Reduced hindrance factors for K-forbidden E2 transitions from two- and three-quasiparticle isomers in the Aapprox =180 deformed region are compared. Evidence is presented that when all three quasiparticles are of the same nucleon type (proton or neutron) there is a strong dependence of the E2 reduced hindrance factor on the isomer ...

Targets of {sup 48}Ca have been bombarded with {sup 134,136}Xe beams as part of a search for long-lived, high-K states in well-deformed nuclei with A(approx =)180. Several known isomers were observed by off-line {gamma}-ray detection, and limits have been established for high-K isomer production in various isotopes of hafnium (A=175-178), tantalum (A=177-181), and tungsten (A=177-181). (c) 2000 ...

The matrix coherent-state approach of the interacting boson model with configuration mixing is used to study the geometry of the platinum isotopes. With a parameter set determined in previous studies, it is found that the absolute minimum of the potential for the Pt isotopes evolves from spherical to oblate and finally to prolate shapes when the neutron number decreases from N=126 (semi-magic) to ...

A series of recoil distance Doppler-shift lifetime measurements have been carried out to probe collectivity and configuration mixing of different shapes in the vicinity of neutron mid-shell Pb nuclei. Lifetime measurements of {sup 186}Pb and {sup 194}Po, the first ever utilizing the recoil-decay tagging method, probed the collectivity of coexisting prolate and oblate shapes in ...

A series of recoil distance Doppler-shift lifetime measurements have been carried out to probe collectivity and configuration mixing of different shapes in the vicinity of neutron mid-shell Pb nuclei. Lifetime measurements of 186Pb and 194Po, the first ever utilizing the recoil-decay tagging method, probed the collectivity of coexisting prolate and oblate shapes in this ...

?-particle evaporation energy spectra have been measured as a function of ?-ray fold for various target-projectile systems leading to residual nuclei in the range of Z~70 and A~180 with excitation energy of 30-40 MeV. The inverse level-density parameter K was determined for various nuclei by comparing the high-energy part of the ?-particle evaporation spectra with PACE2 predictions. It is observed ...

With new high statistic data, new isotopes and new high-spin structures are observed in neutron-rich nuclei populated in the spontaneous fission of 252Cf. The 135Te levels are extended, and many new levels in 139,141Ba observed. The coexistence of collective and single particle-hole states is found in 135Te. The N = 83 135Te and 139Ba show marked differences associated with differences in their ...

For the first time, non-yrast structures of the neutron mid-shell nucleus {sup 186}Pb have been identified in an in-beam {gamma}-ray spectroscopy measurement using the recoil-decay tagging technique. The yrast band has been tentatively extended up to I{sup {pi}}=20{sup +}, revealing a similar backbend to that observed in the Pt and Hg isotones. Three new bands and several ...

Intruder state excitation energies in odd-mass nuclei just outside a closed proton shell plotted versus neutron number generally exhibit parabola-shaped curves with minima near neutron mid-shells. The Bi isotopes, however, do not seem to follow this trend...

The changes of the mean-square charge radii have been measured for198Pt-183Pt by means of resonance ionization mass spectroscopy (RIMS) at the new on-line isotope separator ISOLDE-3/CERN. As in the case of the neighbouring isotopes of Au and Hg, a strong nuclear deformation of �?2� ?-0.24 is reached at the neutron mid-shell nucleus183Pt, but no indication for a sharp shape ...

Precise measurements of the lifetimes of the first excited 2+ states in the stable even-A Sn isotopes 112�124Sn have been performed using the Doppler shift attenuation technique. For the isotopes 112Sn, 114Sn and 116Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously reported values and indicate a shallow minimum at N=66. The observed ...

Detailed fine-structure ?-decay studies of 188,190Bi were performed using the complete-fusion reactions of 50,52Cr ions with a 142Nd target at the velocity filter SHIP. The evaporation residues were separated in-flight and subsequently identified on the basis of recoil-?, recoil-?-?/X-ray and excitation function measurements. Improved data on the ?-decay of 188,190Bi were obtained and a number of ...

