A measurement of the transverse beta spin polarization in a β-γ nuclear cascade gives information on time reversal invariance. Results from a preliminary experiment, using ${}_{}{}^{203}{}_{}{}^{}\mathrm{Hg}$ decay, are presented. The one previous experimental investigation, which used ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$ decay, is also reanalyzed in light of more recent information on Mott scattering polarization analysis. No time reversal violations are indicated in either experiment.

The nuclides ${}_{}{}^{52}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{52}{}_{}{}^{}\mathrm{Sc}$ have been produced by fragmentation of a uranium target with a 600 MeV proton beam. The subsequent β decays to the daughter nuclei ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Sc}$, and ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ti}$ have been studied by neutron and γ spectroscopy on sources obtained from on-line mass separation. β decay energies have been determined by β-γ coincidence spectroscopy. In addition to the short half-life of ${}_{}{}^{52}{}_{}{}^{}\mathrm{K}$ ($T_{1/2}$=110±30 ms), we attributed two different half-lives ($T_{1/2}$=4.6±0.3 s and $T_{1/2}$=8.2±0.2 s) to ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{52}{}_{}{}^{}\mathrm{Sc}$, respectively. A decay scheme has been established for ${}_{}{}^{52}{}_{}{}^{}\mathrm{K}$ involving five β branches to delayed neutron emitting states between 6.6 and 10.3 MeV and one β branch to a bound level at $E_x$=2.56 MeV. The ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ca}$ decay scheme accounts for β branches to four levels at 1.64, 2.75, 3.46, and 4.27 MeV for which the deduced logft values restrict the angular momentum and parity to $J^{\pi }$${=1\mathrm{}}^{+}$. For the ${}_{}{}^{52}{}_{}{}^{}\mathrm{Sc}$ ground state, strong β transitions to the $2^{+}$ (1.05 MeV) and the ($4^{+}$) (2.32 MeV) levels in ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ti}$ strongly favor a $J^{\pi }$${=3\mathrm{}}^{+}$ attribution. The measured $Q_{\beta }$ values for the ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ca}$ (5.7±0.2 MeV) and ${}_{}{}^{52}{}_{}{}^{}\mathrm{Sc}$ (8.02±0.25 MeV) decay are noticeably lower than expected from mass systematics. The energy level diagrams of ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Sc}$, and ${}_{}{}^{52}{}_{}{}^{}\mathrm{Ti}$ nuclei have been calculated in the framework of the shell model with a realistic interaction. Good agreement between theory and experiment is achieved as well for excitation energies as for mass excesses, assuring then the applicability of the theory to this region of nuclei far from stability.

A nuclear system is treated in which a forbidden beta decay leads to a state metastable against gamma-ray emission. Considering both the beta and isomeric transitions to be accelerated by an applied electromagnetic field, the rate equation for emission from the isomeric state is solved for the case where the nucleus is subjected to alternating episodes of field on and field off. There are important qualitative differences in the solution between the cases where enhancement of the beta transition rate dominates enhancement of the isomeric transition rate, and vice versa. Application is made to the example of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$.

The ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ nucleus is studied in a cluster picture with elementary alpha and triton particles as constituents. The relation of this elementary cluster model to the microscopic resonating group model is investigated. Within this cluster model various measurable quantities such as root mean square radii, transition probabilities, electromagnetic moments, and form factors are calculated and compared with the experiment. While the agreement for the electric quantities is surprisingly good, there are deviations for the magnetic ones.

The energies of highly deformed ‘‘four-particle–four-hole’’ states of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are calculated using Skyrme-like interactions. The J=0, 2, and 4 projected states are then considered. Deformed harmonic oscillator wave functions are used in which two oscillator lengths, $b_x$ and $b_0$, are allowed to vary. Both the energies and the stability of the states are studied as a function of the amount of fi- nite range energy in the interaction. Then a less restricted Hartree-Fock calculation is performed for the intrinsic state energies of both ‘‘four-particle–four-hole’’ states and ‘‘two-particle–two-hole’’ states. All the states considered come low enough in energy so as to be associated with the excited states of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in the 20 to 35 MeV range.

Backbending in even-even nuclei is fitted by mixing a ground state, β, or γ band described by the variable moment of inertia formula with a superband characterized by a constant moment of inertia and applying the standard band coupling formalism or constant interband interaction. Very accurate results are obtained in all cases. The interband interaction remains small, and its oscillatory behavior is well reproduced. The predictive power of the model is emphasized.

An iterative technique was used to solve the Faddeev equations, which determine the bound state of the triton, for the Reid soft core, Argonne $v_{14}$, super soft core (C), and de Tourreil-Rouben-Sprung (B) potential models. Separate solutions for each model were generated for 5, 9, 18, 26, and 34 three-body channels, the latter corresponding to all two-nucleon partial waves with J≤4. The results indicate that the odd partial waves do not contribute substantially to the energy, and that the J>4 partial waves probably contribute less than 10 keV. Coulomb energies, radii, and probability percentages of various wave function components were also calculated.

