Search for particle–vibration coupling in 65Cu

The lifetime of the 9/2 + state of 65 Cu, at 2534 keV, has been measured by fast timing techniques, in order to establish wether such state arises from a weak coupling between a p3=2 proton and the 3 octupole vibration at 3.56 MeV in the 64 Ni core. The 65 Cu nucleus was populated by the reaction 7 Li + 64 Ni at 32 MeV, at the Horia Hu- lubei National Institute of Physics and Nuclear Engineering (NIPNE) in Bucharest, and its -decay was detected by the ROSPHERE array. The measured lifetime coresponds to a B(E3) reduced transition probability to the ground state equal to 8.89 W.u., in agreement with theoretical predictions in the weak coupling limit

Spectroscopy of odd-mass cobalt isotopes toward the N=40 subshell closure and shell-model description of spherical and deformed states

The neutron-rich cobalt isotopes up to A = 67 have been studied through multinucleon transfer reactions by bombarding a 238U target with a 460-MeV 70Zn beam. Unambiguous identification of prompt γ rays belonging to each nucleus has been achieved using coincidence relationships with the ions detected in a high-acceptance magnetic spectrometer. The new data are discussed in terms of the systematics of the cobalt isotopes and interpreted with large-scale shell-model calculations in the fpgd model space. In particular, very different shapes can be described in 67Co, at the edge of the island of inversion at N = 40, where a low-lying highly deformed band coexists with a spherical structureThis work was partially supported by the European Community FP6, Structuring the ERA Integrated Infrastructure Initiative Contract No. EURONS RII3-CT-2004-506065, by MICINN, Spain (Contract No. FPA2011-29854), by IN2P3, France (Contract No. AIC-D-2011-648), by Comunidad de Madrid, Spain (Contract No. HEPHACOS S2009-ESP-1473), and by Generalitat Valenciana, Spain (Contract No. PROMETEO/ 2010/101). A. Gadea and E. Farnea acknowledge the support of MICINN, Spain, and INFN, Italy, through the AIC-D-2011-0746 bilateral actio

Fast-timing study of the l -forbidden 12+→32+ M1 transition in Sn 129 FAST-TIMING STUDY of the l -FORBIDDEN ⋯ R. LICǎ et al.

© 2016 authors. Published by the American Physical Society.The levels in Sn129 populated from the β- decay of In129 isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 12+ state and the 32+ ground state in Sn129 are expected to have configurations dominated by the neutron s12 (l=0) and d32 (l=2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l-forbidden M1 transition. Using fast-timing spectroscopy we have measured the half-life of the 12+ 315.3-keV state, T12= 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T12 value by the renormalization of the M1 effective operator for neutron holes

First in-beam γ -ray study of the level structure of neutron-rich S 39

International audienceThe neutron-rich S39 nucleus has been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of S36 ions with a thin Pb208 target. The magnetic spectrometer, PRISMA, and the γ-ray array, CLARA, were used in the measurements. Gamma-ray transitions of the following energies were observed: 339, 398, 466, 705, 1517, 1656, and 1724 keV. Five of the observed transitions have been tentatively assigned to the decay of excited states with spins up to (11/2−). The results of a state-of-the-art shell-model calculation of the level scheme of S39 using the SDPF-U effective interaction are also presented. The systematic behavior of the excitation energy of the first 11/2− states in the odd-A isotopes of sulfur and argon is discussed in relation to the excitation energy of the first excited 2+ states of the adjacent even-A isotopes. The states of S39 that have the components in their wave functions corresponding to three neutrons in the 1f7/2 orbital outside the N=20 core have also been discussed within the context of the 0 ℏω shell-model calculations presented here

Proton-hole states in the N=30 neutron-rich isotope K49

Excited states in the N=30 neutron-rich isotope K49 have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target γ-coincidence data from Gammasphere. The d3/2 proton-hole state is located 92 keV above the s1/2 ground state, and the proton-particle f7/2 state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2+ of two neutrons above the N=28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure, which is found to be in satisfactory agreement with shell-model calculations

