Investigation of the electric dipole ( E 1) excitations in $$^{\mathrm {181}}$$ 181 Ta nucleus
- PDF / 657,333 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 15 Downloads / 151 Views
Regular Article - Theoretical Physics
Investigation of the electric dipole (E1) excitations in 181 Ta nucleus E. Tabar1, H. Yakut1, A. A. Kuliev2 , G. Ho¸sgör1,a , E. Kemah1, H. Quliyev1 1 2
Physics Department, Faculty of Science and Arts, Sakarya University, Sakarya, Turkey Azerbaijan National Academy of Aviation, Baku, Azerbaijan
Received: 20 July 2020 / Accepted: 8 October 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Communicated by Mark Caprio
Abstract E1 transition properties such as the reduced transition probabilities, excitation energies and photon– absorption cross-sections have been theoretically investigated for 181 Ta nucleus within the framework of Translational and Galileo Invariant-Quasiparticle Phonon Nuclear Model (TGI-QPNM). The model Hamiltonian includes the single-particle and the isovector dipole–dipole interaction terms along with the restoration forces. The strength of the isovector dipole–dipole interaction has been chosen to be χ = 500/A5/3 MeV · f m −2 . Theoretical calculations show that in addition to the M1 excitations, there is considerable amount of E1 transitions especially between 2.6– 3 MeV, which gives remarkable contribution to the fragmentation in the low-energy region of the dipole spectrum. Thus, the agreement between theory and experiment in terms of the fragmentation increases. Furthermore, the photon– absorption cross-sections in the Pigmy Dipole Resonance (PDR) region below the neutron separation energy (Sn ) is compatible with experimental data.
1 Introduction The understanding of the dipole response in atomic nuclei is one of the important way to solve nuclear structure puzzle. The history of dipole modes began with observation of a broad resonance in certain nuclei using mono-energetic photons produced in a Li ( p, γ ) reaction in 1937 by Bothe and Gentner [1] N. Bohr was firstly tried to explain the cross-sections of this high-energy resonance lying 9–20 MeV energy range, [2], but an interpretation close to modern explanation came from the seminal work of Migdal in 1944. He explained the enhanced cross section as a dipole oscillation of the protons against the neutrons [3]. Shortly after this explanation, the shape of the resonance was established from the experiments carried out by Baldwin and Klaiber, where they a e-mail:
were managed to measure systematically photofission crosssections of some heavy elements using bremsstrahlung rays from a 100-MeV betatron [4]. As the measured cross-section of the resonance exhausts a significant part of the energy weighted (TRK) sum rule, it is generally denoted as Giant Dipole Resonance (GDR) [5]. Goldhaber and Teller macroscopically interpreted it as vibration of the rigid sphere of neutrons against the rigid sphere of protons [6,7]. It is well established that E1 strengths in GDR region K = 0 and K = ±1 branches split in deformed nuclei due to groundstate deformation, while those are identical for spherical nuclei [8]. As a result of using gamma-rays after thermal neutro
Data Loading...
