We present a simple prescription for the determination of the nuclear softness parameter, a measure of low-spin variation of the moment of inertia, in the interacting boson model. The formulation makes use of explicit dependence of the moment of inertia on the d-boson mixing parameter. The systematics of the softness parameter are carried out using an effective interacting boson model Hamiltonian approach and results are found to be in excellent agreement.

Level densities for hot isobaric nuclei are investigated by incorporating the isospin fluctuations in the statistical theory of nuclei. The single-particle level density parameter a is extracted as a function of temperature for various isospins of the system. At large temperatures, the empirical value of a≃A/8 is reproduced. A new method of extracting the neutron-proton asymmetry parameter is proposed. The neutron-proton asymmetry parameter is found to depend very strongly on deformation and isospin at low temperatures. The effect of the shell structure on the asymmetry energy is predominant for certain isospins corresponding to stable neutron-proton combinations. Results are presented for A=42, 44, 46, and 208. The excitation energy versus isospin plot for constant entropy of the system exhibits pockets similar to yrast traps in high-spin states of highly excited nuclei.

In an investigation of A=153 isotopes fine structure was observed in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$ α decay. Besides the previously known α transitions that feed the ${}_{}{}^{149}{}_{}{}^{}\mathrm{Ho}$ $h_{11/2}$ (0.0 keV) and $s_{1/2}$ (49.0 keV) isomers, two, very much weaker, α groups were found to populate the $d_{3/2}$ (220.4 keV) and $d_{5/2}$ (564.4 keV) states in ${}_{}{}^{149}{}_{}{}^{}\mathrm{Ho}$. Based on the ${}_{}{}^{149}{}_{}{}^{}\mathrm{Ho}$ level scheme and on the $Q_{\alpha }$ values for the two main ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$ α transitions, we determine that the $h_{11/2}$ level in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$ is the ground state and that the $s_{1/2}$ state lies 43±7 keV above it. Energy systematics for the $s_{1/2}$ and $h_{11/2}$ proton states in even-N odd-Z nuclei near N=82 are discussed.

The energy of the 1022 keV gamma ray which follows the positron decay of ${}_{}{}^{10}{}_{}{}^{}\mathrm{C}$ has been measured to be 1021.646±0.014 keV. This is a necessary step in an accurate determination of the ft value of the pure Fermi component of the decay.

It is shown that the differential cross section for Compton scattering of 25–100 MeV photons on Pb through θ=30° is very sensitive to the polarizability of the bound nucleon. A first experiment led to ${1.2}_{\mathrm{-}0.3}^{+0.4\mathrm{}}$ times the free-nucleon value.

The average multiplicities ν¯(A) of prompt neutrons emitted in the spontaneous fission of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ and ${}_{}{}^{258}{}_{}{}^{}\mathrm{Fm}$ are derived. Two new features are predicted: A simple sawtooth for ${}_{}{}^{258}{}_{}{}^{}\mathrm{Fm}$ and a triple one for ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$. Experiments to check these predictions should be feasible now.

The isospin relaxation is studied at high incident velocity for short interaction times where large collective amplitudes can play an important role. For the ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$${+}^{98}$Mo collision at 1440 MeV incident energy, the triple differential cross section ${\mathit{d}}^3$σ/dA dZ ${\mathit{dE}}_{\mathrm{loss}}$ of the reaction products has been measured. The symmetric ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ system was found to offer the best possibilities to obtain in a unique way the primary distributions in the (A,Z) plane, using a ${\chi }^2$ method. Corrections due to particle evaporation and experimental resolution are taken into account. The predictions of the statistical model and of a collective model with quantum treatment of the charge asymmetry degree of freedom are compared with the primary isobaric variances.

Isovector $E_C^{\mathrm{}\left(1\right)\mathrm{}}$ and isotensor $E_C^{\mathrm{}\left(2\right)\mathrm{}}$ parts of the nuclear Coulomb energy for 61≤A≤209 have been extracted from energies of corresponding states using the isobaric mass equation. These $E_C^{\mathrm{}\left(1\right)\mathrm{}}$ and $E_C^{\mathrm{}\left(2\right)\mathrm{}}$ continue to show the same overall variation, linear in $A^{2/3}$ and approximately $A^{\mathrm{-}1/3}$, respectively, as do the values for A≤60.

We estimate the admixture of six-quark state in the deuteron from its magnetic moment by using a simple hybrid model. The six-quark probability comes out to be between 3–6 % and is dependent upon the nucleon-nucleon interaction.

