TY - JOUR

T1 - Microscopic description of the low lying and high lying electric dipole strength in stable Ca isotopes

AU - Tertychny, G.

AU - Tselyaev, V.

AU - Kamerdzhiev, S.

AU - Grümmer, F.

AU - Krewald, S.

AU - Speth, J.

AU - Avdeenkov, A.

AU - Litvinova, E.

N1 - Funding Information: The authors are very thankful to N. Luytorovich for permanent collaboration in the preparation of this Letter and to A. Zilges for the information about the experiments [4] . S. Kamerdzhiev thanks the Institute for Nuclear Theory (Seattle, USA) for partial support during the participation in the Program INT-05-3 which was very useful for this work. J. Speth thanks Stanislaw Drożdż for many discussions and the Foundation for Polish Science for financial support through the Alexander von Humboldt Honorary Research Fellowship . The work was supported in part by the DFG and RFBR grants Nos. GZ:432RUS113/806/0-1 and 05-02-04005 and by the INTAS grant No. 03-54-6545. Copyright: Copyright 2007 Elsevier B.V., All rights reserved.

PY - 2007/4/5

Y1 - 2007/4/5

N2 - The properties of the low lying and high lying electric dipole strength in the stable 40Ca, 44Ca and 48Ca isotopes have been calculated within the Extended Theory of Finite Fermi Systems (ETFFS). This approach is based on the random phase approximation (RPA) and includes the single particle continuum as well as the coupling to low lying collective states which are considered in a consistent microscopic way. For 44Ca we also include pairing correlations. We obtain good agreement with the existing experimental data for the gross properties of the low lying and high lying strength. It is demonstrated that the recently measured A-dependence of the electric dipole strength below 10 MeV is well understood in our model: due to the phonon coupling some of the strength in 48Ca is simply shifted beyond 10 MeV. The predicted fragmentation of the strength can be investigated in (e, e′) and (γ, γ′) experiments. The isovector dipole strength below 10 MeV is small in all Ca isotopes. Surprisingly, the proton and neutron transition densities of these low lying electric dipole states are in phase, which indicate isoscalar structure. We conclude that for the detailed understanding of the structure of excited nuclei e.g. the low lying and high lying electric dipole strength an approach like the present one is absolutely necessary.

AB - The properties of the low lying and high lying electric dipole strength in the stable 40Ca, 44Ca and 48Ca isotopes have been calculated within the Extended Theory of Finite Fermi Systems (ETFFS). This approach is based on the random phase approximation (RPA) and includes the single particle continuum as well as the coupling to low lying collective states which are considered in a consistent microscopic way. For 44Ca we also include pairing correlations. We obtain good agreement with the existing experimental data for the gross properties of the low lying and high lying strength. It is demonstrated that the recently measured A-dependence of the electric dipole strength below 10 MeV is well understood in our model: due to the phonon coupling some of the strength in 48Ca is simply shifted beyond 10 MeV. The predicted fragmentation of the strength can be investigated in (e, e′) and (γ, γ′) experiments. The isovector dipole strength below 10 MeV is small in all Ca isotopes. Surprisingly, the proton and neutron transition densities of these low lying electric dipole states are in phase, which indicate isoscalar structure. We conclude that for the detailed understanding of the structure of excited nuclei e.g. the low lying and high lying electric dipole strength an approach like the present one is absolutely necessary.

KW - Low lying electric dipole strength and giant electric dipole resonances

KW - Microscopic theory

KW - Single-particle continuum

KW - Transition densities

UR - http://www.scopus.com/inward/record.url?scp=33947124442&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2007.01.069

DO - 10.1016/j.physletb.2007.01.069

M3 - Article

VL - 647

SP - 104

EP - 110

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

SN - 0370-2693

IS - 2-3

ER -