L.A. Malov

Single-particle energies and wave functions for the saxon-woods potential and the levels of odd-A nuclei in the actinide region

Abstract The Saxon-Woods single-particle energies and wave functions are given for the description of deformed nuclei in the region 234 ≦ A ≦ 250. The energies and the wave functions for the non-rotational states of odd- A nuclei are calculated taking into account the interaction of quasiparticles with phonons. The latter is found to be more important for nuclei in the actinide region than in the rare-earth one. A rather good description of the energies of low-lying non-rotational states in 235 U, 237 U, 241 Pu, 245 Cm, 247 Cm, 249 Cm, 237 Np, 241 Am and 249 Bk is obtained. The calculated Saxon-Woods single-particle energies and wave functions may serve as a basis for calculating various characteristics of nuclei in the actinide region.

Fragmentation of single-particle states and neutron strength functions in deformed nuclei

Abstract The fragmentation of single-particle states and the neutron strength functions in odd- N deformed nuclei are studied in the framework of a model based on the quasi-particle-phonon interaction. The dependence of the fragmentation on the positions of the single-particle levels with respect to the Fermi level is studied. It is shown that in the distribution of the single-particle strength, alongside a large maximum there appear local maxima, and the distribution itself has a long tail towards high excitation energies. The averaged neutron strength functions are determined without calculating the energies and wave functions of each state. The dependence of neutron strength functions on the excitation energy is investigated for transfer reactions of the type (d, p) and (d, t). The s-, p- and d-wave neutron strength functions are calculated for many deformed nuclei at the neutron binding energy B n . They are in satisfactory agreement with the corresponding experimental data.

A model for describing the structure of highly excited states in deformed nuclei (I)

A model for describing states of intermediate and high excitation energy in deformed nuclei which is based on the quasiparticle-phonon interaction is suggested. A secular equation for determining the energy and the wave functions is obtained by means of the variational principle. The neglect of the non-coherent terms leads to the appearance of extraneous states. A method for eliminating them is developed. On the basis of the calculations performed for 239U, at an energy close to the neutron binding energy, the average spacing between the 12+ states is found to be 33 eV which is twice as large as the experimental value. The magnitude of the one-quasiparticle components is between 10−7 and 10−11. The increase of the density of the states with increasing excitation energy is demonstrated. It is concluded that the quasiparticlephonon interaction is responsible for both the complication of the state structure with increasing excitation energy and the fragmentation of the one-particle states over many nuclear levels.

Semi-microscopic description of the density of excited states in deformed nuclei

Abstract A semi-microscopic method of calculating the density of states of intermediate and high excitation energies in deformed nuclei is suggested. The method is used to calculate the densities of the states of 31 nuclei of the rare-earth and transuranium region at the neutron binding energy. The results of calculations are in satisfactory agreement with experiment. The difference in the density of states of doubly even and odd-A nuclei is correctly described. The effect of nuclear vibrations on the density is studied. The dependence of the density on the excitation energy and the quantum number K is investigated.

Semimicroscopic description of giant octupole resonances in deformed nuclei

Abstract The strength functions b(E3, ω) are calculated, and the positions and widths of giant octupole resonances in deformed nuclei are found. It is shown that the giant octupole isoscalar resonances have energies (19–20) MeV for the rare-earth nuclei and (17–18) MeV for the actinides and the widths (5–7) MeV. The energies of the giant octupole isovector resonances are defined by the value of the isovector constant κ(3)1.

Study of 153Sm via the 154Sm(p,d) reaction

Abstract Excited states in the 153 Sm nucleus have been investigated via the (p,d) reaction performed with a good resolution. About 170 levels were observed below 2.2 MeV excitation energy; for most of them the l-transfer value could be assigned. Distorted wave calculations have been performed and discussed. The 153 Sm is already rather deformed, and can be described in terms of the Nilsson model. Levels below 0.5 MeV were identified as members of rotational bands based on the Nilsson orbitals. The strength distributions have been described within the Quasiparticle Phonon Model.

Level density for doubly odd deformed nuclei

Abstract The level density for doubly odd deformed nuclei near B n is calculated within the framework of the semi-microscopic approach. The calculated values are found to be in good agreement with the experimental ones. It is shown that for the I ⩾ 1 states it is important to take into account rotational motion.