We construct a set of separable potentials for the nucleon-nucleon, pion-nucleon, and pion-pion subsystem for all partial waves with angular momentum L<eq2 within the framework of the relativistic two-body Kadyshevski equation. These interactions serve as input for the relativistic three-body equations proposed by the authors as well as for the three-body formalism derived by Vinogradov.

The E2 nuclear resonance effect has been studied in the pionic atoms of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{104}{}_{}{}^{}\mathrm{Ru}$, ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$, ${}_{}{}^{111}{}_{}{}^{}$,112Cd, ${}_{}{}^{125}{}_{}{}^{}\mathrm{Te}$, and ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$. The experimental values of the attenuation for ${}_{}{}^{104}{}_{}{}^{}\mathrm{Ru}$, ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$, and ${}_{}{}^{111}{}_{}{}^{}$,112Cd agree with the predictions of the theoretical model of Leon. Using the more detailed calculations of Dubach et al., one obtains closer agreement between theory and experiment for ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ although in the latter case the difference is still more than two standard deviations. Although the same levels are mixed in ${}_{}{}^{125}{}_{}{}^{}\mathrm{Te}$ as in ${}_{}{}^{104}{}_{}{}^{}\mathrm{Ru}$ and ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$, the theoretical prediction of the attenuation by Leon is nearly two standard deviations greater than the experimental value. A more precise energy for the second ${\mathrm{}(5/2)\mathrm{}}^{+}$ state in ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ is deduced.

The spin dependence of quasi-elastic proton-nucleus scattering is studied using Glauber’s eikonal multiple scattering theory, which is extended to include multiple knockout collisions as well as the full spin dependence of the NN amplitudes. Calculations of the cross section $d^2$σ/dΩ dp and spin observables DNN, DLL, DSS, DSL, DLS, Ay are presented and compared to data for $d^2$σ/dΩ dp and Ay from inclusive (p,p’) experiments on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at $T_{\mathrm{lab}=800\mathrm{}}$ MeV. The main feature seen is a drop in the spin observables in the kinematic region where two nucleon knockout dominates the cross section. As an initial study of the contribution of quasi-free Δ production to the inclusive cross section, multiple scattering theory is used to normalize a plane-wave impulse approximation calculation of $d^2$σ/dΩ dp for p${+}^{12}$C→p+π${+}^{12}$${\mathrm{C}}^{\mathrm{*}}$. .AE

A Lorentz-invariant representation for NN scattering amplitudes is derived. The general NN representation assuming parity invariance involves 128 amplitudes for a given isospin, all but 8 of which involve negative energy projection operators and therefore possess vanishing matrix elements in positive energy states. When charge symmetry and time-reversal invariance are taken into account, the number of independent amplitudes reduces to 56 for a given isospin, and this number further reduces to 44 when all particles are on mass shell. Relativistic meson theory is used to determine the negative energy terms since they cannot be determined from physical scattering data. The formalism is developed to determine the complete set of invariant amplitudes starting from partial wave t-matrix elements which arise from solving quasipotential equations for NN scattering.

Using diagrammatic techniques we have obtained a new operator for the process p(γ,${\mathrm{K}}^{+}$)${\mathrm{\Lambda }}^0$ which includes the Born terms in addition to resonances in the s and u channel near threshold. The coupling constants are obtained by a least squares fit to cross section and polarization data for photon energies from threshold through 1400 MeV. We find a number of changes from the earlier operator obtained by Thom about twenty years ago when less data were available. To aid in comparing this operator to other work, we give its multipole decomposition in the center of mass frame, and to aid in its use in nuclear physics we write out the operator in a frame fixed in the nucleus and, further, take the nonrelativistic limit of the operator as Blomqvist and Laget did for the pion photoproduction case. Finally, we discuss the validity of the nonrelativistic limit of this operator.

In the present paper we extend earlier work on spin-dominated transitions using a plane wave formalism to a full distorted wave treatment. We perform a distorted wave calculation using a relativistic approach to nucleon-nucleus inelastic scattering. We focus on the $1^{+}$, T=0 transition in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ using 500 MeV protons with special emphasis on spin observables. We obtain sizable effects for spin observable differences without invoking exchange processes.

The beta-delayed proton emissions of the odd-Z, $T_z$=-(3/2) nuclei ${}_{}{}^{27}{}_{}{}^{}\mathrm{P}$ and ${}_{}{}^{31}{}_{}{}^{}\mathrm{Cl}$ have been studied. This work represents the first observation of the decay of ${}_{}{}^{27}{}_{}{}^{}\mathrm{P}$, yielding a half-life of 260±80 ms, and completes the series of beta-delayed proton emitters with $T_z$=-(3/2) in the sd shell. Several new proton groups were attributed to the decay of ${}_{}{}^{31}{}_{}{}^{}\mathrm{Cl}$; their half-lives are consistent with a previous observation. The estimated logft values of the observed transitions for both ${}_{}{}^{27}{}_{}{}^{}\mathrm{P}$ and ${}_{}{}^{31}{}_{}{}^{}\mathrm{Cl}$ are consistent with clustering of the beta strength above the isobaric analog states in the daughter nuclei as predicted by a complete (1s,0d)-space shell-model calculation. The observed half-lives are in good agreement with the shell-model predictions which include a quenching of the Gamow-Teller strength by a factor of 0.6, in accordance with earlier observations.

