was met.…”

Section: Purification Of Nitrogenmentioning

confidence: 99%

“…Argon and krypton concentrations were always within the specifications [24]. HPN 2 was also used to produce synthetic air needed for the inflation of the inner vessel and the radon barrier balloons.…”

Section: Purification Of Nitrogenmentioning

confidence: 99%

“…Synthetic air was produced by mixing HPN 2 with oxygen from gas cylinders (selected earlier with respect to 222 Rn emanation). Taking into account the measured emanation rate from the used bottle package and from the mixer we estimated the 222 Rn content in the air to be less than 100 µBq/m 3 (radio-purest air ever available) [24].…”

Section: Purification Of Nitrogenmentioning

confidence: 99%

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