The method of correlated basis functions is generalized to describe three-nucleon and deuteron-plus-nucleon continuum states. The correlated basis functions are obtained by incorporating short range correlations between the spectator nucleon and the two nucleons of the interacting pair. Correlated orthonormal wave functions for the continuum states are generated by orthogonalizing the correlated basis functions via a combination of Schmidt and Löwdin transformations, designed so that the correlated orthonormal states have correct energies. The correlated orthonormal continuum states include the minimum interaction effects required to ensure orthogonality and reasonable short range behavior. The longitudinal response of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ at k=300 to 600 MeV/c is calculated with the variational ground state wave function and the correlated orthonormal final states. Both the short range correlations and the orthogonality corrections in the final states decrease the response in the quasi-free peak. The calculated response has the correct sum and energy-weighted sum within ∼5%, and that of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is in reasonable agreement with the Saclay experimental data. We find that the response of ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ is broader than that of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and that it is relatively larger at energies greater than that of the quasi-free peak.

Radiative capture of protons leading to the first excited state of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ($E_x$=6.05 MeV, $J^{\pi }$${=0\mathrm{}}^{+}$) has been measured in the energy range $E_{\mathrm{p}=10\mathrm{}–}$17 MeV in 200 keV steps. A pronounced concentration of dipole strength is observed, which is interpreted as a giant dipole resonance built on the $0_2^{+}$ state. The observed strength has a γ-ray energy significantly less than that for the giant dipole resonance built on the ground state. The sign and magnitude of the shift is what would be expected if the giant dipole resonance observed is the lower energy component of a resonance split because of interaction with the quadrupole deformation of the $0_2^{+}$ state, although this conclusion is model dependent. The strength of the excited state giant dipole resonance is somewhat larger than would be predicted by simple models in which the strength scales with the proton spectroscopic factor of the final state.

The technique of spin exchange between laser optically pumped alkali-metal vapor and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ can provide several atm ${\mathrm{cm}}^{\mathrm{-}3}$ (≊${10}^{21}$ atoms in a volume of 6 ${\mathrm{cm}}^3$) of nearly 100% polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. We have recently produced 40% polarization of ${10}^{20}$ atoms of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ (3 atm in 1.3 ${\mathrm{cm}}^3$). It should therefore be possible to produce useful polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ targets by this technique. The realization of a practical target is limited by the contribution to depolarization by ionization during bombardment. This has been studied with a 360-nA, 18-MeV α-particle beam with encouraging results. A ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ target with 50–90 % polarization and a thickness of ${10}^{20}$ atoms ${\mathrm{cm}}^{\mathrm{-}2}$ is feasible. This paper presents the principles of the technique, the recent progress on spin exchange with optically pumped alkali-metal vapor, and studies of ionization-induced depolarization.

The real part of the central neutron${\mathrm{-}}^{208}$Pb mean field is the sum of a Hartree-Fock component plus a dispersive component. In keeping with theoretical expectations, the Hartree-Fock field is assumed to have a Woods-Saxon shape whose depth decreases exponentially with increasing energy and whose radius and diffuseness are independent of energy. The dispersive component is determined from the imaginary part of the optical-model potential by making use of the dispersion relation which connects these two quantities. The imaginary part is written as the sum of a volume and a surface-peaked contribution. The dispersion relation then implies that the real dispersive contribution is also the sum of volume and surface-peaked components. The parameters of the complex mean field are determined by fitting the available differential and polarization cross sections in the energy domain [4, 40 MeV] and the total cross sections in the domain [1,120 MeV]; these data are contained in previous published or unpublished reports, but new measurements of the total cross sections are presented from 1 to 25 MeV. Good fits to these cross sections, and also to unpublished total cross sections for energies up to 165 MeV, are obtained despite the fact that the number of adjusted parameters is quite small because of our use of the constraint implied by the dispersion relation.

The real part of the mean field is well approximated by a Woods-Saxon shape whose radius decreases with increasing energy between 5 and 25 MeV; its depth is approximately constant from 5 to 15 MeV and then decreases with increasing energy; these findings are in keeping with recent empirical evidence. When the neutron energy decreases below 2.5 MeV, the potential radius decreases; it increases again when the neutron energy decreases below -14.5 MeV. In the domain -20 MeV<E<0 the deduced potential accurately reproduces the experimental single-particle energies as well as the asymptotic values of the single-particle wave functions as measured from sub-Coulomb pickup reactions; it also yields excellent agreement with the spreading width of the deeply bound 1$h_{11/2}$ hole state. The rms radii, absolute spectroscopic factors, and occupation numbers are calculated for the valence particle and hole states. At the Fermi energy (-6 MeV), the mean field can be identified with the Hartree-Fock potential, for which the present analysis yields a depth of 46.4 MeV, a radius of 1.24$A^{1/3}$ fm, and a diffuseness of 0.68 fm. In the energy domain 4≤E≤10 MeV, the already good agreement between the predicted and measured cross sections is further improved if the imaginary part of the mean field is allowed to have its strength depend upon the neutron orbital angular momentum, and its surface diffuseness is allowed to be energy dependent.