A narrow, strongly excited state was observed in the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}(\alpha ,p){}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ reaction at 23.288 MeV. This excitation energy is in agreement with peaks seen in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(p,{\pi }^{+}){}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}(e,e^{\prime }){}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ reactions. However, the ($p,{\pi }^{+}$) work indicates that this state may be a $3^{-}$, $T=2\mathrm{}$ state. The population of this level via the ($\alpha ,p$) reaction rules this out. Furthermore, weak coupling calculations suggest that the centroid of the $\left|{}_{}{}^{11}{}_{}{}^{}\mathrm{B}\otimes \nu \right(p_{\frac{1}{2}},d_{\frac{5}{2}}),\pi (d_{\frac{5}{2}})〉$ configuration lies very close to this energy. It is therefore more probable that this state has a spin and parity of $7^{+}$, $T=1\mathrm{}$ rather than a $3^{-}$, $T=2\mathrm{}$ assignment.

Light fragments (H, ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$) were detected in coincidence with high-energy ($E_{\gamma }>20\mathrm{}$ MeV) gamma rays from collisions of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ on Zn at a beam energy of $\frac{E}{A}=40\mathrm{}$ MeV. The light fragment coincidence energy spectra and angular distributions were similar to those from inclusive measurements. The charged-particle fold distribution measured in coincidence with either gamma rays or with light fragments are nearly the same. These results suggest that high-energy gamma-ray production occurs over a broad range of impact parameters.

Employing diagrammatic techniques, a model for the reactions ${}_{}{}^1{}_{}{}^{}\mathrm{H}(\gamma ,K^{+})\Lambda$ and ${}_{}{}^1{}_{}{}^{}\mathrm{H}(e,e^{\prime }{K}^{+})\Lambda$ is derived with the coupling constants being determined phenomenologically by a least-squares fit to the available data. We find a strong sensitivity of the photoproduction process to $t$-channel exchange terms. The inclusion of the kaon resonance $Q1\left(1280\mathrm{} \mathrm{MeV}\right)$ brings the dominant $K\Lambda N$ coupling constant in agreement with predictions from the analysis of $\mathrm{Kp}$ scattering data. An excellent fit to the electroproduction data confirms former measurements of the kaon radius.

Elastic and inelastic $p+{}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ observables are calculated using a relativistic impulse approximation model for the diagonal optical potential and a simple collective ansatz for the transition potentials. The calculations were performed using Dirac coupled channel codes. Agreement with large angle elastic-scattering data is greatly improved by the inclusion of strongly coupled, lowlying collective states.

Th, U, and Ta targets were irradiated by positrons from ${}_{}{}^{118}{}_{}{}^{}\mathrm{T}\mathrm{e}-{}_{}{}^{118}{}_{}{}^{}\mathrm{S}\mathrm{b}-{}_{}{}^{118}{}_{}{}^{}\mathrm{S}\mathrm{n}- {\beta }^{+}$ sources. Electron spectra were taken by means of an electron spectrometer and a position-sensitive electron counter. We have observed an electron line located at 328.6 ± 0.4 keV in the spectra from Th and U targets, but not in the Ta target. The kinetic energy and the intrinsic full widths at half maximum of the line were deduced to be 330.8 ± 1.0 keV and 3.7 ± 0.5 keV, respectively. The cross section was estimated to be 28 ± 10 mb/sr and 34 ± 13 mb/sr for Th and U, respectively.

Using a beam of 72 MeV helions, wide-range angular distributions were recorded for the charge-exchange reaction ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}({}_{}{}^3{}_{}{}^{}\mathrm{He},t){}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ to the ground, analog, and Gamow-Teller states of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$. At far-side-dominated larger scattering angles, pronounced rainbowlike bumps are observed for the first time in charge-exchange channels, but shifted somewhat forwards compared with the elastic scattering. A distorted-wave Born approximation analysis shows substantial sensitivity to the charge-exchange form factors as well as to the choice of triton versus helion optical potentials.

