First search for resonant enhanced neutrinoless double electron capture in 152Gd and other rare decays in natural Gd isotopes

• Published in: The European physical journal. C, Particles and fields Vol. 83; no. 12; p. 1114
• Main Authors: Laubenstein, M., Lehnert, B., Nagorny, S. S., Nisi, S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 08-12-2023; Springer Nature B.V
• Subjects: Alpha decay; Astronomy; Astrophysics and Cosmology; Beta decay; Daughters; Decay rate; Electron capture; Elementary Particles; Gadolinium; Gadolinium isotopes; Germanium; Hadrons; Half-life; Heavy Ions; Isotopes; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular Article - Experimental Physics; Sensors; String Theory; X-rays
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-023-12218-y

A first search for rare decays of gadolinium isotopes was performed with an ultra-low background high-purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 198 g
Gd
2
O
3
powder sample was measured for 63.8 d with a total Gd exposure of 12.6 kg
×
d.
152
Gd is the most promising isotope for resonant enhanced neutrinoless double electron capture which could significantly increase the decay rate over other neutrinoless double beta decay processes. The half-life for this decay was constrained to
>
4.2
×
10
12
 year (90% credibility). This limit is still orders of magnitude away from theoretical predictions but it is the first established limit on the transition paving the way for future experiments. In addition, other rare alpha and double beta decay modes were investigated in
152
Gd,
154
Gd, and
160
Gd with half-life limits in the range of
10
17
-
20
year.