Search for particle–vibration coupling in 65Cu

The lifetime of the 9/2+ state of 65Cu, at 2534 keV, has been measured by fast timing techniques, in order to establish wether such state arises from a weak coupling between a p3/2 proton and the 3− octupole vibration at 3.56 MeV in the 64Ni core. The 65Cu nucleus was populated by the reaction 7Li + 64Ni at 32 MeV, at the Horia Hulubei National Institute of Physics and Nuclear Engineering (NIPNE) in Bucharest, and its γ-decay was detected by the ROSPHERE array. The measured lifetime coresponds to a B(E3) reduced transition probability to the ground state equal to 8.89 W.u., in agreement with theoretical predictions in the weak coupling limit

Nanosecond lifetime measurements of Iπ¼9/2- intrinsic excited states and low-lying B(E1)strengths in 183Re using combined HPGe-LaBr3 coincidence spectroscopy

This paper presents precision measurements of electromagnetic decay probabilities associated with electric dipole transitions in the prolate-deformed nucleus 183Re. The nucleus of interest was formed using the fusion evaporation reaction 180Hf(7Li,4n)183Re at a beam energy of 30 MeV at the tandem accelerator at the HH-IFIN Institute, Bucharest Romania. Coincident decay gamma rays from near-yrast cascades were detected using the combined HPGe-LaBr3 detector array ROSPHERE. The time differences between cascade gamma rays were measured using the LaBr3 detectors to determine the half-lives of the two lowest lying spin-parity 9/2- states at excitation energies of 496 and 617 keV to be 5.65(5) and 2.08(3) ns respectively. The deduced E1 transition rates from these two states are discussed in terms of the K-hindrance between the low-lying structures in this prolate-deformed nucleus

Nanosecond lifetime measurements of Iπ¼9/2- intrinsic excited states and low-lying B(E1)strengths in 183Re using combined HPGe-LaBr3 coincidence spectroscopy

This paper presents precision measurements of electromagnetic decay probabilities associated with electric dipole transitions in the prolate-deformed nucleus 183Re. The nucleus of interest was formed using the fusion evaporation reaction 180Hf(7Li,4n)183Re at a beam energy of 30 MeV at the tandem accelerator at the HH-IFIN Institute, Bucharest Romania. Coincident decay gamma rays from near-yrast cascades were detected using the combined HPGe-LaBr3 detector array ROSPHERE. The time differences between cascade gamma rays were measured using the LaBr3 detectors to determine the half-lives of the two lowest lying spin-parity 9/2- states at excitation energies of 496 and 617 keV to be 5.65(5) and 2.08(3) ns respectively. The deduced E1 transition rates from these two states are discussed in terms of the K-hindrance between the low-lying structures in this prolate-deformed nucleus

Evolution of nuclear structure in the neutron-rich ^96,97,99Nb isotopes:evidence for shape coexistence in N=58 ⁹⁹Nb

