A1 Journal article (refereed)
Observation of the 𝐽≤7/2 low-spin states in 213Fr populated in the electron capture of the 1/2− ground state of 213Ra (2024)

Clisu, C., Andreyev, A. N., Nita, C. R., Lica, R., Naïdja, H., Andel, B., Antalic, S., Berry, T. A., Borge, M. J. G., Cocolios, T. E., Costache, C., Cubiss, J. G., De Witte, H., Fraile, L. M., Fynbo, H., Gadelshin, V. M., Granados, C., Greenlees, P., Heinke, R., Huyse, M., Lazarus, I., Leimbach, D., Marginean, N., Marginean, R., Marsh, B. A., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ovejas, J. D., Page, R. D., Pascu, S., Perea, A., Podolyak, Zs., Pucknell, V., Rahkila, P., Rezynkina, K., Rossel, R. E., Sotty, C. O., Stan, L., Studer, D., Tengblad, O., Van Duppen, P., Vedia, V., Warr, N., The IDS Collaboration. (2024). Observation of the 𝐽≤7/2 low-spin states in 213Fr populated in the electron capture of the 1/2− ground state of 213Ra. Physical Review C, 110, Article 064315. https://doi.org/10.1103/physrevc.110.064315

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Publication details

All authors or editors: Clisu, C.; Andreyev, A. N.; Nita, C. R.; Lica, R.; Naïdja, H.; Andel, B.; Antalic, S.; Berry, T. A.; Borge, M. J. G.; Cocolios, T. E.; et al.

Journal or series: Physical Review C

ISSN: 2469-9985

eISSN: 2469-9993

Publication year: 2024

Publication date: 16/12/2024

Volume: 110

Article number: 064315

Publisher: American Physical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/physrevc.110.064315

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/99052

Abstract

A detailed level scheme of 21 Fr126 following the EC/𝛽+ decay of the 1/2− 213Ra parent ground state was built in an experiment performed at the ISOLDE Decay Station, CERN. The fragmented total 𝛽 decay strength favours the direct population of several low-spin (𝐽≤7/2) excited states. The analysis of the 𝛾-singles spectrum and 𝛾−𝛾 coincidences allowed us to identify many new 𝛾-ray transitions and excited states in 213Fr up to about 3.6 Me Vexcitation energy. The spins and parities of the newly established levels, on top of the (7/2−1) state, were mainly assigned based on the systematics of the 𝑁=126 isotones and further compared with shell-model calculations. The level scheme displays a structural pattern, with several groups of states with negative parity, emerging from the well defined, simple, 𝜋⁡(ℎ59/2), 𝜋⁡(ℎ49/2⁡𝑓17/2) configurations or from their configuration mixing. The strength of the E2 transitions within the multiplets is compared with shell-model theoretical calculations performed with the KHPE and H208 effective interactions. A new (3/2−) isomer with a half-life of 26(3) ns has been identified. An upper limit of 35 ps was determined for the half-life of the first excited state, 7/2−. The possibility of a mixed 𝑀⁢1 +𝐸⁢2 character is discussed for the 7/2−1→9/2−gs decay in 213Fr, which leads to an 𝑙-forbidden nature of the 𝜋⁢𝑓7/2→𝜋⁢ℎ9/2 transition.

Keywords: particle physics; nuclear physics

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