First application of the Oslo method in inverse kinematics

International audienceThe $\gamma$-ray strength function ($\gamma$SF) and nuclear level density (NLD) have been extracted for the first time from inverse kinematic reactions with the Oslo method. This novel technique allows measurements of these properties across a wide range of previously inaccessible nuclei. Proton–$\gamma$ coincidence events from the $\mathrm {d}(^{86}\mathrm {Kr}, \mathrm {p}\gamma )^{87}\mathrm {Kr}$ reaction were measured at iThemba LABS and the $\gamma$SF and NLD in $^{87}\mathrm {Kr}$ was obtained. The low-energy region of the $\gamma$SF is compared to shell-model calculations, which suggest this region to be dominated by M1 strength. The $\gamma$SF and NLD are used as input parameters to Hauser–Feshbach calculations to constrain $(\mathrm {n},\gamma )$ cross sections of nuclei using the TALYS reaction code. These results are compared to $^{86}\mathrm {Kr}(n,\gamma )$ data from direct measurements

Nuclear level densities and γ\gamma-ray strength functions of 87Kr^{87}\mathrm{Kr} -- First application of the Oslo Method in inverse kinematics

The $\gamma$-ray strength function ($\gamma$SF) and nuclear level density (NLD) have been extracted for the first time from inverse kinematic reactions with the Oslo Method. This novel technique allows measurements of these properties across a wide range of previously inaccessible nuclei. Proton-$\gamma$ coincidence events from the $\mathrm{d}(^{86}\mathrm{Kr}, \mathrm{p}\gamma)^{87}\mathrm{Kr}$ reaction were measured at iThemba LABS and the $\gamma$SF and NLD in $^{87}\mathrm{Kr}$ obtained. The low-energy region of the $\gamma$SF is compared to Shell Model calculations which suggest this region to be dominated by M1 strength. The $\gamma$SF and NLD are used as input parameters to Hauser-Feshbach calculations to constrain $(\mathrm{n},\gamma)$ cross sections of nuclei using the TALYS reaction code. These results are compared to $^{86}\mathrm{Kr}(n,\gamma)$ data from direct measurements

Gamma-ray emission in proton-induced nuclear reactions on natC and Mylar targets over the incident energy range of Ep = 30-200 MeV. Astrophysical implications

We have measured the gamma-ray line production cross sections in proton-induced nuclear reactions on various target nuclei abundant in astrophysical sites over the incident energy range of Ep = 30 - 200 MeV. We carried out experimental campaigns in joint collaboration at the K = 200 cyclotron of iThemba LABS using a high-energy resolution, high-efficiency detection array composed of 8 Compton-suppressed clover detectors comprising 32 HP-Ge crystals for recording the gamma-ray spectra. In the current paper, we focus on de-excitation lines produced in proton irradiations of natC and Mylar targets. In particular, on the prominent 4.439 and 6.129 MeV lines of $^{12}$C and $^{16}$O which are among the strongest lines emitted in solar flares and in interactions of low-energy cosmic rays with the gas and dust of the inner galaxy. We report new gamma-ray production experimental cross section data for ten nuclear lines that we compare to previous low-energy data sets from the literature, to the predictions of the TALYS code of modern nuclear reactions and to a semi-empirical compilation. In first approach, performing calculations with default input parameters of TALYS we observed substantial deviations between the predicted cross sections and experimental data. Then, using modified optical model potential and nuclear level deformation parameters as input data we generated theoretical excitation functions for the above two main lines fully consistent with experimental data. In contrast, the experimental data sets for the other eight analyzed lines from the two proton-irradiated targets exhibit significant deviations with the predicted cross section values. We also report line-shape experimental data for the line complex observed at $E_g$ = 4.44 MeV in irradiations of the two targets. Finally, we emphasize the astrophysical implications of our results

New γ-ray production cross sections for the 4.439 and 6.129 MeV lines of 12^{12}C and 16^{16}O. Astrophysical implications

International audienceGamma-ray line production cross sections from nuclear reactions induced by 30 - 200 MeV protons on $^{nat}$C and Mylar targets have been measured at the SSC facility of iThemba LABS. Results for the 4.439 and 6.129 MeV prominent lines of $^{12}$C and $^{16}$O of astrophysical concern are reported and discussed

Shape analysis of the 4.44 MeV γ-ray line complex produced in inelastic proton scattering off 12^{12}C over the indent energy range of Ep_{p} = 30−200 MeV

International audienceWe report γ-ray spectra for the line observed at E$_{γ}$ = 4.44 MeV in our previous experiments at iThemba LABS’ SSC facility using 30 - 200 MeV proton beams to irradiate a $^{nat}$C target. It is actually a complex composed of several lines of interest broadened by Doppler effect. In addition to the dominant 4.439 MeV line of $^{12}$C, two other lines at E$_{γ}$ = 4.319 and 4.445 MeV assigned to $^{11}$C and $^{11}$B, respectively, are significant components of this complex. The analysis of its line shapes based on nuclear reaction models is the main topic of this contribution