Antisymmetric α+${}^{14}$${\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ and α${+\mathrm{}}^{14}$C${(2\mathrm{}}_1^{+}$) wave functions are used in the generator coordinate formalism to investigate molecular properties of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ states. Quadrupole moments, rms radii, and reduced α widths of these states are calculated as well as reduced E1 and E2 transition probabilities between them. A number of molecular bands are found and analyzed. The assignment of experimental states to these bands is discussed. The alternating-parity band proposed by Gai et al. is interpreted as a fortuitous alignment of molecular states belonging to different bands.

The collapse of the three-nucleon ground state with separable two-body interactions of a Tabakin type is investigated. A simple scaling property of this phenomenon is derived. Moreover, an interpretation of the collapse is given in terms of the local equivalent of the Tabakin potential.

We present an approach to study the interplay between the surface and volume vibrations of nuclei with application to the isoscalar giant monopole resonance. The main ingredients are the well-known properties of the mean field and the curvatures of the liquid-drop energy surface. No specific form of a two-body force is assumed. The single-particle continuum is treated exactly. First results, obtained using a local Woods-Saxon potential, are discussed.

We have measured the ratio of resonance strengths for alpha capture on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ to the 4.77- and 5.16-MeV states of ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$. We find ωγ(4.77)/ωγ(5.16)=0.102± 0.004. When combined with the accepted value for ωγ(5.16) we determine the E2 strength of the 4.77- to 0.72-MeV level transition in ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ to be B(E2)=21±2 $e^2$${\mathrm{fm}}^4$, in agreement with a previous measurement when center-of-mass corrections are properly taken into account. The agreement between our result and Kurath’s interpretive model for ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ improves when collective effects in the 1p shell are included.

Recent work involving virtual excitation of a spin (3/2) baryon resonance is seen to contain two distinct problems. The Feynman propagator for spin (3/2) from the Rarita-Schwinger formalism has often been mistaken for its on-mass-shell limit. In nonrelativistic work the direct channel exchange of a Δ resonance is normally included, but with the exclusion of a term for the intermediate anti-Δ. It is shown that both of these terms are of equal importance in the resonance region for the case of nucleon Compton scattering.

Quantum mechanical inversion is used to obtain l-independent phase equivalent local potentials to microscopic nucleon-alpha potentials of Lassaut and Vinh Mau between $E_{\mathrm{lab}=15\mathrm{}}$ and 25 MeV. These potentials are compared with the corresponding local potentials obtained in the Perey-Saxon approximation.

We study the hypertriton using the formalism of hyperspherical harmonics, for spin-independent NN and NΛ two-body potentials of Gaussian shape. We use up to 19 Simonov harmonics for the Verma-Sural potential, and obtain a ground state energy 240 keV below their value of -2.35 MeV found for 9 Simonov harmonics. The partial waves are used to calculate various expectation values for the hypertriton. We readjust the strength of the ΛN potential to obtain agreement between the calculated energy and the experimental value.

The energy and density dependences of the effective t- and G-matrix tensor interactions have been analyzed. An apparent contradiction between experimental evidences on the effective isovector tensor force observed in nuclear structure and that observed in nuclear reactions has been explained.

We calculate the γ decay from the isoscalar and isovector giant quadrupole resonances in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ into the low-lying spectrum. Whereas the γ decay from the isoscalar giant quadrupole resonance into the first excited $3^{\mathrm{-}}$ state is very small, the corresponding transition from the isovector giant quadrupole resonance is strongly enhanced. According to preliminary calculations, these results hold rather generally for other heavy mass nuclei. We suggest using this property in experimental investigation of the isovector giant quadrupole resonance.

The radiative widths of two ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ levels were determined using photon scattering and self-absorption measurements. The results were ${\Gamma }_0$(6.917)=0.094±0.004 eV and ${\Gamma }_0$(7.117)=0.054±0.004 eV. The effective temperature $T_e$ of the O atom in a water target is calculated by accounting for the effect of the zero-point molecular vibrations of the atom. The influence of this new value of $T_e$ on the Doppler broadening of the nuclear level and hence on the resulting value of ${\Gamma }_0$ as deduced from a self-absorption measurement is discussed.

It is shown that the method of Hernández and Mondragón for generating the Gamow states of a local or nonlocal potential in momentum representation is equivalent to a method based on an expansion of the potential in separable kernels and Berggren’s rules of handling Gamow states. The advantage of this way of producing Gamow states over the direct numerical integration of the Schrödinger equation in coordinate representation is pointed out and the feasibility in practical problems is demonstrated.

The absolute electrofission cross section of ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ was measured in the energy range 40–250 MeV. The data analysis, based on the virtual-photon technique, showed that the excitation mechanism which can cause the fission of ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ is the Levinger’s modified quasi-deuteron, even at energies well above the pion threshold.

We calculate bremsstrahlung spectra for intermediate energy heavy ion collisions to see the sensitivity of photon cross sections to reaction dynamics. Modeling the collisions with the intranuclear cascade, we find a clear collective quadrupole bremsstrahlung signal only for heavier nuclei, A>40. Maximum sensitivity to dynamics is likely for photons in the range of 10–30 MeV. For higher energy photons or lighter nuclei, there is a large background coming from the incoherent dipole component of the bremsstrahlung.