"Soft dipole modes - Overview and recent results*"
Sunniva Siem, University of Oslo
(id #208)
Seminar: NoPoster: No
Invited talk: Yes
Soft dipole modes – Overview and resent results*
Sunniva Siem1, Alexander Bürger1, Andreas Görgen1,2, Magne Guttormsen1,
Ann-Cecilie Larsen1, Hilde Therese Nyhus1, John Rekstad1, Therese Renstrøm1, Andreas Schiller3, Naeem U.H.Syed1, Heidi Toft1, Gry M. Tveten1 and Alexander Voinov3
1Dept. of Physics, University of Oslo, P.O.Box 1048 Blindern, 0316 Oslo, Norway,
2CEA Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France
3Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
The gamma-strength functions is a fundamental property of the atomic nucleus and an
important input parameter in reaction cross-section calculations, used in reactor physics
and astrophysics models of formation of heavy elements in explosive stellar environments.
The Giant Electric Dipole Resonance (GEDR) dominates the gamma-strength function and is found in all nuclei across the nuclear chart. The focus of this talk however is the smaller resonances, also called soft dipole modes, found on the low energy tail of the GEDR. One of these is the scissors mode observed (at around 3 MeV) in deformed nuclei and has been studied by several groups using complementary experimental techniques. Another soft dipole mode observed at around 7-9 MeV might be due to neutron skin oscillations. In experiment done in Oslo an unexpected enhancement of the gamma-strength function at low gamma energy has been observed in several nuclei. The origin of this enhancement is presently not understood and remains a challenge to explain theoretically.
This talk will give an overview of the different soft dipole modes, including the different experimental techniques used to study the gamma strength function. Resent results will be presented and the possible impact of soft dipole modes and the low energy enhancement on astrophysical reaction rates and the calculated abundances of elements in our solar system, will be discussed.
*This work was supported by the Norwegian Research Council.
Sunniva Siem1, Alexander Bürger1, Andreas Görgen1,2, Magne Guttormsen1,
Ann-Cecilie Larsen1, Hilde Therese Nyhus1, John Rekstad1, Therese Renstrøm1, Andreas Schiller3, Naeem U.H.Syed1, Heidi Toft1, Gry M. Tveten1 and Alexander Voinov3
1Dept. of Physics, University of Oslo, P.O.Box 1048 Blindern, 0316 Oslo, Norway,
2CEA Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France
3Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA
The gamma-strength functions is a fundamental property of the atomic nucleus and an
important input parameter in reaction cross-section calculations, used in reactor physics
and astrophysics models of formation of heavy elements in explosive stellar environments.
The Giant Electric Dipole Resonance (GEDR) dominates the gamma-strength function and is found in all nuclei across the nuclear chart. The focus of this talk however is the smaller resonances, also called soft dipole modes, found on the low energy tail of the GEDR. One of these is the scissors mode observed (at around 3 MeV) in deformed nuclei and has been studied by several groups using complementary experimental techniques. Another soft dipole mode observed at around 7-9 MeV might be due to neutron skin oscillations. In experiment done in Oslo an unexpected enhancement of the gamma-strength function at low gamma energy has been observed in several nuclei. The origin of this enhancement is presently not understood and remains a challenge to explain theoretically.
This talk will give an overview of the different soft dipole modes, including the different experimental techniques used to study the gamma strength function. Resent results will be presented and the possible impact of soft dipole modes and the low energy enhancement on astrophysical reaction rates and the calculated abundances of elements in our solar system, will be discussed.
*This work was supported by the Norwegian Research Council.
