[en] Elastic scattering of 27.2 MeV α particles on ⁴⁰Ca has been investigated. Differential cross sections have been measured in the angular range from 10 deg to 175 deg in the lab. system. The theoretical analysis has proceeded from the proposition that the results of a calculation based on the optical model in the range of small angles (less than 20 deg for ⁴⁰Ca) are independent of parameters and shape of the potential employed. Elastic scattering of α particles at angles up to 50 deg has been calculated using three sets of the optical potential parameters in the energy range 23.37-28.92 MeV. In the range of small angles a rather similar behaviour of the calculated curves can be observed whereas in the range of medium and large angles these curves behave very differently. The success in the reproduction of the angular distributions for the entire energy range is indicative of the weak energy dependence of the optical potential parameters for ⁴⁰Ca. It can be stated that the optical model may be used successfully for the interpretation of the elastic scattering of medium-energy α particles on ⁴⁰Ca

[en] The Hartree-Fock method with nucleon-nucleon interaction similar to the Skyrme forces is used to calculate the differences between neutron and proton densities of nuclei and the neutron excess distribution for N>Z nuclei. The results are compared to the results of other calculations and to the experimental data on electron scattering by strongly interacting particles showing that the neutron radius exceeds the proton radius

[en] Ytterbium isotopes with mass numbers 153-158 have been produced at the ISOLDE on-line mass separator facility. The α-decay energies, half-lives and α-branching ratios were measured. The previously unknown nuclide, ¹⁵³Yb, was found to decay with a half-life of 4.0+-0.5 sec. Alpha emission was observed for the first time from ¹⁵⁸Yb. For the remaining isotopes, earlier mass assignments were confirmed. The α-decay properties of nuclides that were found as daughters of the ytterbium isotopes were also investigated. Alpha-branching ratios were derived for the nuclides ¹⁵³Tm, ¹⁵²¹⁵³Er, ¹⁵²Ho and ¹⁵⁰Dy. The systematics of α-energies and α-widths are discussed. (Auth.)

[en] The two-particle pick-up reaction ⁵⁸Ni(d, α γ)⁵⁶Co at Esub(d) = 7.0 MeV was used to determine mean lifetimes of levels in ⁵⁶Co up to 2.73 MeV excitation energy by the Doppler shift attenuation method. γ-rays were observed in a 43 cm³ Ge(Li)-detector at 90⁰ to the beam axis in coincidence with α-particles detected in two 200 μm-silicon surface barrier detectors at THETAsub(α) = +- 55%. Mean lifetimes for 10 levels in ⁵⁶Co and two lifetime limits have been obtained using F(tau)-curves calculated with the Winterbon theory. The experimental results are compared with the predictions of recent shell model calculations. (orig.)

[en] The method of hyperspherical functions (HSFM) is applied to calculate nuclear formfactors. The method can be used for calculations in the HSFM lower approximation as well as for consideration of higher harmonics. The HSFM wave functions invariant under translations are used. Contributions from separate shells to the nuclear form factors are studied. Some particular examples are considered

[en] The experimental evidence supporting the double humped character of the fission barrier in actinide nuclei is reviewed and compared to theoretical predications. The discussion covers the properties of spontaneously fissioning isomers, intermediate structure in fission cross sections, the systematics of fission barrier heights, and the implications of a possible octupole deformation at the second barrier for fragment mass distributions. (author)

No abstract available

[en] The (π^-,2n) reaction on ⁴⁰Ca has been investigated via the determination of the momenta for the two neutrons emitted simultaneously following the absorption of π^-. The ³⁸K excitation spectrum, opening-angle distributions, and recoil momentum distribution are determined. The direct mechanism is established for transitions to the lower part of the ³⁸K excitation spectrum. (orig.)

[en] Experimental and theoretical investigations have been fullifilled to verify the optical-statistical model of nuclear reactions. The inelastic scattering of neutrons by ⁴⁸Ti, ⁵⁶Fe, ⁵⁸Ni, ⁹⁴Zr and ⁹²Zr nuclei was studied using a Ge(Li) gamma spectrometer installed at 90 deg with respect to the incident beam of 1.57-2.80 MeV neutrons. The yield of gamma rays has been analyzed in terms of the spherical optical model with the account of formation and decay of compound nuclei assuming energy level width fluctuations and dependence of the fluctuations and depend ence of the fluctuations on Esub(n) and nucleon composition of the nuclei. For each nucleus in question parameters of the optical potential were chosen by the agreement observed between available experimental and theoretical data on neutron elastic scattering. The number of degrees of freedom ν in the X²-distribution of neutron widths in a compound nucleus was treated as a statistical parameter. The assumed hypothesis of ν dependence on Esub(n) has proved valid

No abstract available