Back to Search Start Over

First Exploration of Monopole-Driven Shell Evolution above the N=126 Shell Closure: New Millisecond Isomers in ^{213}Tl and ^{215}Tl.

Authors :
Yeung TT
Morales AI
Wu J
Liu M
Yuan C
Nishimura S
Phong VH
Fukuda N
Tain JL
Davinson T
Rykaczewski KP
Yokoyama R
Isobe T
Niikura M
Podolyák Z
Alcalá G
Algora A
Allmond JM
Agramunt J
Appleton C
Baba H
Caballero-Folch R
Calvino F
Carpenter MP
Dillmann I
Estrade A
Gao T
Griffin CJ
Grzywacz RK
Hall O
Hirayama Y
Hue BM
Ideguchi E
Kiss GG
Kokubun K
Kondev FG
Mizuno R
Mukai M
Nepal N
Nurhafiza MN
Ohta S
Orrigo SEA
Pallàs M
Park J
Rasco BC
Rodríguez-García D
Sakurai H
Sexton L
Shimizu Y
Suzuki H
Vitéz-Sveiczer A
Takeda H
Tarifeno-Saldivia A
Tolosa-Delgado A
Victoria JA
Watanabe YX
Yap JM
Source :
Physical review letters [Phys Rev Lett] 2024 Aug 16; Vol. 133 (7), pp. 072501.
Publication Year :
2024

Abstract

Isomer spectroscopy of heavy neutron-rich nuclei beyond the N=126 closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in ^{213}Tl and 874(5) keV in ^{215}Tl. The measured half-lives of 1.34(5) ms in ^{213}Tl and 3.0(3) ms in ^{215}Tl suggest spins and parities 11/2^{-} with the single proton-hole configuration πh_{11/2} as leading component. They are populated via E1 transitions by the decay of higher-lying isomeric states with proposed spin and parity 17/2^{+}, interpreted as arising from a single πs_{1/2} proton hole coupled to the 8^{+} seniority isomer in the ^{A+1}Pb cores. The lowering of the 11/2^{-} states is ascribed to an increase of the πh_{11/2} proton effective single-particle energy as the second νg_{9/2} orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the πh_{11/2} and νg_{9/2} orbitals. The new ms isomers provide the first experimental observation of shell evolution in the almost unexplored N>126 nuclear region below doubly magic ^{208}Pb.

Details

Language :
English
ISSN :
1079-7114
Volume :
133
Issue :
7
Database :
MEDLINE
Journal :
Physical review letters
Publication Type :
Academic Journal
Accession number :
39213556
Full Text :
https://doi.org/10.1103/PhysRevLett.133.072501