The (p→,n) reaction has been measured for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ targets at 290 MeV for a lab angle of 20.4° and at 420 MeV for a lab angle of 24.0°. An additional angle of 27.0° was measured for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at 290 MeV. Both cross sections and analyzing powers were obtained up to excitation energies close to the quasifree peak. The (p→,n) analyzing powers are suppressed relative to the free nucleon-nucleon values for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ data at 290 and 420 MeV, and for the ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ data at 290 MeV. An enhanced analyzing power is observed for the ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ data at 420 MeV. The data are compared with both relativistic and nonrelativistic model calculations.

Scaled factorial moments, corrected for the shape of the single-particle pseudorapidity distribution, are analyzed in pseudorapidity and in two-dimensional (pseudorapidity and azimuth angle) space. An intermittent, power-law growth of the moments with decreasing bin size is found, with two-dimensional analysis revealing a much stronger effect than for one-dimensional for nucleus-nucleus data. The intermittent patterns are more evident for proton-nucleus than for nucleus-nucleus collisions, with the heaviest nucleus, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$, showing the weakest effect.

The statistical γ-ray decay of the giant dipole resonance built on highly excited states in ${}_{}{}^{151\mathrm{-}156}{}_{}{}^{}\mathrm{Dy}$ has been used as a probe for studying the evolution of the nuclear shape with increasing angular momentum. The observed shift of the giant dipole resonance strength to lower energy suggests a change of the nuclear deformation from prolate to oblate with increasing spin.

Inelastic electron scattering cross sections for ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ have been measured at a scattering angle of 180°, with incident beam energies ranging from 81.9 to 268.9 MeV. Transverse form factors were measured for transitions to low-lying natural-parity states, to unnatural-parity ‘‘stretched’’ $J^{\pi }$${=4\mathrm{}}^{\mathrm{-}}$ states, and to the $J^{\pi }$${=2\mathrm{}}^{\mathrm{-}}$ analog to the ${}_{}{}^{14}{}_{}{}^{}\mathrm{B}$ ground state. Cross sections for $4^{\mathrm{-}}$ states at 11.7 and 17.3 MeV are combined with pion scattering data to determine the isoscalar and isovector transition amplitudes. Form factors for other states are compared to shell-model calculations. From the excitation energy of the newly discovered $J^{\pi }$T${=2\mathrm{}}^{\mathrm{-}}$2 state at 22.1 MeV, the ${}_{}{}^{14}{}_{}{}^{}\mathrm{-}_{}^{14}{}_{}{}^{}$B Coulomb energy difference is determined to be 2.25±0.10 MeV.

Angular distributions of the double differential cross section $d^2$σ/dΩ dE(σ) and the spin-flip probability $S_{\mathrm{nn}}$ have been measured for inclusive proton inelastic scattering from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at 319 MeV. Excitation energies (ω) up to about 40 MeV have been investigated over the angular range from 3.5° to 12° in the laboratory (0.3 to 0.9 ${\mathrm{fm}}^{\mathrm{-}1}$). Here, multipole decompositions of angular distributions of σ$S_{\mathrm{nn}}$ for the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(p→,p→ ’) reaction at 319 MeV have been performed in order to compare ΔS=1 strength observed with sum rules. In contrast to the well-known quenching of Gamow-Teller and M1 resonances, the spin-dipole resonance has a total measured strength which is larger than that predicted by the energy-weighted sum rule. The spin-dipole strength distribution supports asymmetric widths predicted by calculations including 2p-2h mixing. The spin-quadrupole resonance is observed near ω=35 MeV and its total strength for ω<40 MeV estimated.

We have measured the γ-ray branching ratio ${\Gamma }_{\gamma }$/Γ of the unbound 5.17 MeV first excited state in ${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$ using the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^3$He,nγ) reaction at ${\mathit{E}}_{3_{\mathrm{He}}}$=9.35 MeV. We detected coincidences between $n_1$ neutrons populating the ${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$ state and 5.17 MeV γ rays from its decay, and obtained ${\Gamma }_{\gamma }$/Γ=(7.2±3.5)×${10}^{\mathrm{-}5}$. When combined with the known total width Γ=38.1±1.8 keV, our branching ratio corresponds to ${\Gamma }_{\gamma }$=2.7±1.3 eV. We use this γ-ray width, together with previously measured nonresonant ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(p,${\gamma }_1$) data, to find the ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$(p,γ) reaction rate at astrophysical energies, thereby determining the stellar environments where hydrogen burning through ‘‘hot’’ or β-limited CNO cycle can occur.

Quark basis states constructed from molecular-type orbitals were shown previously to be more convenient to use than cluster model states for N-N processes. The usual cluster model representation omits configurations which emerge naturally in a molecular basis which contains the same number of spatial functions. The importance of the omitted states was demonstrated for a constituent quark model. The present work extends the study to the prototypical current quark model, namely the MIT bag. In order to test the expansion for short-range N-N interactions, the eigenstates and eigenenergies of six quarks in a spherical bag, including one-gluon exchange, are calculated. The lowest eigenenergies are lowered significantly with respect to the usual cluster model. This reaffirms the importance of dynamics for obtaining the needed short-range repulsion.

