First direct search for 2ε and εβ+ decay of 144Sm and 2β- decay of 154Sm

• Published in: The European physical journal. A, Hadrons and nuclei Vol. 55; no. 11
• Main Authors: Belli, P., Bernabei, R., Boiko, R. S., Cappella, F., Caracciolo, V., Cerulli, R., Danevich, F. A., Di Marco, A., Incicchitti, A., Kropivyansky, B. N., Laubenstein, M., Nisi, S., Poda, D. V., Polischuk, O. G., Tretyak, V. I.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2019
• Subjects: Hadrons; Heavy Ions; Nuclear Fusion; Nuclear Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Regular Article - Experimental Physics
• ISSN: 1434-6001; 1434-601X
• DOI: 10.1140/epja/i2019-12911-3

. The first direct search for the double electron capture ( 2 ε ) and the electron capture with positron emission ( ε β + ) in 144 Sm to the ground state and to the excited levels of 144 Nd was realized by measuring --over 1899h-- a 342g sample of highly purified samarium oxide (Sm 2 O 3 ) with the ultra-low background HP-Ge γ spectrometer GeCris (465cm 3 ) at the STELLA facility of the Gran Sasso National Laboratory (LNGS). No effect was observed and half-life limits were estimated at the level of T 1 / 2 ∼ ( 0 . 1 - 1 . 3 ) × 10 20 yr (90% C.L.). Moreover, for the first time half-life limits of the double beta ( 2 β - ) decay of 154 Sm to several excited levels of 154 Gd have been set; they are at the level of T 1 / 2 ∼ ( 0 . 06 - 8 ) × 10 20 yr (90% C.L.).