High spin states in the two nuclei ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$ and ${}_{}{}^{52}{}_{}{}^{}\mathrm{Mn}$, with $J^{\pi }$≤${11}^{+}$, have been studied via the reactions ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$(α,p2nγ) and ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$(α,3nγ), respectively, by in-beam γ-ray spectroscopy. Measurements of lifetimes of excited states by the Doppler shift attenuation and recoil distance techniques, γ-ray angular distributions, excitation functions, and γγ coincidence, have been carried out in both the nuclei. New results obtained in ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$ are the mean lifetime values of ${0.35}_{\mathrm{-}0.13}^{+0.25\mathrm{}}$, ${0.23}_{\mathrm{-}0.11}^{+0.22\mathrm{}}$, and <2.0 ps for the three highest observed states 8216.0 (${11}^{+}$), 7237.1 (${10}^{+}$), and 6453.4 keV ($9^{+}$), and multipole mixing ratios ${\mathrm{-}0.10}_{\mathrm{-}0.05}^{+0.08\mathrm{}}$, ${0.06}_{\mathrm{-}0.03}^{+0.05\mathrm{}}$, and ${\mathrm{-}0.22}_{\mathrm{-}0.15}^{+0.08\mathrm{}}$ for the 978.9, 784.7, and 629.1 keV γ rays depopulating these states, respectively. In ${}_{}{}^{52}{}_{}{}^{}\mathrm{Mn}$, the lifetime of the 4163.4 keV (${10}^{+}$) state, hitherto unreported, has been measured to be ${0.20}_{\mathrm{-}0.16}^{+0.35\mathrm{}}$ ps.

Lifetimes of two other states in ${}_{}{}^{52}{}_{}{}^{}\mathrm{Mn}$, at 870.1 ($7^{+}$) and 2907.9 keV ($9^{+}$), for which only the upper limits were known previously, have been measured in this work and are found to be ${0.07}_{\mathrm{-}0.04}^{+0.08\mathrm{}}$ and 0.12±0.08 ps, respectively. A comparison of the present experimental results on level lifetimes, multipole mixing ratios, and transition probabilities with the available theoretical calculations shows that most of the levels in ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$ with excitation energies greater than 3.4 MeV are almost pure 1p5h states, while the lower lying states have a predominantly 0p4h configuration, with ∼20% 1p5h admixture. The observed M1 and E2 transition strengths between the high spin states in ${}_{}{}^{52}{}_{}{}^{}\mathrm{Mn}$ favor interpretation of these states as having predominantly ($f_{7/2}$${)}^n$ configuration and provide evidence for the existence of collective features in this nucleus.

We present a level spectrum for ${}_{}{}^{219}{}_{}{}^{}\mathrm{Ra}$ derived from data on the reaction ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$${(}^{14}$C,3n) studied at beam energies near the Coulomb barrier. Measurements of γ-ray excitation functions, γ-γ coincidences, γ-ray angular distributions, and electron conversion coefficients were made. The ground state band shows an alternating parity structure and is consistent with an interpretation in terms of a $g_{9/2}$ neutron weakly coupled to an even-even core. A nonyrast side band is observed and may arise from the anomalous coupling of a $j_{15/2}$ neutron to the core. The dependence of particle-core coupling behavior on the quadrupole deformation of the core and on the orbital in which the odd nucleon is located is discussed.

Two-particle correlations at small relative momenta were measured for ${}_{}{}^{16}{}_{}{}^{}\mathrm{induced}$ reactions on ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ at E/A=94 MeV, providing information about the space-time localization and excitation energy density of the emitting system. Two-particle correlation functions suggest that emission occurs from a region which is slightly larger than observed for ${}_{}{}^{14}{}_{}{}^{}\mathrm{induced}$ reactions at E/A=35 MeV, but significantly smaller than for ${}_{}{}^{40}{}_{}{}^{}\mathrm{induced}$ reactions at E/A=60 MeV. In contrast, the relative populations of widely separated particle unbound states are found to be surprisingly independent of incident energy and projectile mass.

Rotational bands in the odd-odd nucleus ${}_{}{}^{180}{}_{}{}^{}\mathrm{Re}$ have been studied via the ${}_{}{}^{176}{}_{}{}^{}\mathrm{Yb}$${(}^{10}$B,6n) and ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$(α,5n) fusion-evaporation reactions. A completely new high-spin level scheme has been obtained comprising four ΔI=1 bands and a ΔI=2 band. The ΔI=1 structures can be understood from quasiparticle states in neighboring odd nuclei and the ΔI=2 band is interpreted as a new example of a double decoupled sequence based on the decoupled $h_{9/2}$ proton and a ${(1/2\mathrm{}}^{\mathrm{-}}$[521] neutron. The different coupling schemes in a deformed doubly odd nucleus are discussed.