The magnetic hyperfine splitting frequencies ${\nu }_M$=‖g${\mu }_{\mathrm{N}}$$B_{\mathrm{HF}}$/h‖ of ${}_{}{}^{99}{}_{}{}^{}\mathrm{Rh}_{}^{\mathrm{m}}{}_{}{}^{}$ ($T_{1/2}$=4.7 h; $I^{\pi }$${=(9/2)\mathrm{}}^{+}$) and ${}_{}{}^{101}{}_{}{}^{}\mathrm{Rh}_{}^{\mathrm{m}}{}_{}{}^{}$ ($T_{1/2}$=4.3 d; $I^{\pi }$${=(9/2)\mathrm{}}^{+}$) in Fe were measured with nuclear magnetic resonance on oriented nuclei as 534.28(5) MHz and 516.10(5) MHz, respectively. With the hyperfine field $B_{\mathrm{HF}}$(RhFe)=-556.6(1.2) kG the g factors are deduced to be ${}_{}{}^{99}{}_{}{}^{}\mathrm{Rh}_{}^{\mathrm{m}}{}_{}{}^{}$: ‖g‖=1.2595(27); ${}_{}{}^{101}{}_{}{}^{}\mathrm{Rh}_{}^{\mathrm{m}}{}_{}{}^{}$:‖g‖=1.2167(26). The g factors are discussed in the framework of the systematics of π$g_{9/2}$ states. The new data give strong evidence that the ${\mathrm{}(7/2)\mathrm{}}^{+}$ states appearing in Rh at rather low excitation energies cannot be described by a & configuration as adopted up to now. In addition, the hyperfine splitting frequency of ${}_{}{}^{97}{}_{}{}^{}\mathrm{Ru}$ in Fe was remeasured to be 117.58(2) MHz. With the hyperfine field $B_{\mathrm{HF}}$(RuFe)=-489.6(4.0) kG, the g factor of ${\mathrm{}(5/2)\mathrm{}}^{+}$ ${}_{}{}^{97}{}_{}{}^{}\mathrm{Ru}$ is determined to be ‖g‖=0.315(3). The resonance shifts of ${}_{}{}^{52}{}_{}{}^{}\mathrm{Mn}$, ${}_{}{}^{97}{}_{}{}^{}\mathrm{Ru}$, ${}_{}{}^{99}{}_{}{}^{}\mathrm{Rh}_{}^{\mathrm{m}}{}_{}{}^{}$, and ${}_{}{}^{101}{}_{}{}^{}\mathrm{Rh}_{}^{\mathrm{m}}{}_{}{}^{}$ in Fe were measured in external magnetic fields up to 10 kG. The relative Knight shifts are discussed.

Allowed isospin-hindered positron decay from polarized ${}_{}{}^{56}{}_{}{}^{}\mathrm{Co}$ has been studied using a β-particle detection assembly mounted on a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$${/}^4$He dilution refrigerator, and the asymmetry parameter was found to be $A_{\beta }$=+0.359±0.009. Assuming the standard V-A weak interaction theory and time-reversal invariance, the Fermi to Gamow-Teller interference ratio, y=$C_V$$M_F$/$C_A$$M_{\mathrm{GT}}$, is then -0.091±0.005. Our high precision result is in reasonable agreement with most of the previously reported results, but is in serious disagreement with an earlier measurement by Pingot, who found y=+0.002±0.004.

Baryon-number-violating (ΔB=2) processes are predicted by a variety of grand (or partially) unified theories of the fundamental interactions. In this paper we explore the double proton decay inside nuclei. We calculate the width Γ for the associated exotic nuclear decay and, by exploiting the experimental data on nuclear stability, we are able to set an upper bound on the coupling constant K of the corresponding effective Lagrangian. This, in turn, can be converted into a lower bound for the time of oscillation of hydrogen into antihydrogen. The latter turns out to be much more stringent than the one inferred from astrophysical observations.

An alternative interpretation of the second excited $K^{\pi }$${=0\mathrm{}}^{+}$ band in rare earth nuclei, as a mixed-symmetry state in the neutron-proton interacting boson model, is compared with the conventional interpretation as a two-quasiparticle band. It is shown that, on the basis of electromagnetic decay probabilities and particle transfer amplitudes alone, it is difficult to discriminate between the two interpretations. Only on the level of form factors and transition densities do major differences occur.