The deuteron photodisintegration in the Δ-resonance region is calculated within a unitary theory of the NN-NΔ-πNN system coupled to the photon. The photoexcitation amplitude of the Δ is deduced from the $M_{1+}$((3/2) pion photoproduction amplitude consistently with its background term and the πN interaction. The NN-NΔ transition amplitude is obtained from the coupled equations for the NN-NΔ-πNN system. The one-pion-exchange currents as well as the normal single-nucleon current are included. The polarization parameters are reproduced quantitatively, but the cross section is slightly underestimated. Comparison of our results with those of the NN-NΔ coupled-channel model is made. Effects of relativistic corrections and gauge-invariance constraints are discussed.

We derive a momentum-space formulation of the deuteron photodisintegration in terms of nonsingular scattering integral equations. The two-body T matrix describing the nuclear final-state interactions enters only on shell, thus offering the possibility of determining it entirely in terms of experimental phase shifts. The formalism suggests a lowest-order approximation which goes beyond the usual plane-wave approximation and which contains the full information of the on-shell final-state interaction. Test calculations using the Reid soft-core potential are reported. It is found that the numerical solution of photodisintegration observables is greatly facilitated by the proposed formalism. Moreover, the lowest-order approximation is seen to be superior to the usual plane-wave approximation, providing good results even in those cases where the usual plane-wave approximation vanishes. Extensions to more complex few-nucleon systems are discussed.

The $7^{+}$ states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ were studied by the ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$(α,d${)}^{26}$Al reaction at $E_{\alpha }$=63.7 MeV and by the ${}_{}{}^{25}{}_{}{}^{}\mathrm{Mg}$${(}^3$He,d${)}^{26}$Al reaction at $E_h$=55.2 MeV. Five $7^{+}$ states were newly identified, in addition to the known 8.14-MeV $7^{+}$ state, from the (α,d) angular distributions. Comparisons of the (α,d) and ${(}^3$He,d) cross sections showed that the 11.81-MeV state was excited through the ($d_{5/2}$$g_{9/2}$) component and the other $7^{+}$ states through the ($f_{7/2}$${)}^2$ component.

Coincident protons from the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,p’p’’) at an incident proton energy of 200 MeV have been measured. Continuum cross sections were extracted from the experimental data corresponding to the detection of protons at primary angles of -20° and -45° with energies of 70±5, 100±5, and 130±5 MeV for secondary angles between 20° and 145°. Comparisons were made with a model which describes the reaction mechanism as originating from an initial quasifree nucleon-nucleon interaction between the incident proton and a single target nucleon, followed by the rescattering of the struck nucleon, which behaves as an intranuclear projectile, from the spectator part of the target nucleus. Reasonable agreement has been found between the calculated and measured cross sections.

The validity of the distorted-wave impulse approximation treatment has been investigated for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,2p${)}^{11}$B knockout at an incident energy of 200 MeV for coplanar geometries which are very different from those at which quasifree knockout is usually studied. Good agreement in shape has been found between the calculated and measured energy-sharing distributions over a wide range of kinematic conditions. Except at very forward symmetric angles, the distorted-wave impulse approximation treatment was found to be insensitive to the choice of the initial- or final-energy prescriptions for the two-body scattering approximation. An average spectroscopic factor of 1.1±0.3 was extracted.

The ${}_{}{}^{33}{}_{}{}^{}\mathrm{S}$(p,$p_0$), (p,$p_1$), and (p,$p_2$) differential cross sections were measured in the energy range $E_p$=1.20–3.77 MeV with an average overall energy resolution of 350 eV full width at half maximum. Resonance parameters were extracted for 144 levels with a multilevel, multichannel R-matrix code; parameters include resonance energy, total angular momentum, proton partial widths, and channel spin and orbital angular momentum mixing ratios. The l=1 strength function is more than an order of magnitude larger than the l=0 strength function. Most of the l=1 strength is below $E_p$≊2.6 MeV and most of the l=0 strength is above $E_p$≊2.4 MeV.

The proton stripping reaction ${}_{}{}^{17}{}_{}{}^{}\mathrm{He}$,d${)}^{18}$F has been used to reinvestigate the proton widths of the states in ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ near the proton threshold. Distorted-wave angular distributions were calculated using appropriate methods for stripping to unbound states. The deduced proton width for the level at $E_x$=5.673 MeV ($J^{\pi }$${=1\mathrm{}}^{\mathrm{-}}$) is significantly larger than a previous value obtained from a direct radiative capture experiment. A subthreshold state at $E_x$=5.603 MeV ($J^{\pi }$${=1\mathrm{}}^{+}$) was found to have a rather large proton reduced width so that this state contributes significantly to the astrophysical S factor at low energy. These measurements lead to substantial changes in the stellar reaction rate for the ${}_{}{}^{17}{}_{}{}^{}(\mathit{p}$,α${)}^{14}$N reaction. This result is discussed in relation to recent observation of the isotopic abundance ratio ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${/}^{17}$O in red giant stars. In addition, the nuclear structure of ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ is studied via the measurement of spectroscopic factors for most of the levels in ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ bound against proton decay.

