The collective bands of 75Kr were extended up to spin 45/2 using the compound reactions 5°Cr(28Si,2pn), 54Fe(24Mg,2pn) and 58Ni(2°Ne,2pn)YSKr. Lifetimes were measured by RDDS with nine OSIRIS detectors in coincidence. Mixing ratios were determined by measurements of internal conversion coefficients, angular distribution and correlations. Deviations between different measurements are explained by the short lifetimes leading to angle dependent intensity losses due to Doppler shift. Spins and parities were assigned from angular distributions, excitation functions and DCO ratios measured with the OSIRIS_12 spectrometer. The band head spin of the negative parity yrast band was established as 3/2 via DCO ratios and internal conversion coefficients. Further bands at low excitation energy were found. In accordance to Woods-Saxon cranking model calculations, these weaker populated sidebands are interpreted to be built on oblate deformed intrinsic states (/32 ~ -0.2), while the strongly populated bands are built on prolate deformed states (~2 ~ +0.4). The interpretation of the lqp g9/2 yrare band, to be generated from oblate deformation, is further supported by A1 = 0 transitions into the yrast band and a similar oblate deformed g9/z structure in the isotone 73Se. The experimental level energies, branching ratios, transition probabilities and mixing ratios are compared to rotor model calculations. The deviations between experiment and rotor model calculations are interpreted to be based on mixing between prolate and oblate states.

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Doppler shift attenuation lifetime measurements have been carried out for the 3qp and isomeric rotational bands in S3y using the reaction ~SNi(2Ssi,3p). While the transitional quadrupole moments in the 3qp bands are slightly lower than in the lqp bands, we found evidence for a strong reduction in IQt[ for the isomeric band. PACS :21.60.Ev; 27.50.+e Recent work [1][2][3][4] on the S3y isotope has revealed interesting insights concerning interplay between collective and single particle behavior in the mass 80 region. In the first in-beam study [1] of s3y, several rotational sequences were found. The positive-parity yrast band exhibited a bandcrossing interpreted [4] as being due to g9/2 neutron alignment. The negative parity favored signature sequence forked into two separate bands. The bandcrossing in the yrast band was interpreted as a proton alignment. The second branch of this forking had a rotational structure feeding into the 62 ps lived 17/2~-state. We shall refer to this band as an isomeric band. Between the isomeric band and the yrast negative parity band were seen no cross transitions, in spite of the near degeneracy in energies. G-factor measurements [3] suggested that a complex n-p rotation-aligned configuration was the underlying structure. Lifetime measurements of S3y indicated decreasing [Qt] for the 3qp structure and rather large deformations for the lower spin states in the yrast negative-parity band. But in the isomeric band, except for the 17/2-and 19/2-states, no lifetimes are available.The lifetime measurements have been extended using the Doppler-shift attenuation method. The reaction used was 5SNi(2ssi,3p)SaY at 95. MeV using the Cologne tandem accelerator. The target was an 99.8 % enriched 0.38mg/cm 2 thick 5SNi foil. Six Comptou-supressed detectors were placed in a ring positioned at 900 and one at 0 ~ relative to the beam axis. Doppler shifted lineshapes were obtained, by observing lines in the 0 ~ detector in coincidence with those at 900 .Transitions investigated are shown in the partial level scheme of S3y in Fig. 1. Lineshapes were analyzed with the code GNOMON [2-5]. Side-feeding was treated as in [2,6]. All lifetimes, together with inferred electromagnetic properties are given in Table 1. Because of the doublet structure of many 7-ray lines, some relevant details of the DSA analysis are presented. The effective lifetimes of the (41/2 + ) and (37/2 + ) states were nearly the same (,--0.24 ps) and so an upper limit of 0.10 ps is assigned to the (37/2 +) level. The sidefeeding has the same upper limit. Both cascade-and side-feeding were taken into account in the analysis of the 1340 keV transition. The side-feeding was varied from 0.01 to 0.50 ps; minimum X ~ were found for v,] --0.08,0.31 ps. Since the side-feeding time for the (37/2 + ) level clearly had an upper limit of 0.10 ps, the second minimum (0.31 ps) was excluded since an increase of 0.20 ps in the side-feeding time would be unreasonable [6]. This choice is also consistent with the previous [2] suggestion as to the...

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