Measurement of the Dipole and Electric Quadrupole Strength Distributions up to 10 MeV in the Doubly Magic Nuclei40Caand48Ca

Abstract

The doubly magic nuclei 40Ca and 48Ca have been studied in high resolution photon scattering experiments. We have derived absolute dipole and quadrupole excitation strengths up to 10 MeV. Evidence was found for a two-phonon quadrupole-octupole state in 48Ca. At higher energies in contrast to 40Ca, a concentration of dipole strength is observed in 48Ca which is discussed in terms of a pygmy resonance originating from the large neutron excess.

Decay of quadrupole-octupole1−states inCa40andCe140Derya1, Tsoneva2, Aumann3 et al. 2016Phys. Rev. CSelf Cite12120View full textAdd to dashboardCite

“…Low-lying E1 excitations have been studied systematically in 40 Ca, 44 Ca, and 48 Ca by means of NRF experiments [14,63,[75][76][77]. The doubly-magic N = Z nucleus 40 Ca exhibits almost no low-lying E1 strength, whereas 44 Ca and 48 Ca exhaust more and a similar amount of the Thomas-Reiche-Kuhn energy-weighted sum rule [76,77].…”

Relativistic quasiparticle random phase approximation in deformed nuclei

“…However, this would lead to divergent terms which can only be removed by a proper renormalization procedure. However, then one obtains a set of equations that can only be solved numerically [61] for finite nuclei, although an analytical solution for infinite nuclear matter can be found [38]. Numerical studies have shown that effects due to vacuum polarization can be as large as 20%-30%.…”

Structure of the isovector dipole resonance in neutron-rich 60 Ca nuclei and direct decay from pygmy resonance

“…These observations have forced the review of successful theoretical tools in nuclei around the β − stability valley [1,2,3,4].…”

“…INTRODUCTIONThe investigation of the nuclei lying far from the β − stability line has been an interesting and active field of the nuclear physics in the last two decades. In that region, a great number of exotic features are observed like halo/skin formation, intruders levels, new magic numbers and new kinds of collective excitation, the so-called soft and pygmy resonances.These observations have forced the review of successful theoretical tools in nuclei around the β − stability valley [1,2,3,4].The description of the microscopic structure of the exotic nuclei is a current topic of study and several recent works had the concern of describing the giant resonance (GR) in neutronrich nuclei. The main questions treated are the giant dipole resonance (GDR) behavior and the appearance of the pygmy dipole resonance (P DR) in a nucleus with large ratio of neutron to proton number (N/Z).…”