The new neutron-deficient isotope {sup 187}Po has been identified in the complete fusion reaction {sup 46}Ti+{sup 144}Sm{yields}{sup 187}Po+3n at the velocity filter SHIP. Striking features of the {sup 187}Po {alpha} decay are the strongly-hindered decay to the spherical ground state and unhindered decay to a surprisingly low-lying deformed excited state at 286 keV in the daughter nucleus {sup ...

Mean-square charge radii and magnetic moments have been measured for the neutron deficient lead isotopes, 182�190Pb. The measurement was performed at the ISOLDE online mass separator, using the in-source resonance ionization spectroscopy technique. The wavelength of the first excitation step for the resonance ionization laser ion source (RILIS) was scanned over the resonance(s) whilst the ?- and ...

Mean-square charge radii and magnetic moments have been measured for the neutron deficient lead isotopes, 182 190Pb. The measurement was performed at the ISOLDE online mass separator, using the in-source resonance ionization spectroscopy technique. The wavelength of the first excitation step for the resonance ionization laser ion source (RILIS) was scanned over the resonance(s) whilst the ?- and ...

The 115, 117, 119, 121In nuclei have been produced as fission fragments in three reactions induced by heavy ions: 12C + 238U at 90MeV bombarding energy, 18O + 208Pb reaction at 85MeV, and 31P + 176Yb at 152MeV. Their level schemes have been built from gamma-rays detected using the EUROBALL III and IV arrays. High-spin states of 117, 119, 121In nuclei have been identified for the first time. ...

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The properties of high spin states in (Z = 53) ^{113}I, ^ {117}I, ^{121} I and ^{125,127}I nuclei have been investigated using the techniques of gamma-spectroscopy. A surprisingly broad diversity of nuclear structure effects has been observed across the 60 < N < 74 isotopic chain. The experimental results have been interpreted within the framework of several nuclear models. In ^{113}I, five ...

Atomic spectroscopy measurements were carried out using the COMPLIS setup installed at the ISOLDE-BOOSTER facility. Hyperfine structure (HFS) spectra and isotope shift (IS) values were obtained for the neutron-deficient 178-185Pt and for 184Aug,m, providing deformation parameters ? , magnetic moments ? and spectroscopic quadrupole moments (for I ? 1) Qs . In Pt isotopes, a deformation drop for ...

AUTOBATCH was developed to provide a usable source of short-lived neutron-rich nuclides through chemical preparation of the sample from fission products for detailed gamma-ray spectroscopy, which would complement the output of on-line isotope separators. With AUTOBATCH the gamma rays following the ..beta../sup -/ decay of /sup 83/As were studied to determine the ground state spin and parity of ...

AUTOBATCH was developed to provide a usable source of shortlived neutron-rich nuclides through chemical preparation of the sample from fission products for detailed gamma-ray spectroscopy, which would complement the output of on-line isotope separators. With AUTOBATCH the gamma rays following the ..beta..-decay of /sub 33//sup 83/As/sub 5//sup 0/ were studied to determine: (1) the ground state ...

The work described in this thesis deals with two of the many applications of the Fragment Mass Analyzer, a recoil mass spectrometer installed at the ATLAS facility at Argonne National Laboratory. The rapid-proton capture (rp-) process has been recognized as a key contributor to the nucleosynthesis of heavy elements in massive stars. Understanding the production rate of each element is a chain of ...

Intruder state excitation energies in odd-mass nuclei just outside a closed proton shell plotted versus neutron number generally exhibit parabola-shaped curves with minima near neutron mid-shells. The Bi isotopes, however, do not seem to follow this trend. Recent experiments performed at Argonne National Laboratory have identified the previously unobserved {sup 187}Bi ground ...