The properties of several hybrid mass relations are examined through the study of (i) statistical tests, (ii) systematic effects, and (iii) the structure of the solutions of partial difference equations. The usefulness of the relations is discussed. Mass relations based on the effective neutron-proton interaction and on derivatives thereof have particularly small relation inaccuracies.

Special distribution methods have been used to make nuclear level-density calculations with full inclusion of two-body forces. The demands on computer time are large, however, and the information obtained in the very lowest energy region is not as extensive as would be desirable. We present calculations of the level density of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ obtained with an alternative, but closely related, procedure based on the Lanczos algorithm. In addition, we discuss the possibility of accelerating the calculation of the moments for conventional spectral distribution calculations. Very encouraging results for both the Lanczos technique and the revised moment algorithm are obtained; some remaining problems are examined.

Boson-fermion symmetries and supersymmetries associated with the U(5)×SU(2) limits in the interacting boson fermion model with j=(3/2), (5/2) and j=(1/2), (3/2), (5/2) are developed in detail. Their relevance for the description of the available experimental data on the low-energy spectra of the nuclei ${}_{}{}^{76}{}_{}{}^{}\mathrm{Se}$ and ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ is examined.

Gamma-ray transitions in ${}_{}{}^{205}{}_{}{}^{}\mathrm{Hg}$ have been observed in the ${}_{}{}^{204}{}_{}{}^{}\mathrm{Hg}$(t,d${)}^{205}$Hg reaction. A partial level scheme is obtained. Delayed gamma rays exhibiting ${\tau }_m$=(1.59±0.06)×${10}^{\mathrm{-}3}$ s are observed; the identification with the decay of the $i_{13/2}$ neutron hole state is suggested.

Measurements were made of the 90° cross sections of the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$(d,${\gamma }_0$${)\mathrm{}}^{13}$C reaction in the energy region of the previously reported secondary doorway state in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$. Angular distribution data of the cross section, vector analyzing power, and tensor analyzing power $T_{20}$(0) were measured over the same energy region. The current data were combined with the neutron capture data of the previous study, and both data sets were analyzed simultaneously using a secondary doorway state formalism.

We give a modified separable representation of the Paris potential, which is to remedy shortcomings of an earlier parametrization in the ${}_{}{}^1{}_{}{}^{}\mathrm{S}_0^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{P}_0^{}{}_{}{}^{}$ partial waves. In particular, the present parametrization does not lead to the unphysical bound states at very large negative energies as encountered previously. Still, it provides for a good approximation of the on-shell as well as off-shell properties of the Paris potential.

The effects on the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${+}^{64}$Ni fusion cross section due to the coupling of the entrance channel to inelastic and transfer channels with positive Q value are calculated, making use of macroscopic form factors for both processes. It is found that the effective lowering of the barrier amounts to ∼8 MeV, consistent with recent experimental data. About 35% of this magnitude results from the positive Q-value transfer couplings.

The effects of adding the d${+\mathrm{}}^5$He cluster configuration to a formulation consisting of ${}_{}{}^3{}_{}{}^{}$H+α, n${+\mathrm{}}^6$Li, and n${+\mathrm{}}^6$${\mathrm{Li}}^{\mathrm{*}}$ cluster configurations are examined. The result shows that, because of the reduction effect of the Pauli principle, the improvement in the ${}_{}{}^3{}_{}{}^{}$H+α ground-state cluster separation energy and scattering phase shift is only moderate. On the other hand, the calculation also indicates that the deuteron spectroscopic factor in the ground state of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ is likely to have an appreciable magnitude, in agreement with experimental finding.

It is demonstrated that the interacting-boson model, which does not distinguish between neutron and proton bosons, does not reproduce well-known E4 systematics for deformed rare-earth nuclei and adjacent transitional nuclei. It is concluded that this probably indicates the need for g bosons, even in very low-lying states.

