Microscopic Dynamics of Shape Coexistence Phenomena around 68Se and 72Kr

The adiabatic self-consistent collective coordinate (ASCC) method is applied to the pairing-plus-quadrupole (P + Q) model Hamiltonian including the quadrupole pairing, and the oblate-prolate shape coexistence phenomena in proton-rich nuclei, 68Se and 72Kr,

MICROSCOPICDYNAMICSOFSHAPECOEXISTENCE

PHENOMENAAROUND68SeAND72Kr

NOBUOHINOHARA ,KENICHIMATSUYANAGI

DepartmentofPhysics,GraduateSchoolofScience,KyotoUniversity,

Kyoto606-8502,Japan

E-mail:hinohara@ruby.scphys.kyoto-u.ac.jpTAKASHINAKATSUKASA

TheoreticalNuclearPhysicsLaboratory,RIKENNishinaCenter,

Wako351-0198,JapanMASAYUKIMATSUO

DepartmentofPhysics,FacultyofScience,NiigataUniversity,

Niigata950-2181,Japan

Abstract

Theadiabaticself–consistentcollectivecoordinate(ASCC)methodisappliedtothepairing-plus-quadrupole(P+Q)modelHamiltonianincludingthequadrupolepairing,andtheoblate–prolateshapecoexistencephenomenainproton-richnuclei,68

Seand72Kr,areinvestigated.Itisshownthatthecollectivepathconnectingtheoblateandprolatelocalminimarunsalongatriaxialvalleyinthe(β,γ)plane.QuantumcollectiveHamiltonianisconstructedandlow-lyingenergyspectraandE2transitionprobabilitiesarecalculatedforthe rsttimeusingtheASCCmethod.Basicpropertiesoftheshapecoexistence/mixingarewellreproduced.Wealsoclarifythee ectsofthetime-oddpair eldonthecollectivemass(inertialfunction)forthelarge–amplitudevibrationandontherotationalmomentsofinertiaaboutthreeprincipalaxes.

arXiv:0709.3897v1 [nucl-th] 25 Sep 2007

1Introduction

Inprotonrichnucleiaround68Seand72Kr,oblate–prolateshapecoexistencephenomenaareobserved[1–4].Fromthemean- eldpointofview,theoblateandprolateshapesaremixedbythemany-bodytunnelingthroughthepotentialbarrierbetweenthetwolocalminimainthepotentialenergylandscape.Todescribetheshapemixingdynamics,wehavetodeterminethecollectivedegreesoffreedominwhichdirectionthelarge–amplitudeshapedynamicstakesplace.Theadiabaticself–consistentcollectivecoordi-nate(ASCC)method[5]hasbeenproposedasamicroscopictheoryoflarge–amplitudecollectivemotionsuchastheshapecoexistencephenomena.Thistheoryisbasedonthetime-dependentHartree–Fock–Bogoliubov(TDHFB)theoryandenablesustoextractthecollectivedegreesoffreedominaself–consistentway.Inthepreviouswork[6],wehavesolvedthepairing-plus-quadrupole(P+Q)HamiltonianbymeansoftheASCCmethodfor68Seand72Krnuclei,andsuccessfullyextractedtheone-dimensionalcollec-tivepathconnectingtheoblateandprolatelocalminima.Sincethetwolocalminima

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