Evolution of collectivity in 72Kr: evidence for rapid shape transition

H Iwasaki; A Lemasson; C Morse; A Dewald; T Braunroth; V M Bader; T Baugher; D Bazin; J S Berryman; C M Campbell; A Gade; C Langer; I Y Lee; C Loelius; E Lunderberg; F Recchia; D Smalley; S R Stroberg; R Wadsworth; C Walz; D Weisshaar; A Westerberg; K Whitmore; K Wimmer

doi:10.1103/PhysRevLett.112.142502

Evolution of collectivity in 72Kr: evidence for rapid shape transition

Phys Rev Lett. 2014 Apr 11;112(14):142502. doi: 10.1103/PhysRevLett.112.142502. Epub 2014 Apr 10.

Authors

H Iwasaki¹, A Lemasson², C Morse¹, A Dewald³, T Braunroth³, V M Bader¹, T Baugher¹, D Bazin², J S Berryman², C M Campbell⁴, A Gade¹, C Langer⁵, I Y Lee⁴, C Loelius¹, E Lunderberg¹, F Recchia², D Smalley², S R Stroberg¹, R Wadsworth⁶, C Walz⁷, D Weisshaar², A Westerberg⁸, K Whitmore¹, K Wimmer⁹

Affiliations

¹ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA.
² National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
³ Institut für Kernphysik der Universität zu Köln, D-50937 Köln, Germany.
⁴ Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
⁵ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA and Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824, USA.
⁶ Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom.
⁷ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA and Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany.
⁸ Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, USA.
⁹ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA and Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, USA.

PMID: 24765947
DOI: 10.1103/PhysRevLett.112.142502

Abstract

The transition rates from the yrast 2+ and 4+ states in the self-conjugate 72Kr nucleus were studied via lifetime measurements employing the GRETINA array with a novel application of the recoil-distance method. The large collectivity observed for the 4+→2+ transition suggests a prolate character of the excited states. The reduced collectivity previously reported for the 2+→0+ transition was confirmed. The irregular behavior of collectivity points to the occurrence of a rapid oblate-prolate shape transition in 72Kr, providing stringent tests for advanced theories to describe the shape coexistence and its evolution.