Total and partial cross sections of the ${}^{112}$Sn($\alpha ,\gamma$)${}^{116}$Te reaction measured via in-beam $\gamma$-ray spectroscopy

Abstract

An extended database of experimental data is needed to address uncertainties of the nuclear-physics input parameters for Hauser-Feshbach calculations. Especially $\alpha$+nucleus optical model potentials at low energies are not well known. The in-beam technique with an array of high-purity germanium (HPGe) detectors was successfully applied to the measurement of absolute cross sections of an ($\alpha$,$\gamma$) reaction on a heavy nucleus at sub-Coulomb energies. The total and partial cross-section values were measured by means of in-beam $\gamma$-ray spectroscopy. Total and partial cross sections were measured at four different $\alpha$-particle energies from $E_{\alpha }=10.5$ MeV to $E_{\alpha }=12$ MeV. The measured total cross-section values are in excellent agreement with previous results obtained with the activation technique, which proves the validity of the applied method. The experimental data was compared to Hauser-Feshbach calculations using the nuclear reaction code TALYS. A modified version of the semi-microscopic $\alpha$+nucleus optical model potential OMP 3, as well as modified proton and $\gamma$ widths, are needed in order to obtain a good agreement between experimental data and theory. It is found, that a model using a local modification of the nuclear-physics input parameters simultaneously reproduces total cross sections of the ${}^{112}$Sn($\alpha$,$\gamma$) and ${}^{112}$Sn($\alpha$,p) reactions. The measurement of partial cross sections turns out to be very important in this case in order to apply the correct $\gamma$-ray strength function in the Hauser-Feshbach calculations. The model also reproduces cross-section values of $\alpha$-induced reactions on ${}^{106}$Cd, as well as of ($\alpha$,n) reactions on ${}^{115,116}$Sn, hinting at a more global character of the obtained nuclear-physics input.

8 pages, 9 figures

References in corpus (11)

• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• Alpha-induced cross sections of 106Cd for the astrophysical p-process
• Cross section measurements of $\alpha$-induced reactions on ${}^{92,94}$Mo and ${}^{112}$Sn for $p$-process studies
• 70Ge(p,gamma)71As and 76Ge(p,n)76As cross sections for the astrophysical p process: sensitivity of the optical proton potential at low energies
• The gamma-ray spectrometer HORUS and its applications for nuclear astrophysics
• Alpha induced reaction cross section measurements on 162Er for the astrophysical gamma process
• Investigation of the reaction 74Ge(p,gamma)75As using the in-beam method to improve reaction network predictions for p nuclei
• Cross sections for proton-induced reactions on Pd isotopes at energies relevant for the gamma process
• Experimental cross sections of 165Ho(α,n)168Tm and 166Er(α,n)169Yb for optical potential studies relevant for the astrophysical γ-process
• Cross-section measurement of the ${}^{130}$Ba(p,$\gamma$)${}^{131}$La reaction for $\gamma$-process nucleosynthesis
• Measurement of the ${}^{58}$Ni($\alpha$,$\gamma$)${}^{62}$Zn reaction and its astrophysical impact

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