Dipole strength inSe80forsprocess and nuclear transmutation ofSe79

Abstract

The dipole strength distribution of 80 Se was studied in a photon-scattering experiment by using bremsstrahlung produced with an electron beam of energy 11.5 MeV at the linear accelerator ELBE. We identified 180 γ transitions up to an energy of 9.6 MeV, and analyzed the strength in the quasicontinuum of the spectrum. Simulations of statistical γ -ray cascades were performed to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. The photoabsorption cross section below the neutron-separation energy derived in this way was combined with the photoabsorption cross section obtained from an earlier (γ,n) experiment and used as an input for the calculation of 79 Se(n,γ ) reaction rates on the basis of the statistical reaction model.

Photoexcitation of $^{76}$Ge

“…The atomic background amounts in average to only a few percent of the intensity in the spectrum, but coincides with that above the neutron threshold, which proves the right magnitude. This behavior is similar to that found in previous studies [32,[44][45][46][47][48][49][50] and shows that the experimental spectrum contains a considerable amount of nuclear strength in a quasicontinuum. This is formed by a large number of unresolved transitions with small intensities that are the result of the increasing nuclear level density at high energy in combination with the finite detector resolution.…”

Electric and magnetic dipole strength in Fe54

“…4. As found in previous studies [5,6,12,27,[39][40][41][42] the continuum in the spectrum of γ rays scattered from 54 Fe is considerably higher than the background due to atomic scattering. This continuum is formed by a large number of unresolved transitions with small intensities that are a consequence of the increasing nuclear level density at high excitation energies in connection with the finite detector resolution.…”

Dipole strength distribution in Pb206 for the evaluation of the neutron capture cross section of Pb205

“…Here, I γ (E γ , θ) and I γ (E B γ , θ) denote efficiency-corrected intensities of a ground-state transition at E γ and of a ground state transition in 11 and W (E B γ , θ) represent the angular correlations of these transitions. The quantities Φ(E x ) and Φ γ (E B…”

“…However, no experimental data of capture cross sections at the fast-neutron energy region is available. To evaluate the neutron capture cross sections of 205 Pb, nuclear photon scattering or nuclear resonance fluorescence (NRF) data combined with the photo-neutron (γ, n) data can be used [9][10][11].…”