Splitting of the Pygmy Dipole Resonance

Journal Article · Fri Oct 28 00:00:00 EDT 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3628389· OSTI ID:21612061

Endres, J; Zilges, A ^[1]; Butler, P; Herzberg, R -D; Scheck, M ^[2]; Harakeh, M N ^[3]; Harissopulos, S; Lagoyannis, A ^[4]; Kruecken, R; Ring, P ^[5]; Litvinova, E ^[3]; Pietralla, N; Ponomarev, V Yu; Sonnabend, K ^[6]; Popescu, L ^[7]; Savran, D ^[8]; Stoica, V I ^[9]; Woertche, H J ^[9]

---

1. Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany)
2. Oliver Lodge Laboratory, University of Liverpool, L69 7ZE (United Kingdom)
3. GSI Helmholtzzentrum fuer Schwerionenforschung, D-64291 Darmstadt (Germany)
4. Institute of Nuclear Physics, N.C.S.R. Demokritos Athens, GR-15310 Athens (Greece)
5. Physik Department, TU Muenchen, D-85748 Garching (Germany)
6. Institut fuer Kernphysik, TU Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt (Germany)
7. Belgian Nuclear Research Centre SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)
8. ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, D-64291 Darmstadt (Germany)
9. Kernfysisch Versneller Instituut, University of Groningen, 9747 AA Groningen (Netherlands)

In recent years investigations have been made to study the electric Pygmy Dipole Resonance (PDR) systematically, mainly in semi-magic nuclei. For this purpose the well understood high resolution ({gamma},{gamma}') photon scattering method is used. In complementary ({alpha},{alpha}'{gamma}) coincidence experiments at E{sub {alpha}} = 136 MeV a similar {gamma}-energy resolution and a high selectivity to E1 transitions can be obtained at the Big-Bite Spectrometer (BBS) at KVI, Groningen. In comparison to the ({gamma},{gamma}') method a structural splitting of the PDR is observed in the N = 82 nuclei {sup 138}Ba and {sup 140}Ce and in the Z = 50 nucleus {sup 124}Sn. The low energy part is excited in ({gamma},{gamma}') as well as in ({alpha},{alpha}'{gamma}) while the high energy part is observed in ({gamma},{gamma}') only. The experimental results together with theoretical QPM and RQTBA calculations on {sup 124}Sn which are able to reproduce the splitting of the PDR qualitatively are presented. The low-lying group of J{sup {pi}} = 1{sup -} states seem to represent the more isoscalar neutron-skin oscillation of the PDR while the energetically higher-lying states seemingly belong to the transitional region between the PDR and the isovector Giant Dipole Resonance (IVGDR).

• OSTI ID: 21612061
• Journal Information: AIP Conference Proceedings, Vol. 1377, Issue 1; Conference: FINUSTAR 3 Conference on frontiers in nuclear structure, astrophysics, and reactions, Rhodes (Greece), 23-27 Aug 2010; Other Information: DOI: 10.1063/1.3628389; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARIUM 138
CERIUM 140
COMPARATIVE EVALUATIONS
DIPOLES
E1-TRANSITIONS
ELECTROMAGNETIC FIELDS
ENERGY RESOLUTION
FINE STRUCTURE
MAGIC NUCLEI
MEV RANGE
NEUTRONS
NUCLEAR STRUCTURE
PHOTONS
QUASI PARTICLES
RESONANCE
SCATTERING
TIN 124
ALKALINE EARTH ISOTOPES
BARIUM ISOTOPES
BARYONS
BOSONS
CERIUM ISOTOPES
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EVALUATION
EVEN-EVEN NUCLEI
FERMIONS
HADRONS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MASSLESS PARTICLES
MULTIPOLE TRANSITIONS
MULTIPOLES
NANOSECONDS LIVING RADIOISOTOPES
NUCLEI
NUCLEONS
RADIOISOTOPES
RARE EARTH NUCLEI
RESOLUTION
STABLE ISOTOPES
TIN ISOTOPES