Copper electroplating for background suppression in the NEWS-G experiment

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A90107%2F21%3A00357713" target="_blank" >RIV/68407700:90107/21:00357713 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1016/j.nima.2020.164844" target="_blank" >https://doi.org/10.1016/j.nima.2020.164844</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.nima.2020.164844" target="_blank" >10.1016/j.nima.2020.164844</a>

Result language

angličtina

Original language name

Copper electroplating for background suppression in the NEWS-G experiment

Original language description

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 comprising 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 Po-210 alpha counting method using an XIA detector confirmed a problematic concentration of Pb-210 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-mu m 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 mu Bq/kg (< 0.24 mu Bq/kg) and < 0.26 mu Bq/kg (< 0.11 mu Bq/kg) on the Th-232 and U-238 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 Pb-210 consistent with the background goals of the NEWS-G experiment.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10303 - Particles and field physics

Project

—

Continuities

—

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Nuclear Instruments and Methods in Physics Research, Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

ISSN

0168-9002

e-ISSN

1872-9576

Volume of the periodical

988

Issue of the periodical within the volume

164844

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

7

Pages from-to

1-7

UT code for WoS article

000604693800007

EID of the result in the Scopus database

—