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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]

Primary &ggr;-ray spectra for a wide excitation-energy range have been extracted for 44Ti from particle-y coincidence data of the 46Ti(p,t&ggr;)44Ti reaction. These spectra reveal information on the &ggr;-decay pattern of the nucleus and may be used to extract the level density and radiative strength function applying the Oslo method. Models of the level density and radiative strength function are used as input for cross-section calculations of the 40Ca(&agr;,&ggr;)44Ti reaction. Acceptable models should reproduce data on the 40Ca(&agr;,&ggr;)44Ti reaction cross section as well as the measured primary &ggr;-ray spectra. This is only achieved when a coherent normalization of the slope of the level density and radiative strength function is performed. Thus, the overall shape of the experimental primary &ggr;-ray spectra puts a constraint on the input models for the rate calculations. [ABSTRACT FROM AUTHOR]

Abstract: Differential cross-section measurements of the 6Li(d,α0)4He reaction have been performed for deuteron energy between 900 and 2000keV in steps of 25keV. The reaction α particles were detected at four backward angles from 140° to 170° in steps of 10°. A qualitative discussion of the observed variations in the reaction cross sections through the influence of resonances in the d+ 6Li compound system is presented. The results are also compared to existing data, when present, and are validated through benchmarking experiments using high-purity, thick, mirror-polished natural LiF and LiAlO2 targets. [Copyright &y& Elsevier]

Abstract: In the present study the differential cross sections of the 45Sc(p,p)45Sc reaction were measured. Two independent experiments were performed. At first a sandwiched thin ScBr3 target was used for beam energies E LAB =2300–5500keV (in steps of 25 and 50keV) and for detector angles 140°, 160°, and 170°. Secondly a thick Sc2O3 sample was formed and irradiated for E LAB =3100–5500keV with a detector placed at 140°, to validate the results of the first measurement. [Copyright &y& Elsevier]