Single-particle Scheme Research Articles

(d, p) and (d, t) Reaction Studies of the Actinide Elements. I.U235

Levels of the nucleus ${\mathrm{U}}^{235}$, populated in the reactions ${\mathrm{U}}^{234}(d, p){\mathrm{U}}^{235}$ and ${\mathrm{U}}^{236}(d, t){\mathrm{U}}^{235}$ induced by 12-MeV deuterons from the Argonne tandem Van de Graaff, were analyzed with a magnetic spectrograph. Most of the observed levels were identified as members of rotational bands built on the single-particle states of a deformed central field. The level assignments were made on the basis of relative populations of presumed members of each rotational band, ratios of the cross sections at 90\ifmmode^\circ\else\textdegree\fi{} and 140\ifmmode^\circ\else\textdegree\fi{}, and $\frac{(d, p)}{(d, t)}$ cross-section ratios. Pairing effects were calculated for the observed spectrum, and a single-particle scheme was extracted from the data. This single-particle scheme was compared with the calculations of Nilsson and Rost. Levels not predicted on the basis of the single-particle models were observed at excitations as low as 700 keV. Some of these levels, presumably vibrational excitations, were found to have cross sections comparable to those of single-particle states.

Einzelteilchen-Niveaus in einem deformierten energieabh�ngigen Kernpotential

The nucleon wave functions and energy eigenvalues in a spheroidal potential well of Woods-Saxon type are calculated approximately by diagonalizing the Hamiltonian in a finite subspace of Hilbertspace. The depth of the potential well is made energy dependent to account for the nonlocality of nucleon-nucleus interaction. With the pairing theory of residual interaction taken into consideration these results are used to determine nuclear deformation, energy of single-particle excited states, and an estimate of magnetic moments of nuclei with mass number about 177. Several methods are applied to calculate the equilibrium deformation. They all yield nearly identical results. The experimentally given low-energy spectra of odd-A nuclei, however, could not be reproduced satisfactorily. Some pronounced discrepancy between calculated and measured magnetic moments as already observed byMottelson andNilsson could not be reduced, either, though in other cases there is considerable improvement to their results. When comparing the structure of the calculated single particle scheme with the observed sequence of nuclear levels one is led to the conclusion that better agreement will be found for a somewhat different deformation: the nuclear shape will be given by a spheroid necked in to some degree by the equator and thickened at the ends.

V-Strap Model forPS-PSScattering and the Stabilities of Various Solutions

We examine the V(JP=1-)-strap model of the scattering between the mass-degenerated PS mesons, in connection with the possible dynamical origin for the symmetry of strong interaction. If we assume only the charge independence and the conservation of strangeness, we have six isomultiplets (and their antiparticles) of vector mesons composed of various pair of PS mesons π, K and η. It is known that there are many sets (schemes), besides the octet, of V mesons out of the six mentioned above, which equally satisfy the V-strap self-consistent equations. Thus we need further conditions in addition to the requirement of the self-consistency to pick out a physically acceptable solution among otherwise allowed solutions. The additional condition considered here is the stability of the solutions for the small variation of the input mass, the mass of exchanging V mesons. It is shown that the octet (ρ, M, ω) and the three single particle scheme (ρ), (M), (ρ') are stable, but all other “irreducible” schemes are unstable under the stability condition mentioned above.