The first experimental evidence for the (M1+E2) mixed character of the 9.2 keV transition in Th-227

0549091 - ÚJF 2022 RIV NL eng J - Journal Article
Kovalík, Alojz - Inoyatov, A. K. - Perevoshchikov, L. L. - Ryšavý, Miloš - Filosofov, D. V. - Alexa, P. - Kvasil, J.
The first experimental evidence for the (M1+E2) mixed character of the 9.2 keV transition in Th-227.
Physics Letters. B. Roč. 820, SEP (2021), č. článku 136593. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA MŠMT LTT18021; GA ČR GA19-14048S
Institutional support: RVO:61389005
Keywords : Ac-227 * Th-227 * internal conversion electron spectroscopy * nuclear transition and multipolarity * spin-parity
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 4.950, year: 2021
Method of publishing: Open access
https://doi.org/10.1016/j.physletb.2021.136593

The 9.2 keV nuclear transition in Th-227 was studied in the beta(-)-decay of Ac-227 by means of the internal conversion electron spectroscopy to clarify the spin-parity assignment of the ground state and the two lowest excited states of Th-227. The transition multipolarity was proved to be of mixed character M1+ E2 and the spectroscopic admixture parameter delta(2)(E2/M1) = 0.695 +/- 0.248(vertical bar delta(E2/M1)vertical bar = 0.834 +/- 0.149) was determined. Nonzero value of delta(E2/M1) questioned the present theoretical interpretation of low-lying levels of Th-227. Calculations performed prefer the 1/2(+), 3/2(+), and 3/2(+) sequence instead of the adopted 1/2(+), 5/2(+) and 3/2(+) one for the 0.0, 9.2, and 24.3keV levels, respectively.
Permanent Link: http://hdl.handle.net/11104/0325110