Improved sensitivity in the search for rare decays of Gd isotopes
Abstract Gadolinium is widely used in multiple low-background experiments, making its isotopes accessible for rare decay searches both in-situ and through radiopurity screening data. This study presents an improved search for rare alpha and double-beta decay modes in $$^{152}\hbox {Gd}$$ 152 Gd , $$...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-06-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | https://doi.org/10.1140/epjc/s10052-025-14348-x |
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| Summary: | Abstract Gadolinium is widely used in multiple low-background experiments, making its isotopes accessible for rare decay searches both in-situ and through radiopurity screening data. This study presents an improved search for rare alpha and double-beta decay modes in $$^{152}\hbox {Gd}$$ 152 Gd , $$^{154}\hbox {Gd}$$ 154 Gd , and $$^{160}\hbox {Gd}$$ 160 Gd isotopes using ultra-low background HPGe detectors at the Boulby Underground Screening (BUGS) facility. A total exposure of 6.7 $$\hbox {kg}\cdot \hbox {years}$$ kg · years of natural gadolinium was achieved using gadolinium sulfate octahydrate $$(\text {Gd}_2(\text {SO}_4)_3 \cdot 8\text {H}_2\text {O})$$ ( Gd 2 ( SO 4 ) 3 · 8 H 2 O ) samples, originally screened for radiopurity prior to their deployment in the Super-Kamiokande neutrino experiment. Due to the detection methodology, only decays into excited states accompanied by gamma-ray emission were accessible. A Bayesian analysis incorporating prior experimental results was employed, leading to new lower half-life limits in the range of $$10^{19} - 10^{21}$$ 10 19 - 10 21 years - an improvement of approximately two orders of magnitude over previous constraints. No statistically significant decay signals were observed. These results demonstrate the effectiveness of repurposing large-scale radiopurity screening campaigns for fundamental physics research. |
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| ISSN: | 1434-6052 |