Spectral structure of the pygmy dipole resonance.

Authors :: Tonchev AP
Hammond SL
Kelley JH
Kwan E
Lenske H
Rusev G
Tornow W
Tsoneva N
Source :: Physical review letters [Phys Rev Lett] 2010 Feb 19; Vol. 104 (7), pp. 072501. Date of Electronic Publication: 2010 Feb 18.
Publication Year :: 2010
Abstract: High-sensitivity studies of E1 and M1 transitions observed in the reaction 138Ba(gamma,gamma{'}) at energies below the one-neutron separation energy have been performed using the nearly monoenergetic and 100% linearly polarized photon beams of the HIgammaS facility. The electric dipole character of the so-called "pygmy" dipole resonance was experimentally verified for excitations from 4.0 to 8.6 MeV. The fine structure of the M1 "spin-flip" mode was observed for the first time in N=82 nuclei.