Lead-210: a contaminant in particle detectors for dark matter studies

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dc.contributor.authorFroehlich, MBen_AU
dc.contributor.authorMerchel, Sen_AU
dc.contributor.authorSlavkovská, Zen_AU
dc.contributor.authorDastgiri, Fen_AU
dc.contributor.authorFifield, LKen_AU
dc.contributor.authorHotchkis, MACen_AU
dc.contributor.authorKoll, Den_AU
dc.contributor.authorPavetich, Sen_AU
dc.contributor.authorTims, SGen_AU
dc.contributor.authorWallner, Aen_AU
dc.date.accessioned2023-01-20T03:52:14Zen_AU
dc.date.available2023-01-20T03:52:14Zen_AU
dc.date.issued2021-11-17en_AU
dc.date.statistics2022-07-01en_AU
dc.description.abstractThe DAMA/LIBRA (DArk Matter/Large sodium Iodide Block for RAre processes) is a very low background NaI(Tl) detector array that has been running for two decades in the Gran Sasso underground laboratory in Italy. It gives a robust annual modulation signal in the 2 to 6 keV region that may be due to dark matter [1]. In order to verify this result with higher sensitivity, the SABRE (Sodium iodide with Active Background REjection) experiment [2] is being developed. Radioimpurities such as ⁴ ⁰ K, ²³⁸ U, ²¹⁰ Pb and ²³²Th, either intrinsic to the detector material or surface contamination, provide a fundamental limit to the sensitivity of SABRE. Therefore, it is crucial to characterise this background for improved identification of any additional signal above it. Here, we focus on ²¹⁰ Pb (half-life of 22.2 years) as its beta decay to ²¹⁰ Bi contributes to the low-energy “dark matter” spectra [3]. Lead-210 measurements are usually performed using alpha -, beta - or gamma counting depending on the sample size and concentration [4]. However, in recent years, the interest and therefore developments to measure ²¹⁰ Pb using accelerator mass spectrometry (AMS) has increased [5], [6]. From a chemical point of view, we need to optimise the Pb extraction of ~1 mg of stable Pb carrier through precipitations and ion exchange chromatography using about a kilogram of NaI. This is not trivial and methods using two different resins, i.e., 1x8 anion exchange resin and Sr® resin, have been tested. It is also essential that the stable Pb carrier and any material and chemical product in use should contain as little ²¹⁰ Pb as possible. Hence, several materials have been investigated including a piece from a 16th century roof and radiation shielding blocks as a source of Pb carrier. Furthermore, we studied PbO and PbF₂ samples to identify the optimal negative-ion beam and the suitability of using either Fe₂ O₃ or NaF as bulk material for the AMS target to reduce the stable Pb content. AMS measurements related to this work have been made using the 14UD pelletron accelerator at the Australian National University and the 1 MV VEGA accelerator at the Australian Nuclear Science and Technology Organisation.en_AU
dc.identifier.citationFroehlich, M., Merchel, S., Slavkovská, Z., Dastgir, F., Fifield, L. K., Hotchkis, M., Koll. D., Pavetich, S., Tims, S., & Wallner, A. (2021). Lead-210: a contaminant in particle detectors for dark matter studies. Paper presented to the 15th International Conference on Accelerator Mass Spectrometry. ANSTO Sydney, Australia. November 15th – 19th, 2021. (pp. 254). Retrieved from: https://ams15sydney.com/wp-content/uploads/2021/11/AMS-15-Full-Program-and-Abstract-Book-R-1.pdfen_AU
dc.identifier.conferenceenddate19 November 2021en_AU
dc.identifier.conferencename15th International Conference on Accelerator Mass Spectrometryen_AU
dc.identifier.conferenceplaceSydney, Australiaen_AU
dc.identifier.conferencestartdate15 November 2021en_AU
dc.identifier.pagination254en_AU
dc.identifier.urihttps://ams15sydney.com/wp-content/uploads/2021/11/AMS-15-Full-Program-and-Abstract-Book-R-1.pdfen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14453en_AU
dc.language.isoenen_AU
dc.publisherAustralian Nuclear Science and Technology Organisationen_AU
dc.subjectLead 210en_AU
dc.subjectNonluminous matteren_AU
dc.subjectParticlesen_AU
dc.subjectDetectionen_AU
dc.subjectLaboratoriesen_AU
dc.subjectItalyen_AU
dc.subjectkeV range 01-10en_AU
dc.subjectSodium iodidesen_AU
dc.subjectReflectionen_AU
dc.subjectMass spectroscopyen_AU
dc.subjectANSTOen_AU
dc.titleLead-210: a contaminant in particle detectors for dark matter studiesen_AU
dc.typeConference Abstracten_AU
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