E1 and M1 strength functions at low energy

Conference Paper

We report photon-scattering experiments using bremsstrahlung at the γELBE facility of Helmholtz-Zentrum Dresden-Rossendorf and using quasi-monoenergetic, polarized γ beams at the HIγS facility of the Triangle Universities Nuclear Laboratory in Durham. To deduce the photoabsorption cross sections at high excitation energy and high level density, unresolved strength in the quasicontinuum of nuclear states has been taken into account. In the analysis of the spectra measured by using bremsstrahlung at γELBE, we perform simulations of statistical γ-ray cascades using the code γDEX to estimate intensities of inelastic transitions to low-lying excited states. Simulated average branching ratios are compared with model-independent branching ratios obtained from spectra measured by using monoenergetic γ beams at HIγS. E1 strength in the energy region of the pygmy dipole resonance is discussed in nuclei around mass 90 and in xenon isotopes. M1 strength in the region of the spin-flip resonance is also considered for xenon isotopes. The dipole strength function of 74Ge deduced from γELBE experiments is compared with the one obtained from experiments at the Oslo Cyclotron Laboratory. The low-energy upbend seen in the Oslo data is interpreted as M1 strength on the basis of shell-model calculations.

Full Text

Duke Authors

Cited Authors

  • Schwengner, R; Massarczyk, R; Bemmerer, D; Beyer, R; Junghans, AR; Kögler, T; Rusev, G; Tonchev, AP; Tornow, W; Wagner, A

Published Date

  • September 13, 2017

Published In

Volume / Issue

  • 146 /

Electronic International Standard Serial Number (EISSN)

  • 2100-014X

International Standard Serial Number (ISSN)

  • 2101-6275

International Standard Book Number 13 (ISBN-13)

  • 9782759890200

Digital Object Identifier (DOI)

  • 10.1051/epjconf/201714605001

Citation Source

  • Scopus