Photoactivation experiment onAu197and its implications for the dipole strength in heavy nuclei

Abstract

The 197 Au(γ, n) reaction is used as an activation standard for photodisintegration studies on astrophysically relevant nuclei. At the bremsstrahlung facility of the superconducting electron accelerator ELBE (Electron Linear accelerator of high Brilliance and low Emittance) of Forschungszentrum Dresden-Rossendorf, photoactivation measurements on 197 Au have been performed with bremsstrahlung endpoint energies from 8.0 to 15.5 MeV. The measured activation yield is compared with previous experiments as well as with calculations using Hauser-Feshbach statistical models. It is shown that the experimental data are best described by a two-Lorentzian parametrization with taking the axial deformation of 197 Au into account. The experimental 197 Au(γ, n) reaction yield measured at ELBE via the photoactivation method is found to be consistent with previous experimental data using photon scattering or neutron detection methods.

Activation Experiments forp-Process Nucleosynthesis

“…Measurements were performed with continuousenergy bremsstrahlung photons [25,26,27,28,29] and quasi-monoenergetic photons from Laser Compton Backscattering (LCB) [30,31,32] (see [33] as review). In near future, also tagged photons will be available with high energy resolution in the astrophysically relevant energy range at the low-energy photon tagger NEPTUN at the S-DALINAC, Darmstadt [34,35].…”

Splitting of the Pygmy Dipole Resonance

“…Using tagged photons at the NEPTUN facility [32,33] will allow to close the gap between the IVGDR and the low-energy strength. At this new experimental site, photon-induced experiments can be studied independently of limitations due to the particle thresholds, which will also play an important role in extending systematics on photon-induced reactions for nuclear astrophysics [34, 35,36,37]. On exotic nuclei, further systematics will be collected in order to confirm the dependence of the PDR on the neutron excess and also to connect to the experiments on the stable isotopes.…”

Photoneutron Cross Sections for Au Revisited: Measurements with Laser Compton Scattering γ-Rays and Data Reduction by a Least-Squares Method

“…14) in the energy range of 8.23-12.17 MeV. A comparison with the photoactivation data of Nair et al 13) is not feasible because the data is available only in the form of activation yield. The cross section by Varlamov et al 30) is also shown in Fig.…”

“…Recently, photoactivation measurements for Au have been extended from the threshold to the peak energy region of GDR. 13) Photoneutron cross sections for Au were previously measured as reference data for determining 152 Sm(,n) cross sections with LCS -rays at the National Institute of Advanced Industrial Science and Technology (AIST). 14) However, a data reduction by the photon difference method has ended up with large uncertainties.…”