Article,
Study of the pygmy dipole resonance in Mo-94 using the (alpha, alpha ` gamma) coincidence technique
Nuclear Physics A, (May 2013)
DOI: 10.1016/j.nuclphysa.2013.02.018
Abstract
The (alpha, alpha' gamma) reaction at E-alpha = 136 MeV was used to
study the electric dipole response in the open-shell vibrational nucleus
Mo-94 below the neutron-separation threshold. The coincidence experiment
has been performed at the Kernfysisch Versneller Instituut in Groningen,
The Netherlands, exploiting the Big-Bite Spectrometer and an array of
large volume High-Purity Germanium (HPGe) detectors. Due to the
excellent energy resolution and high selectivity to transitions stemming
from the pygmy dipole resonance, singles alpha-scattering cross sections
could be determined for individual electric dipole excitations between 4
and 8 MeV. For three of the excited low-lying J(pi) = 1(-) states in
Mo-94 a gamma-decay branch into the J(pi) = 2(1)(+) state could be
observed.
The experiment extends the systematic studies of the pygmy dipole
resonance by real-photon scattering (gamma, gamma') experiments and
(alpha, alpha' gamma) experiments. Recently, a (gamma, gamma')
experiment on Mo-94 was performed at the Darmstadt High-Intensity Photon
Setup at the S-DALINAC in Darmstadt, Germany, permitting the comparison
of B(E1)up arrow strength distribution and alpha-scattering cross
sections. (C) 2013 Elsevier B.V. All rights reserved.
