Half-life measurements in 164,166Dy using γ-γ fast-timing spectroscopy with the ν-Ball spectrometer

We report on the measurement of lifetimes of excited states in the near-mid-shell nuclei 164,166Dy using the gamma-ray coincidence fast-timing method. The nuclei of interest were populated using reactions between an 18O beam and a gold-backed isotopically enriched 164Dy target of thickness 6.3 mg/cm2 at primary beam energies of 71, 76, and 80 MeV from the IPN-Orsay laboratory, France. Excited states were populated in 164Dy, 166Dy, and 178,179Wfollowing Coulomb excitation, inelastic nuclear scattering, two-neutron transfer, and fusion-evaporation reaction channels respectively. Gamma rays from excited states were measured using the ν-Ball high-purity germanium (HPGe)-LaBr3 hybrid γ -ray spectrometer with the excited state lifetimes extracted using the fast-timing coincidence method using HPGe-gated LaBr3-LaBr3 triple coincident events. The lifetime of the first Iπ = 2+ excited state in 166Dy was used to determine the transition quadrupole deformation of this neutron-rich nucleus for the first time. The experimental methodology was validated by showing consistency with previously determined excited state lifetimes in 164Dy. The half-lives of the yrast 2+ states in 164Dy and 166Dy were 2.35(6) and 2.3(2) ns, respectively, corresponding to transition quadrupole moment values of Q0 = 7.58(9) and 7.5(4) eb, respectively. The lifetime of the yrast 2+ state in 166Dy is consistent with a quenching of nuclear quadrupole deformation at β ≈ 0.35 as the N = 104 mid-shell is approached.

CANAVAN Rhiann;  RUDIGIER Matthias;  REGAN P. H;  LEBOIS M.;  WILSON J. N.;  JOVANCEVIC Nikola;  SÖDERSTRÖM P.A.;  COLLINS S. M.;  THISSE D.;  BENITO J.;  BOTTONI S.;  BRUNET M.;  CIEPLICKA-ORYNCZAK N.;  COURTIN S.;  DOHERTY D.T.;  FRAILE L.M.;  HADYNSKA-KLEK K.;  HAEFNER G.;  HEINE M.;  ISKRA L.W.;  KARAYONCHEV V.;  KENNINGTON A.;  KOSEOGLOU P.;  LOTAY G.;  LORUSSO G.;  NAKHOSTIN M.;  NITA C.;  OBERSTEDT Stephan;  PODOLYAK Z.;  QI Liqiang;  REGIS J.M.;  SANCHEZ-TEMBLEQUE V.;  SHEARMAN R.;  VEDIA V.;  WITT W.; 

2020-04-29

AMER PHYSICAL SOC

JRC120466

2469-9985 (online),   

https://publications.jrc.ec.europa.eu/repository/handle/JRC120466,   

10.1103/PhysRevC.101.024313 (online),