The excitation-energy distribution of transition strength to $1^{+}$ states was measured for the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$(p,n${)}^{208}$Bi reaction at 134.3 MeV for excitation energies up to 38 MeV. Structures observed in neutron time-of-flight spectra with forward-peaked (ΔL=0) angular distributions were identified as $1^{+}$ states, except for the transition to the $0^{+}$ isobaric analog state. The $1^{+}$ strength in these structures was extracted by normalizing the yield above a fitted polynomial background to the Fermi transition strength localized in the isobaric analog state. The Gamow-Teller strength observed in the $1^{+}$ peaks is 56% of the 3(N-Z) sum rule when the strength of the ${\beta }^{+}$ transitions is assumed to be zero; 45% of 3(N-Z) is observed in the giant resonance and 10% is observed in structures below the giant resonance. Based on a multipole decomposition analysis, an upper limit on the $1^{+}$ strength in the apparent continuum to 38 MeV of excitation energy is estimated to be 37% of 3(N-Z). These results are compared with predictions from a shell model that includes a pairing force and a long-range Gamow-Teller force in both the parent and daughter nuclei.

Cross sections were measured radiochemically for the ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$(n,p${)}^{92}$${\mathrm{Nb}}^{\mathrm{m}}$ and ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$(n,n’p +pn+d${)}^{91}$${\mathrm{Nb}}^{\mathrm{m}}$ reactions over the neutron energy range of 9.0–10.6 MeV, and for the latter reaction also between 12.6 and 14.4 MeV. Use was made of high-resolution γ-ray and x-ray spectroscopy. Statistical-model calculations taking into account precompound effects were performed for fast neutron induced reactions on ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$. The calculational results agree well with the experimental data on emitted proton spectra as well as on the excitation functions of various reaction channels. The second-chance proton emission is significant for incident neutron energies above 11 MeV; between 13 and 14 MeV it is comparable to the first-chance proton emission.

Coupled-channel calculations using uniform optical parameters are compared for rotational and harmonic vibrator sequences of states, truncating all states of the sequence above a certain nuclear energy level. It is found that the inelastic cross section for the highest included state is somewhat larger than a coupled-channel calculation which includes the next state of the sequence. This effect is due to the absence of the absorption taking place through the truncated state. Except at very low bombarding energies, the cross sections for lower states in the sequence are virtually unaffected by the truncation. Approximate formulas are presented and tested for correcting the optical potential of the highest included state. Good agreement is obtained with coupled-channel calculations that include these higher states explicitly. Application is made to the problem of obtaining inelastic deformation parameters β with distorted-wave Born approximation and with different coupling schemes.

Charged-particle-γ and charged-particle-neutron-γ coincidences have been used to identify in-beam γ-ray transitions in ${}_{}{}^{69}{}_{}{}^{}\mathrm{Se}$ produced in the reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^{32}$S,2pn${)}^{69}$Se. Charged-particle-γ-γ coincidences, neutron-γ-γ coincidences, and neutron-gated γ-ray angular distributions were used to deduce the level scheme. A long-lived isomer attributed to the $g_{9/2}$ state was found; its half-life was measured with charged-particle-γ timing as 1023±110 ns. The presence of strong ΔJ=1 and ΔJ=2 transitions in the band built on the ν$g_{9/2}$ neutron single-particle state and the measured sign of the E2/M1 mixing ratio for the ${(11/2\mathrm{}}^{+}$→${(9/2\mathrm{}}^{+}$ transition are consistent with a theoretically predicted oblate shape for this nucleus.

The canonical formulation of equilibrium statistical multifragmentation is examined. It is shown that the explicit construction of observables (average values) by sampling the partition probabilities is unnecessary insofar as closed expressions in the form of recursion relations can be obtained quite easily. Such expressions may conversely be used to verify the sampling algorithms.

High angular momentum states in ${}_{}{}^{144}{}_{}{}^{}\mathrm{Nd}$ are studied via the γ rays produced in the ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$${(}^{18}$O, 4n${)}^{144}$Nd reaction. In addition to the previously known sequence of states built on the $3_1^{\mathrm{-}}$ state, we have observed another negative-parity sequence built on the 3395 keV $9^{\mathrm{-}}$ state, which is apparently of a two quasiparticle nature. These two negative-parity sequences probably interact and mix significantly. The present ${}_{}{}^{144}{}_{}{}^{}\mathrm{Nd}$ results raise questions regarding the interpretation of medium spin states of ${}_{}{}^{146}{}_{}{}^{}\mathrm{Nd}$ in terms of strong octupole correlations.