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Lifetimes of yrast and nonyrast states of 102Pd populated via the 92Zr( 13C, 3n) reaction are measured by means of the recoil distance Doppler-shift technique with a Cologne plunger coupled to a GASP spectrometer. The event-by-event data accumulated at 24 plunger distances in the range of 0.1 μm to 9 mm are analyzed using the differential decay curve method. The resulting B(E2) values of the γ transitions depopulating yrast-band members up to the I π = 8+ state are found to deviate significantly from the corresponding predictions of the E(5) critical-point symmetry. [ABSTRACT FROM AUTHOR]

Background: Astrophysical models studying the origin of the neutron-deficient ρ nuclides require knowledge of proton capture cross sections at low energy. The production site of the ρ nuclei is still under discussion but a firm basis of nuclear reaction rates is required to address the astrophysical uncertainties. Data at astrophysically relevant interaction energies are scarce. Problems with the prediction of charged particle capture cross sections at low energy were found in the comparisons between previous data and calculations in the Hauser-Feshbach statistical model of compound reactions. Purpose: A measurement of 74Ge(p, y)75As at low proton energies, inside the astrophysically relevant energy region, is important in several respects. The reaction is directly important because it is a bottleneck in the reaction flow which produces the lightest ρ nucleus 74Se. It is also an important addition to the data set required to test reaction-rate predictions and to allow an improvement in the global ρ + nucleus optical potential required in such calculations. Method: An in-beam experiment was performed, making it possible to measure in the range 2.1 ≤ Ep ≤3.7 MeV, which is for the most part inside the astrophysically relevant energy window. Angular distributions of the )/-ray transitions were measured with high-purity germanium detectors at eight angles relative to the beam axis. In addition to the total cross sections, partial cross sections for the direct population of 12 levels were determined. Results: The resulting cross sections were compared to Hauser-Feshbach calculations using the code SMARAGD. Only a constant renormalization factor of the calculated proton widths allowed a good reproduction of both total and partial cross sections. The accuracy of the calculation made it possible to check the spin assignment of some states in75 As. In the case of the 1075-keV state, a double state with spins and parities of 3/2- and 5/2- is needed to explain the experimental partial cross sections. A change in parity from 5/2+ to 5/2- is required for the state at 401 keV. Furthermore, in the case of 74Ge, studying the combination of total and partial cross sections made it possible to test the γ width, which is essential in the calculation of the astrophysical 74As(n,?)75As rate. Conclusions: Between data and statistical model prediction a factor of about two was found. Nevertheless, the improved astrophysical reaction rate of 74Ge(/?, γ) (and its reverse reaction) is only 28% larger than the previous standard rate. The prediction of the 74As(n,y)75As rate (and its reverse) was confirmed, the newly calculated rate differs only by a few percent from the previous prediction. The in-beam method with high-efficiency detectors proved to be a powerful tool for studies in nuclear astrophysics and nuclear structure. [ABSTRACT FROM AUTHOR]