Measurements consisting of γ-ray excitation functions and angular distributions have been performed using the (n, n ′ γ) reaction on 62 Ni. The excitation function data allowed us to check the consistency of the placement of transitions in the level scheme. From γ-ray angular distributions, the lifetimes of levels up to ∼ 3.8 MeV in excitation energy have been extracted with the Doppler-shift attenuation method. The experimentally deduced values of reduced transition probabilities have been compared with the predictions of the quadrupole vibrator model and with large-scale shell model calculations in the f p shell configuration space. Two-phonon states have been found to exist with some notable deviation from the predictions of the quadrupole vibrator model, but no evidence for the existence of three-phonon states could be established. Z = 28 proton core excitations play a major role in understanding the observed structure.

Background: Astrophysical models studying the origin of the neutron-deficient p nuclides require the knowledge of proton capture cross sections at low energy. The production site of the p 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 74 Ge(p,γ) 75 As at low proton energies, inside the astrophysically relevant energy region, is important in several respects. The reaction is directly important as it is a bottleneck in the reaction flow which produces the lightest p nucleus 74 Se. It is also an important addition to the data set required to test reaction-rate predictions and to allow an improvement in the global p+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 γ-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 twelve 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 in 75 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 74 Ge, 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 74 As(n,γ) 75 As rate. Conclusions:Between data and statistical model prediction a factor of about two was found. Nevertheless, the improved astrophysical reaction rate of 74 Ge(p,γ) (and its reverse reaction) is only 28% larger than the previous standard rate. The prediction of the 74 As(n,γ) 75 As 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.

Inelastic neutron scattering was used to study the low-lying nuclear structure of 132 Xe. A comprehensive level scheme is presented, as well as new level lifetimes, multipole mixing ratios, branching ratios, and transition probabilities. Comparisons of these data as well as previously measured E2 strengths and g factors are made with new shell-model calculations for 132,134,136 Xe to explore the emergence of collectivity in the Xe isotopes with N < 82 near the closed shell. *

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