Study of the high lying electric dipole excitations in Odd-A ^153–159Eu isotopes

Abstract

In this paper, we have studied the electric dipole (E1) transitions in odd-mass 153–159Eu nuclei within Translational+Galilean Invariant Quasiparticle Phonon Nuclear Model (TGI-QPNM). Within the scope, the Giant and Pygmy Dipole Resonances (GDR and PDR) have been investigated in the energy range of 5–20 MeV. The numerical results show that the contribution of PDR and GDR to the total E1 strength is 2% and 98%, respectively. It has been found that the TGI-QPNM predicts the double hump structure and that the agreement between theoretical results and the existing experimental data is perfect, especially near the neutron binding energy Sn and the first hump of the GDR. Also the comparison of the theoretical results and the existing experimental data shows reasonable agreement for the integrated moments of the cross-sections in the GDR region. We can also deduce from the structure analysis of excited states the studied isotopes, that the GDR states can be considered to be more collective than the PDR states.

Dipole responses in γ−soft 124–134Xe in the spectroscopic energy region

“…In the employed model, by selecting suitable separable, effective isoscalar and isovector forces, the rotational invariance (RI-) was restored to describe the magnetic dipole (M1) excitations [17,[37][38][39], as well as the translational and Galilean invariance (TGI-) [9,19] for calculating the E1 excitations. This model also satisfactorily described the fragmentation of electric and magnetic dipole strength in well-deformed [40][41][42][43][44][45][46][47][48][49][50][51], transitional, and γ-soft [9,10,13,19] nuclei, as well as the giant dipole resonance and pygmy dipole resonance [40, 42-44, 46, 49, 50] in deformed nuclei [17, 37, 40-48, 52, 53].…”

Theoretical description of pygmy and giant dipole resonances in 237Np

“…The two terms in equation (2) can be expressed as restoring h 0 and h D interactions, thus representing the translational and Galilean invariances, respectively [42][43][44][45].…”

“…The primary purpose of this study is to theoretically determine, for the first time, how the E1 dipole resonances lying in the high-energy region behave for the 237 Np nucleus. In our previous studies, we successfully theoretically predicted the E1 dipole strength by using the TGI-QPNM method with a separable isovector dipole-dipole interaction based on the mean-field in odd-A deformed nuclei [42][43][44][45]. Once again, the Rotational Invariant (RI)-QPNM for theoretically describing the low-lying M1 excitations was successfully applied to oddmass deformed nuclei in our past studies [48].…”

“…Microscopic approximations play an essential role in satisfactorily describing the dipole excitations in the different energy regions mentioned above [36][37][38][39][40][41][42][43][44][45][46][47]. Random Phase Approximation (RPA) and Quasiparticle-RPA (QRPA) have been widely used to explain the properties of low-lying states and pygmy/giant dipole resonances.…”

Microscopic calculation of the electromagnetic dipole strength for 239,243Pu isotopes

“…For this study, we applied a quasiparticle phonon nuclear model (QPNM) approach based on rotational invariant (RI-), translational, and Galilean invariant (TGI-) requirements, and this allowed us to analyze the spectral properties of the excited J π =1 − and 1 + states within the same excitation energy region [62][63][64][65][66][67][68][69][70][71]. This extended version of the QPNM [72] formalism considers transitions of the E1 and M1 types.…”