Excited states of the neutron-rich niobium isotopes 96,97,98,9941Nb have been populated in two experiments which used fusion-fission and multinucleon binary grazing reactions to populate high-spin yrast states. In the multinucleon-transfer experiment, a 530-MeV beam of 96Zr ions was incident on a thin 124Sn target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and the associated rays were detected using the CLARA array of Ge detectors. In the second experiment, the GASP array of escape-suppressed Ge detectors was used to detect rays from fusion-fission products formed following the interaction of a 230-MeV beam of 36S ions with a thick target of 176Yb . Level schemes of 96,97,99Nb were established up to excitation energies of 4545, 5409, and 3814 keV, respectively; states with proposed spin values up to about 15 ℏ were populated. Gamma-ray photopeaks corresponding to transitions in 98Nb were also observed in the PRISMA-CLARA experiment; however, it was not possible, in this case, to produce a level scheme based on -ray coincidence data from the GASP experiment. For 96Nb and 97Nb , the level schemes are in agreement with the results of earlier publications. Two new decay sequences have been populated in 99Nb ; tentative values of the hitherto unobserved states have been assigned through comparisons with values of neighboring nuclei. In contrast with earlier published studies of the high-spin spectroscopy of 96Nb and 97Nb , the present work provides an unambiguous association of the observed rays with the and of the excited nucleus. The structure of the yrast states of 96,97,99Nb is discussed within the context of shell-model calculations. The experimental results, supported by model calculations, indicate the first observation of shape coexistence at low spin and low excitation energy in the =58 nucleus 99Nb . The results of TRS calculations indicate that the 9/2+ ground state is triaxial, tending to oblate shapes with a transition to a more deformed prolate shape beyond the 17/2+ member of the decay sequence; here the sequence has been observed to (29/2+). On the other hand, the previously unobserved decay sequence based on the 5/2− state at 631 keV exhibits the characteristics of a rotational sequence and has been assigned Nilsson quantum numbers 5/2−⁢[303]. TRS calculations indicate that the 5/2−⁢[303] band is gamma soft and this is consistent with the inability of the particle-rotor model to reproduce the observed behavior of the signature-splitting function

Spectroscopy of neutron-rich 59-63Mn isotopes

none43The neutron-rich Mn isotopes from A=59 to 63 have been studied through multi-nucleon transfer reactions by bombarding a 238U target with a beam of 70Zn at an energy of Elab=460 MeV. Prompt γ rays measured by the CLARA array have been identified unambiguously for each nucleus, using coincidence relationships with ions detected in the high-acceptance magnetic spectrometer PRISMA. The new data extends the knowledge of the low-lying level structure of Mn isotopes, which is discussed in terms of the systematics of the region. Results are compared with large-scale shell-model calculations using different effective interactions and valence spaces.noneJ.J.VALIENTE-DOBON; S.M.LENZI; S.J.FREEMAN; LUNARDI S.; J.F.SMITH; A.GOTTARDO; F.DELLA VEDOVA; E.FARNEA; A.GADEA; D.R.NAPOLI; M.AXIOTIS; S.AYDIN; D.BAZZACCO; P.G.BIZZETI; A.M.BIZZETI-SONA; G.BENZONI; D.BUCURESCU; L.CORRADI; A.N.DEACON; G.DE ANGELIS; E.FIORETTO; B.GUIOT; M.IONESCU-BUJOR; A.IORDACHESCU; S.LEONI; N.MARGINEAN; R.MARGINEAN; P.MASON; R.MENEGAZZO; D.MENGONI; B.MILLION; G.MONTAGNOLI; R.ORLANDI; F.RECCHIA; E.SAHIN; F.SCARLASSARA; R.P.SINGH; A.M.STEFANINI; D.STEPPENBECK; S.SZILNER; C.A.UR; B.J.VARLEY; O.WIELANDJ. J., VALIENTE DOBON; Lenzi, SILVIA MONICA; S. J., Freeman; Lunardi, Santo; J. F., Smith; Gottardo, Andrea; F., DELLA VEDOVA; E., Farnea; A., Gadea; D. R., Napoli; M., Axiotis; S., Aydin; D., Bazzacco; P. G., Bizzeti; A. M., BIZZETI SONA; G., Benzoni; D., Bucurescu; L., Corradi; A. N., Deacon; G., DE ANGELIS; E., Fioretto; B., Guiot; M., IONESCU BUJOR; A., Iordachescu; S., Leoni; N., Marginean; R., Marginean; P., Mason; R., Menegazzo; Mengoni, Daniele; B., Million; Montagnoli, Giovanna; R., Orlandi; Recchia, Francesco; E., Sahin; Scarlassara, Fernando; R. P., Singh; A. M., Stefanini; D., Steppenbeck; S., Szilner; C. A., Ur; B. J., Varley; O., Wielan