The exact treatment of fermion systems by Monte Carlo methods has proved to be difficult. We present a new method based on the concept of a ‘‘mirror potential,’’ which is a many-body potential that forces the Monte Carlo iteration to have a stable antisymmetric component. The potential may be determined from the wave function and, within the framework of Green’s function Monte Carlo, from the random walk whose density converges to the wave function. In certain limits, the method reduces to the fixed node approximation and to transient estimation, so that it subsumes both of them. As a further consequence it offers an approximation analogous to fixed node for treating systems with noncentral forces. The method may prove to be a general one for treating random walkers with nonpositive or complex weights. In support of that we exhibit a successful calculation of a one-dimensional excited state. In this paper we explore the alternative in which the mirror potential is obtained from trial wave functions. This yields an approximation scheme that proves to be accurate in the experiments described here. We present results for a model problem in which four neutrons interact by a spin-independent potential, and compare the results with those of the fixed node method, and the method of transient estimation.

Numerical calculations based on the continuum shell model with a unified description of long-lived and short-lived resonance states are performed for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. The results show that the spectroscopic properties of the individual states depend on the degree of overlapping with other resonance states.

The boson expansion theory of Kishimoto and Tamura is applied to a single-j shell model. It is shown that this theory is quite accurate, giving results that agree very closely with those of the exact fermion calculations. The fast convergence of the boson expansion is also demonstrated. A critical discussion is then made of an earlier paper by Arima, in which he stated that the Kishimoto-Tamura theory gives rise to very poor numerical results. The source of the trouble encountered by Arima is unmasked.

The problem of the quenching of transition strength to stretched states is here addressed. A rotational Hamiltonian is used, including a Coriolis term and the Nilsson intrinsic Hamiltonian. The Coriolis term mixes different K bands. We consider the $6^{\mathrm{-}}$ states in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. A significant amount of quenching is obtained. Part of this is due to the fact that the summed strength in the rotational model is equal, in single particle units, to the percent occupancy of the $d_{5/2}$ shell, and hence is less than the single particle value. The other part is due to the fact that there is a large fragmentation of strength to many states. To remove the degeneracy between the isoscalar and isovector states, a schematic residual interaction of the form M(6)⋅M(6) is introduced and evaluated in the intrinsic state.

We measured upper limits for the production of superheavy elements from the compound nucleus reaction ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$${+}^{254}$Es. This combination permits the closest approach to the predicted island of stability at the 184 closed-neutron shell of any practical fusion reaction. We used aqueous and gas-phase separations to isolate superheavy element fractions within an hour from the end of the bombardments. In these experiments we did not observe superheavy elements above a limit of 3×${10}^{\mathrm{-}31}$ ${\mathrm{cm}}^2$ for spontaneous-fission half-lives from fractions of a day to a few months.

The ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(d,p${)}^{15}$C reaction has been used to search for $d_{3/2}$ strength in the particle-unbound region of ${}_{}{}^{15}{}_{}{}^{}\mathrm{C}$ where the 1p-2h $J^{\pi }$${\mathrm{}(3/2)\mathrm{}}^{+}$ state is expected to lie. Proton spectra have been obtained over the angular range 15°–110° with vector-polarized incident deuterons of energy 16 MeV. Two ${\mathrm{}(3/2)\mathrm{}}^{+}$ levels, one broad (Γ∼1.8 MeV) and one relatively narrow (Γ=64 keV), are observed at excitation energies of 4.78 and 5.81 MeV, respectively. These states can be identified with the 1p-2h and 3p-4h ${\mathrm{}(3/2)\mathrm{}}^{+}$ levels predicted by shell-model calculations. The level parameters were extracted using a method suggested by Huby and Kelvin. The combined strength of the two states is approximately 50% of the single-particle strength.

The neutron-deuteron elastic scattering cross section was measured at 90° and 166° center of mass, at 31, 61, and 76 MeV. The charge exchange reaction ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(n,p)nn was measured at 7° lab for the same energies; the ratio of the latter to the neutron-proton elastic scattering was inferred.

We show that the existence of F-spin multiplets of nuclei can be understood in terms of an embedding into U(12). With this alternative view of F-spin multiplets some of their properties are clearly established.

Volume integrals of central optical potentials for scattering of deuterons, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and α particles from nuclei in the Fe-Ni region are discussed. The relative deviations of volume integrals of real central potentials for those estimated by nucleon-nucleus potentials are about -0.19, -0.25, and -0.28 for deuterons, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and α particles, respectively, at the bombarding energy of 10–30 MeV/nucleon and become negligibly small values at 70–100 MeV/nucleon region. Also the systematic behavior of volume integrals for imaginary potentials is presented.