Identification of 210Pb and 210Po in the bulk of copper samples with a low-background alpha particle counter

Abe, K.; Hiraide, K.; Ichimura, Kunihiro; Kishimoto, Y.; Kobayashi, Kazuyoshi; Kobayashi, Masaaki; Moriyama, S.; Nakahata, M.; Norita, T.; Ogawa, Hiroshi; Sato, Katsuhiko; Sekiya, H.; Takachio, O.; Takeda, Atsushi; Tasaka, S.; Yamashita, M.; Yang, B. S.; Kim, Nam Young; Kim, Yeongduk; Itow, Y.; Kanzawa, K.; Kegasa, R.; Masuda, K.; Takiya, H.; Fushimi, K.; Kanzaki, G.; Martens, K.; Suzuki, Yoshihiro; Xu, Benda; Fujita, Ryuichi; Hosokawa, K.; Miuchi, K.; Oka, Naoki; Takeuchi, Y.; Kim, Yong Hamb; Lee, K B; Lee, M K; Fukuda, Y.; Miyasaka, Muneo; Nishijima, K.; Nakamura, Shōgo

doi:10.1016/j.nima.2017.12.015

Cited by 26 publications

(27 citation statements)

References 6 publications

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“…From this fit, it was estimated that the 210 Pb activity in the sample is 29 +8+9 −8−3 mBq kg −1 , where the statistical and systematic uncertainties are given seperately. This is consistent with other copper samples with similar purity [20].…”

Section: Assessment Of the 210 Pb Contamination In News-g Coppersupporting

confidence: 92%

“…This improves the signal-to-noise ratio for selecting bulk α particle events. The conversion factor for measured counts to bulk activity was estimated from Geant4 to be 2.7 × 10 2 (Bq/kg)/(α/cm 2 /hour) [20].…”

Section: Assessment Of the 210 Pb Contamination In News-g Coppermentioning

confidence: 99%

“…The progeny activities can also be inferred and used to estimate background contributions to experiments, under the assumption of secular equilibrium. [20]. For oxygen-free copper (at least 99.96% pure by weight 3 ) the 210 Pb contamination is estimated to be in the range of 17-40 mBq/kg [20].…”

Section: Introductionmentioning

confidence: 99%

“…[20]. For oxygen-free copper (at least 99.96% pure by weight 3 ) the 210 Pb contamination is estimated to be in the range of 17-40 mBq/kg [20].…”

Section: Introductionmentioning

confidence: 99%

“…A method to deposit ultra-radiopure copper is potentiostatic electroforming [20,23]. This method takes advantage of electrochemical properties to produce copper with reduced impurities.…”

Section: Introductionmentioning

confidence: 99%

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Copper electroplating for background suppression in the NEWS-G experiment

Balogh¹,

Beaufort²,

Brossard³

et al. 2020

Preprint

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New Experiments with Spheres-Gas (NEWS-G) is a dark matter direct detection experiment that will operate at SNOLAB (Canada). Similar to other rare-event searches, the materials used in the detector construction are subject to stringent radiopurity requirements. The detector features a 140-cm diameter proportional counter comprised of two hemispheres made from commercially sourced 99.99% pure copper. Such copper is widely used in rare-event searches because it is readily available, there are no long-lived Cu radioisotopes, and levels of non-Cu radiocontaminants are generally low. However, measurements performed with a dedicated 210 Po alpha counting method using an XIA detector confirmed a problematic concentration of 210 Pb in bulk of the copper. To shield the proportional counter's active volume, a low-background electroforming method was adapted to the hemispherical shape to grow a 500-µm thick layer of ultra-radiopure copper to the detector's inner surface. In this paper the process is described, which was prototyped at Pacific Northwest National Laboratory (PNNL), USA, and then conducted at full scale in the Laboratoire Souterrain de Modane in France. The radiopurity of the electroplated copper was assessed through inductively coupled plasma mass spectrometry (ICP-MS). Measurements of samples from the first (second) hemisphere give 68% confidence upper limits of <0.58 µBq/kg (<0.24 µBq/kg) and <0.26 µBq/kg (<0.11 µBq/kg) on the 232 Th and 238 U contamination levels, respectively. These results are comparable to previously reported measurements of electroformed copper produced for other rare-event searches, which were also found to have low concentration of 210 Pb consistent with the background goals of the NEWS-G experiment.

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Section: Assessment Of the 210 Pb Contamination In News-g Coppersupporting

confidence: 92%

Section: Assessment Of the 210 Pb Contamination In News-g Coppermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[20]. For oxygen-free copper (at least 99.96% pure by weight 3 ) the 210 Pb contamination is estimated to be in the range of 17-40 mBq/kg [20].…”

Section: Introductionmentioning

confidence: 99%

“…A method to deposit ultra-radiopure copper is potentiostatic electroforming [20,23]. This method takes advantage of electrochemical properties to produce copper with reduced impurities.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Copper electroplating for background suppression in the NEWS-G experiment

Balogh¹,

Beaufort²,

Brossard³

et al. 2020

Preprint

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Initial performance of the high sensitivity alpha particle detector at the Yangyang underground laboratory

Adhikari

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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Initial performance of the UltraLo-1800 alpha particle detector at the 700 m deep Yangyang underground laboratory in Korea is described. The ionization detector uses Argon as a counting gas for measuring alpha events of a sample. We present initial calibration results and low-activity sample measurements based on the detector's pulse discrimination method and a hardware veto. A likelihood analysis that shows a separation of a bulk component from a surface component with a contamination depth from 210 Po alpha particles using simulated models is presented.

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Development of spherical proportional counter for light WIMP search within NEWS-G collaboration

Dastgheibi-Fard¹,

Geribier²

2020

Nuclear Instruments and Methods in Physics Research Section A:

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The Spherical gaseous detector (or Spherical Proportional Counter, SPC) has a broad range of applications. In this work, we will focus on the light WIMP Dark Matter particle search, that is, below a few GeV. The NEWS-G collaboration operates a 60 cm diameter detector at Modane underground laboratory (LSM). Running the detector at 3 bars of Neon gas, some competitive limits have been set down to 0.5 GeV WIMP mass thanks to an energy threshold of around 100 eV. To reach better performances, the next generation of SPC (140cm), NEWS-G SNO, is under construction. We will focus here on the fabrication method, the different low energy calibration methods using 37 Ar, neutron and UV laser, on the cleaning methods to remove the surface contamination and mitigation of 210 Pb bulk contamination.

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Identification of 210Pb and 210Po in the bulk of copper samples with a low-background alpha particle counter

Cited by 26 publications

References 6 publications

Copper electroplating for background suppression in the NEWS-G experiment

Copper electroplating for background suppression in the NEWS-G experiment

Initial performance of the high sensitivity alpha particle detector at the Yangyang underground laboratory

Development of spherical proportional counter for light WIMP search within NEWS-G collaboration

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