34 research outputs found
Isospin character of low-lying states in 56Fe.
Low-lying states in {sup 56}Fe, up to an excitation energy of about 4 MeV, have been investigated by means of inelastic proton and deuteron scattering experiments at {ital E}{sub {ital p}}=65 and 400 MeV and at {ital E}{sub {ital d}}=56 MeV, respectively. Measured cross sections and analyzing powers have been compared with coupled-channels calculations using collective form factors; calculations in both the Schr{umlt o}dinger and Dirac formalisms have been carried out for the proton data. For each probe, the matrix elements have been deduced for transitions from the ground state and from the 2{sub 1}{sup +} state to six quadrupole (2{sup +}) states to one octupole (3{sub 1}{sup {minus}}) and two hexadecapole (4{sub 1}{sup +} and 4{sub 2}{sup +}) states. The obtained matrix elements and the previous values from {gamma} decay or electron inelastic scattering have been used to evaluate the isospin character of the transitions. To discuss the quadrupole mixed-symmetry states in {sup 56}Fe, the deduced neutron ({ital M}{sub {ital n}}) and proton ({ital M}{sub {ital p}}) components of the matrix elements, or equivalently the isoscalar ({ital M}{sub {ital s}}) and isovector ({ital M}{sub {ital v}}) parts, have been compared with theoretical calculations based on the neutron-proton interacting bosonmore » model and on the shell model evaluated in a full {ital f}-{ital p} configuration space. {copyright} {ital 1996 The American Physical Society.}« les
Extra γ-ray strength for 116,117Sn arising from pygmy dipole resonance
Photoneutron cross sections were measured for 117Sn and 116Sn near neutron thresholds with quasi-monochromatic laser Compton scattering γ-rays. The measured cross sections for 117Sn and 116Sn are strongly enhanced from the threshold behavior expected for L=1 neutron emissions after E1 photoexcitation. This suggests the presence of extra γ-ray strength in the low-energy tail of the giant dipole resonance. The present cross sections were analyzed together with radiative neutron capture cross sections for 116Sn within the framework of the statistical model calculation. It is shown that the extra γ-ray strength can be interpreted as pygmy E1 resonance which was previously reported in the nuclear resonance fluorescence experiment for 116Sn and 124Sn. © 2010 American Institute of Physics.SCOPUS: cp.pinfo:eu-repo/semantics/publishe
Extra gamma-ray strength for 116,117Sn arising from pygmy dipole resonance
info:eu-repo/semantics/publishe
Partially Ordered Preferences in Decision Trees: Computing Strategies with Imprecision in Probabilities
info:eu-repo/semantics/publishe
γ-ray strength function for Sn116,117 with the pygmy dipole resonance balanced in the photoneutron and neutron capture channels
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Photoneutron cross section measurements on the N=82 nuclei La139 and Pr141: Implications for p-process nucleosynthesis
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Photodisintegration of 181Ta leading to the isomeric state 180Tam
Partial photoneutron cross sections for 181Ta(gamma;n) 180Tam(9-) were measured with laser Compton scattering γ rays. The partial cross section, which reflects selective γ transitions in 180Ta leading to the isomeric state, cast new light into the spin- and parity-dependent nuclear level density of 180Ta. Essentially the same selective γ transition is expected in neutron capture on 179Ta leading to 180Ta m(9-). The weak s-process branching to the only naturally occurring isomer 180Tam is discussed. © Copyright owned by the author(s).SCOPUS: cp.pinfo:eu-repo/semantics/publishe