High-spin states in ,[object Object],Po above the ,[object Object],-decaying (18 ,[object Object],) isomer
L. Zago (Dipartimento di Fisica dell'Università degli Studi di Padova, Padova, 35131, Italy, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, 35020, Italy)
; A. Gottardo (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, 35020, Italy); J.J. Valiente-Dobón (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, 35020, Italy); G. Benzoni (Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Milano, 20133, Italy); A. Gadea (Instituto de Física Corpuscular, CSIC-Universitat de València, València, 46980, Spain); et al - Show all 61 authors
The nucleus 212Po has been produced through the fragmentation of a 238U primary beam at 1 GeV/nucleon at GSI, separated with the FRagment Separator, FRS, and studied via isomer γ-decay spectroscopy with the RISING setup. Two delayed previously unknown γ rays have been observed. One has been attributed to the E3 decay of a 21 − isomeric state feeding the α-emitting 45-s (18 +) high-spin isomer. The other γ-ray line has been assigned to the decay of a higher-lying 23 + metastable state. These are the first observations of high-spin states above the 212Po (18 +) isomer, by virtue of the selectivity obtained via ion-by-ion identification of 238U fragmentation products. Comparison with shell-model calculations points to shortfalls in the nuclear interactions involving high- j proton and neutron orbitals, to which the region around Z∼100 is sensitive.