Strong excitation of both (π$d_{5/2}$,ν$d_{5/2}^{\mathrm{-}1}$) $5^{+}$, 0 ħω and (π$f_{7/2}$,ν$d_{5/2}^{\mathrm{-}1}$) $6^{\mathrm{-}}$, 1 ħω stretched-state strength is observed in the ${}_{}{}^{26}{}_{}{}^{}(\mathit{p}$,n${)}^{26}$Al reaction at 134.4 MeV. The T=0, $5^{+}$ strength is observed to be predominantly in the ground state which has 56% of the strength predicted by a distorted-wave impulse approximation calculation that assumes the extreme single-particle-hole model. Another 17% of this strength is observed in a $5^{+}$ state at 3.4 MeV. The $6^{\mathrm{-}}$ strength is split into three isospin components: 61% of the extreme single-particle-hole model T=0, $6^{\mathrm{-}}$ strength is observed in three states between 6.9 and 11.0 MeV; 58% of the predicted T=1 strength is observed in nine states between 9.3 and 16.5 MeV; 27% of the predicted T=2 strength is observed in a single state at 18.2 MeV. The observed $6^{\mathrm{-}}$-state excitation energies are in general agreement with the T=0 and 1, $6^{\mathrm{-}}$ states observed in the ${}_{}{}^{25}{}_{}{}^{}(\mathit{\alpha }$,t${)}^{26}$Al reaction and with the analog T=1 and 2, $6^{\mathrm{-}}$ states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ observed in inelastic electron and proton scattering. The total observed $5^{+}$ strength and its distribution are in good agreement with distorted-wave impulse approximation calculations that use full S-D shell-model wave functions. The total $6^{\mathrm{-}}$ strength and its distribution are generally indicated by a shell-model calculation that assumes only 2p2h correlations in the ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ target nucleus and requires one particle in the 1$f_{7/2}$ orbital for the final $6^{\mathrm{-}}$ states; quantitatively, the calculation predicts less fragmentation than observed.

This paper provides a further test of employing the W-matrix representation of the two-body T matrix in three-nucleon calculations. Calculating differential neutron-deuteron breakup cross sections with the Malfliet-Tjon potentials I and III, we find that the single-term separable approximation for the two-body T matrix which follows from the W-matrix approach, when used as input in the three-nucleon Alt-Grassberger-Sandhas equations, leads to results which agree extremely well with benchmark results provided by Wital/a, Glöckle, and Cornelius. The present investigations, thus, corroborate and extend the findings obtained previously for elastic neutron-deuteron scattering. Our theoretical results are also compared with recent experimental data obtained at Erlangen, and it is found that the Malfliet-Tjon potential supports a very good reproduction of the overall features of these data. We conclude that the W-matrix approach provides a remarkably simple and efficient tool for high-quality three-nucleon calculations.

The cross section and transverse tensor analyzing power ${}_{}{}^{\mathrm{T}}{}_{}{}^{}\mathrm{T}_{20}^{}{}_{}{}^{}$ have been measured in kinematically complete geometry for the ${}_{}{}^4{}_{}{}^{}(\mathit{d}$,pα)n reaction at 7 MeV. Kinematic conditions were chosen to correspond to production of the singlet deuteron ($d^{\mathrm{*}}$) near a c.m. angle of 100°. The data show clear evidence for production of the $d^{\mathrm{*}}$. A comparison of the measured cross sections and analyzing powers with the results of three-body calculations shows good agreement in the kinematic region away from that in which the $d^{\mathrm{*}}$ is produced, but this agreement worsens as the region in which $E_{\mathrm{np}}$=0 is approached. In this region, the data are reproduced qualitatively by a calculation which includes the singlet n-p interaction as well as an improved approximation to the p-α Coulomb interaction, but the magnitude of the cross section is underpredicted in this calculation.

We investigate the applicability of the distorted wave impulse approximation on the factorization assumption for the (p,2p) reaction in the lower incident energy. We calculate contour maps of analyzing powers and cross sections for the ${}_{}{}^{12}{}_{}{}^{}$C(p→,2p) reaction at an incident energy $E_p$=84 MeV using distorted wave impulse approximation including the spin-orbit interaction for the distorted waves. The proton-proton t matrix elements are calculated with the effective nucleon-nucleon interaction by Love-Franey taking account of the off-shell effect. Our calculations agree well with both experimental analyzing power and cross section data on the whole region of the contour maps.

Proton stripping with the 55.2 MeV ${}_{}{}^{25}{}_{}{}^{}\mathrm{He}$,d${)}^{26}$Al reaction has been used to populate $6^{\mathrm{-}}$ states known from other reactions or by analogy to the states excited in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ by electron scattering. Spectroscopic factors are, in general, in good agreement with those obtained in a lower resolution study of the ${}_{}{}^{25}{}_{}{}^{}(\mathit{\alpha }$,t${)}^{26}$Al reaction, when similar reaction distorted-wave Born approximation calculations are made. More high-lying states are found in the ${(}^3$He,d) study than in the (α,t) work. The differences between scattering and single-proton stripping excitation of the simple stretched states are confirmed.