Journalartikel
Autorenliste: FRIEDRICHS, H; LINDENSTRUTH, S; SCHLITT, B; WESSELBORG, C; BAUSKE, I; HEIL, RD; KNEISSL, U; MARGRAF, J; PITZ, HH; HAGER, D; MULLER, G; SCHUMACHER, M; VONBRENTANO, P; HERZBERG, RD; ZILGES, A
Jahr der Veröffentlichung: 1993
Seiten: C553-C556
Zeitschrift: Nuclear Physics A: Nuclear and Hadronic Physics
Bandnummer: 553
ISSN: 0375-9474
eISSN: 1873-1554
Verlag: Elsevier
Abstract:
Systematic nuclear resonance fluorescence (NRF) experiments have been performed at the bremsstrahlung facility of the Stuttgart Dynamitron to investigate the distribution of magnetic and electric dipole strengths in deformed nuclei. Precise excitation energies, transition strengths, spins and decay branching ratios were deduced for numerous low lying dipole excitations in deformed rare earth nuclei. Measurements of the linear polarization of resonantly scattered photons using simultaneously two Compton polarimeters enabled model independent parity assignments. For the first time positive parities could be established for groups of states in the neighbouring deformed nuclei 150Nd, Gd-160, Dy-162. Most of these states are concentrated near 3 MeV and should be attributed to orbital M1 excitations (''Scissors Mode''). The deformation dependence of the orbital M1 strength has been studied in the Nd isotopic chain. Completing previous polarization measurements on Nd-142, Nd-150 the transitional nucleus Nd-146 has been investigated. The surprising novel result of the present systematic studies, however, was the first observation of enhanced electric dipole excitations in the same deformed nuclei at excitation energies of 2.414, 2.471, and 2.520 MeV, respectively. The transition energies and the enhanced B(E1)up strengths of 3-5.10(-3) e2fm2 support the interpretation in terms of the predicted new type of collective electric dipole excitations in deformed nuclei due to reflection asymmetric shapes like octupole deformations and/or cluster configurations. Furthermore, all three states systematically exhibit decay branching ratios R(exp) = B(1- --> 2(1)+)/B(1- --> 0(1)+), which hint at K-mixing. First results for the neutron-odd, deformed nucleus Dy-163 are presented.
Zitierstile
Harvard-Zitierstil: FRIEDRICHS, H., LINDENSTRUTH, S., SCHLITT, B., WESSELBORG, C., BAUSKE, I., HEIL, R., et al. (1993) IDENTIFICATION OF STRONG E1-GROUND-STATE AND M1-GROUND-STATE TRANSITIONS IN DEFORMED RARE-EARTH NUCLEI, Nuclear Physics A: Nuclear and Hadronic Physics, 553, pp. C553-C556
APA-Zitierstil: FRIEDRICHS, H., LINDENSTRUTH, S., SCHLITT, B., WESSELBORG, C., BAUSKE, I., HEIL, R., KNEISSL, U., MARGRAF, J., PITZ, H., HAGER, D., MULLER, G., SCHUMACHER, M., VONBRENTANO, P., HERZBERG, R., & ZILGES, A. (1993). IDENTIFICATION OF STRONG E1-GROUND-STATE AND M1-GROUND-STATE TRANSITIONS IN DEFORMED RARE-EARTH NUCLEI. Nuclear Physics A: Nuclear and Hadronic Physics. 553, C553-C556.
Schlagwörter
DIPOLE MODES; PHOTOEXCITATION