Isotopic differences in the fusion cross sections for 0+0, observed by Thomas, et al., are interpreted with a coupled-channel model. We find that most of the subbarrier enhancement of ${}_{}{}^{18}{}_{}{}^{}$O${+\mathrm{}}^{16}$O over ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{16}$O is attributable to the excitation of the low $2^{+}$ state in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$. However, the model predicts the enhancement to persist above the barrier, contrary to experimental findings.

An approach we have proposed recently for calculating fusion cross sections ${\sigma }_F$ is applied to the analysis of fusion data for the ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{40}$Ca system, for $E_{\mathrm{lab}=40\mathrm{}–}$215 MeV, which covers the so-called regions I and II. It is shown that the ${\sigma }_F$ data in this wide range of $E_{\mathrm{lab}}$ were fitted rather nicely with our approach, thanks to the fact that energy-dependent optical-model parameters were available.

Results of detailed calculations which reproduce the sawtooth dependence of neutron multiplicity on fragment mass in nuclear fission are presented. The same sawtooth seems to occur in deep-inelastic heavy-ion reactions when target and projectile are sufficiently unequal. These results support an idea by Whetstone and suggest a method for the inclusion of shell effects which is different from that employed in the scission-point models.

Using the classical limit of the neutron-proton interacting boson model, a simple expression is derived for the excitation energy of the collective M1 mode. It is shown that in the SU(3) and SO(6) limits this result is identical to the exact value. For ${}_{}{}^{156}{}_{}{}^{}\mathrm{Gd}$ it agrees to within 2% of the exact value, to be compared with a 12% discrepancy reported by Balantekin and Barrett.

Several experiments suggest that the phase transition model is not applicable to the wide range product masses and projectile energies that were considered in a recent analysis of light fragment formation. Detailed conclusions concerning critical temperatures and exponents probably reflect changes in mechanism as well as problems with the treatment of the experimental data in that analysis.

The first observation of the reaction dd→αη is reported. The missing mass spectrum in dd→αX shows an enhancement at the α momentum corresponding to the η mass. The corresponding c.m. cross section is 0.25±0.10 nb/sr for η’s produced at 146° in the c.m.

The population of bound (γ-decaying) states of the projectilelike fragments from the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$${+}^{164}$Dy reaction at 20 MeV/nucleon was studied by measuring coincidences between these fragments and γ rays detected with large volume bismuth germanate detectors. The results indicate that products of pickup and exchange reactions are more likely to be excited than products of stripping reactions, particularly in fast, peripheral collisions.

From the measurements of laboratory system emission angles θ of 2188α and 298 Li fragments, produced inclusively by relativistic Fe-C Fe-Pb collisions, a target-independent differential frequency formula, dN=exp(a+b cotθ)d(cotθ) is obtained with the constant b≃-0.026 at 1.88 GeV/nucleon, which seems also to be independent on the kinds of projectile fragments. The significance of this approximate formula is discussed in relation mainly with Kaplon’s formula.

We propose that the giant resonances in nuclei are associated with a R(4) symmetry and therefore exhibit a hydrogen-like structure. The agreement between the theory and the experimental data is quite satisfactory for both charge conserving and charge exchange resonances with and without spin flip.

The decay of radiochemically separated ${}_{}{}^{144}{}_{}{}^{}\mathrm{Ce}$ source in equilibrium with ${}_{}{}^{144}{}_{}{}^{}\mathrm{Pr}$ isomers has been reinvestigated with HPGe detectors. The energies and intensities of 19 γ rays were measured, of which three are new. A ${}_{}{}^{144}{}_{}{}^{}\mathrm{Nd}$ level scheme allows the incorporation of most of the transitions between 13 excited states. Levels at 2072.8 ($2^{+}$), 2368.3 ($2^{+}$), 2581.8 ($3^{+}$), and 2742.8 ($0^{+}$) keV, observed earlier in nuclear reactions, are found to be fed in these decays. A 2675.3 keV ($J^{\pi }$${=0\mathrm{}}^{+}$) level seems to be a component of the 2.663 MeV multiplet observed in the (p,t) reaction.