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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 (Institutionen för fundamental fysik, Subatomär fysik) ; 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 (Institutionen för fundamental fysik, Subatomär fysik) ; 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
Nuclear Structure and Dynamics '09 (0094-243X). Vol. 1165 (2009), p. 181-184 461.
[Konferensbidrag, refereegranskat]

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.

Nyckelord: sn-130,sn-132, ni-58,ni-68, pygmy dipole resonance, giant dipole resonance, electromagnetic excitation, neutron skin, symmetry energy, n=82 nuclei, energy, modes


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Denna post skapades 2010-03-08. Senast ändrad 2015-03-30.
CPL Pubid: 117505

 

Institutioner (Chalmers)

Institutionen för fundamental fysik, Subatomär fysik (2005-2013)

Ämnesområden

Mellanenergifysik

Chalmers infrastruktur