Pygmy Dipole Strength in Exotic Nuclei and the Equation of State

A. Klimkiewicz; N. Paar; P. Adrich; M. Fallot; T. Le Bleis; D. Rossi; K. Boretzky; T. Aumann; H. Alvarez-Pol; F. Aksouh; J. Benlliure; T. Berg; M. Boehmer; E. Casarejos; M. Chartier; A. Chatillon; D. Cortina-Gil; U. D. Pramanik; T. W. Elze; H. Emling; O. Ershova; B. Fernando-Dominguez; H. Geissel; A. Gorska; M. Heil; M. Hellstrom; Håkan T Johansson; K. L. Jones; A. Junghans; O. Kiselev; J. V. Kratz; R. Kulessa; N. Kurz; M. Labiche; R. Lemmon; Y. Litvinov; K. Mahata; P. Maierbeck; Thomas Nilsson; C. Nociforo; R. Palit; S. Paschalis; R. Plag; R. Reifarth; H. Simon; K. Summerer; G. Surowka; D. Vretenar; A. Wagner; W. Walus; H. Weick; M. Winkler

Pygmy Dipole Strength in Exotic Nuclei and the Equation of State
Paper in proceeding, 2009

A concentration of dipole strength at energies below the giant dipole resonance was observed in neutron-rich nuclei around Sn-132 in an experiment using the FRS-LAND setup. This so-called "pygmy" dipole strength can be related to the parameters of the symmetry energy and to the neutron skin thickness on the grounds of a relativistic quasiparticle random-phase approximation. Using this ansatz and the experimental findings for Sn-130 and 132 Sri, we derive a value of the symmetry energy pressure of (p) over bar (0) = 2.2 +/- 0.5 MeV/fm(3). Neutron skin thicknesses of R-n-R-p = 0.23 +/- 0.03 fm and 0.24 +/- 0.03 fm for Sn-130 and Sn-132, respectively, have been determined. Preliminary results on Ni-68 from a similar experiment using an improved setup indicate an enhanced cross section at low energies, while the results for Ni-58 are in accordance with results from photoabsorption measurements.

n=82 nuclei

electromagnetic excitation

giant dipole resonance

sn-132

ni-68

neutron skin

ni-58

modes

symmetry energy

energy

pygmy dipole resonance

sn-130

Author

A. Klimkiewicz

N. Paar

P. Adrich

M. Fallot

T. Le Bleis

D. Rossi

K. Boretzky

T. Aumann

H. Alvarez-Pol

F. Aksouh

J. Benlliure

T. Berg

M. Boehmer

E. Casarejos

M. Chartier

A. Chatillon

D. Cortina-Gil

U. D. Pramanik

T. W. Elze

H. Emling

O. Ershova

B. Fernando-Dominguez

H. Geissel

A. Gorska

M. Heil

M. Hellstrom

Håkan T Johansson

Chalmers, Applied Physics, Subatomic Physics

Other publications Research

K. L. Jones

A. Junghans

O. Kiselev

J. V. Kratz

R. Kulessa

N. Kurz

M. Labiche

R. Lemmon

Y. Litvinov

K. Mahata

P. Maierbeck

Thomas Nilsson