J. Enders

Experimental simulation of a stellar photon bath by bremsstrahlung: the astrophysical gamma-process

The nucleosynthesis of heavy proton-rich nuclei in a stellar photon bath at temperatures of the astrophysical

Measurement of the (y,n) reaction rates of the nuclides 190Pt, 192Pt, and 198Pt in the astrophysical y process

\gamma

Fine structure of the E1 response in 140Ce below the particle threshold

-process was investigated where the photon bath was simulated by the superposition of bremsstrahlung spectra with different endpoint energies. The method was applied to derive (

Level spacing distribution of scissors mode states in heavy deformed nuclei

\gamma

Two-phonon J = 1 states in even-mass Te isotopes with A = 122–130☆

,n) cross sections and reaction rates for several platinum isotopes.The nucleosynthesis of heavy proton-rich nuclei in a stellar photon bath at temperatures of the astrophysical gamma-process was investigated where the photon bath was simulated by the superposition of bremsstrahlung spectra with different endpoint energies. The method was applied to derive (gamma,n) cross sections and reaction rates for several platinum isotopes

Fragmentation and systematics of the pygmy dipole resonance in the stable N=82 isotones

The nucleosynthesis of heavy neutron-deficient nuclei in a stellar photon bath at the temperatures relevant for the astrophysical gamma process was investigated. In order to derive (gamma,n) cross sections and reaction rates, the stellar photon bath was simulated by the superposition of several bremsstrahlung spectra with different endpoint energies. As a first test for this method, the (gamma,n) reaction rates of the platinum isotopes 190Pt, 192Pt, and 198Pt were derived. The results are compared to other experimental data and theoretical calculations.

Change of the dipole strength distributions between the neighbouring γ-soft nuclei 194Pt and 196Pt☆

Abstract The E1 response of the semi-magic nucleus 140Ce below the particle threshold was measured in a (γ,γ′) experiment utilizing the new Euroball Cluster detector at the S-DALINAC. While the energy averaged data are in good agreement with tagged photon results, here they are resolved for the first time into 54 individual transitions. A quasiparticle-phonon model calculation including up to three-phonon configurations compares well to the extracted strength distribution. The interference between one- and two-phonon contributions is essential for a quantitative reproduction.

Complete scissors mode strength in heavy deformed odd-mass nuclei: a case study of 165Ho and 169Tm

We analyse the level spacing distributions of scissors mode states in heavy deformed nuclei. To this end, we use an ensemble of photon scattering data of 13 nuclei. The results are consistent with a Poissonian behaviour which indicates that the correlations between the states are weak only. The significance of this finding is critically investigated. With numerical simulations we study the possible influence of detection thresholds in the photon scattering experiments. A similar analysis of other dipole modes suggests that the collective nature shown for the scissors mode may be a general phenomenon of low-lying states in deformed nuclei. q 2000 Elsevier Science B.V. All rights reserved.

Photon scattering off 52Cr: two-phonon E1 strength at the N = 28 shell closure?

Abstract Excited states of the nuclei 122,126,130 Te were populated via the (γ, γ′) reaction at endpoint energies of the bremsstrahlung between 4.5 and 5.5 MeV. Gamma rays were detected with a EUROBALL CLUSTER detector and a single HPGe detector. In all investigated nuclei two or three prominent dipole transitions were identified at E γ ≈ 3 MeV. The corresponding low-lying J = 1 states are interpreted as two-phonon excitations. Quasiparticle-phonon-model calculations predict at about 3 MeV one 1 − state arising from the coupling of the first quadrupole and the first octupole phonon, and one 1 + state arising from the coupling of the first and the second quadrupole phonon, where the latter has isovector character. Such an excitation mode can be considered as an analogue of the scissors mode in vibrational nuclei. The calculated transition strengths are compatible with experimental ones within a factor of about 1.5.

Single proton knock-out reactions fromF24,25,26

The low-lying electric dipole (