Several rotational bands built on one- and three-quasiparticle configurations have been populated in the odd-neutron ${}_{}{}^{133}{}_{}{}^{}\mathrm{Ce}$ nucleus following the ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$${(}^{18}$O,4n) reaction. Both signature components of bands built on the [514]${(9/2\mathrm{}}^{\mathrm{-}}$ and [400]${(1/2\mathrm{}}^{+}$ orbitals were observed. At low spins, the yrast band, based on a neutron from the upper $h_{11/2}$ midshell, shows a large signature splitting (>100 keV), indicating a significant triaxial deformation (γ∼-20°). Four ΔI=1 bands were observed at higher spins based on three-quasiparticle configurations. Strong M1 transitions and the lack of signature splitting imply that these bands are near prolate (γ∼0°) and thus contain one or more aligned $h_{11/2}$ protons from the lower midshell. In two of these bands, weak E2 crossover transitions were seen; measured B(M1;I→I-1)/B(E2;I→I-2) ratios were used to assign configurations. In addition, a ΔI=2 band with an enhanced moment of inertia was observed most probably built on the prolate ν$i_{13/2}$⊗[π$h_{11/2}$${]}^2$ configuration. Only one signature component of this configuration was seen because of the maximal signature splitting of the β-driving $i_{13/2}$ neutron orbital (Ω=(1/2).

The level scheme of ${}_{}{}^{98}{}_{}{}^{}\mathrm{Tc}$ has been investigated via the ${}_{}{}^{94}{}_{}{}^{}\mathrm{Zr}$${(}^7$Li,3nγ) reaction by in-beam γ spectroscopy and conversion-electron measurements. Gamma ray excitation functions, γ-γ coincidences, and $I_{\gamma }$(0°)/$I_{\gamma }$(90°) anisotropies have been measured in the energy interval $E^{\mathrm{*}}$${(\mathrm{}}^7$Li)=23–31 MeV. High spin states up to I=14 and $E^{\mathrm{*}}$=3200 keV have been observed. A ΔI=1 negative parity band based on the $I^{\pi }$${=8\mathrm{}}^{\mathrm{-}}$, 1091 keV state has been identified. The level scheme has been compared with the predictions of the two quasiparticles plus rotor model. The negative parity band is associated with the π̃$g_{9/2}$⊗ν̃$h_{11/2}$ intrinsic configuration space.

We have used the asymmetric two-center shell model to calculate the single-neutron energies in the ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{17}$,18O and ${}_{}{}^{13}{}_{}{}^{}$C${+\mathrm{}}^{17}$O collisions as a function of the internuclear distance. The periodic resonancelike structures observed in the angle-integrated inelastic cross sections for these systems can be understood in terms of the nuclear Landau-Zener promotion of a loosely bound valence neutron from the 1$d_{5/2}$ (Ω=(1/2) state to the 2$s_{1/2}$ state of the oxygen isotopes. Inclusion of the effects of a turning point in the Landau-Zener formula is found to give marked improvements in accounting for the observed angle-integrated inelastic cross sections for these systems. Intermediate structures in the cross sections are found to arise due to the energy-dependent oscillatory behavior of the partial cross sections. While some resonancelike peaks can be attributed to a single orbital angular momentum, many others arise due to the combined contributions of two or more angular momenta.

Target residues from the interaction of copper with 35 MeV/nucleon ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions have been studied by off-line γ-ray spectroscopy. Cross sections, average forward ranges, and forward-to-backward ratios were measured for 35 products. The data were used to obtain the isobaric yield distribution, the mass yield distribution, and the longitudinal momentum transfer. The results are compared with other studies of the interaction of copper with intermediate-energy projectiles and with various models.

The rotating frame approximation and the sudden limit are compared to exact calculations for nuclear collisions that excite high-spin states.

The Boltzmann-Uehling-Uhlenbeck model is extended to include fluctuations. The model is then applied to study both spectator and participant physics. The model is capable of providing a unified, parameter-free description of wide-ranging phenomena in intermediate energy heavy-ion collisions.

The structure of ${}_{}{}^{140}{}_{}{}^{}\mathrm{Nd}$ has been studied via the ${}_{}{}^{126}{}_{}{}^{}\mathrm{Te}$${(}^{18}$O,4n${)}^{140}$Nd and ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$${(}^{16}$O,4n${)}^{140}$Nd reactions at beam energies from 64 to 76 MeV and 72 to 76 MeV, respectively. In beam γ-ray spectroscopy techniques, including γ-ray excitation functions, γ-γ coincidences, and γ-ray angular distribution measurements, were used to construct a level scheme up to J=17 at an excitation energy of 6411 keV. Definite parity assignments were made up to the ${11}^{+}$ state. Two-particle configurations were calculated with a shell model and a modified surface delta interaction.

The rotational alignment of $h_{11/2}$ quasiparticles has been observed in the even-even ${}_{}{}^{138}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Nd}$ nuclei by means of heavy-ion fusion-evaporation reactions. The structures observed are compared to those found recently in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Nd}$. The ground-state bands of the ${}_{}{}^{136}{}_{}{}^{}\mathrm{Nd}$ and ${}_{}{}^{138}{}_{}{}^{}\mathrm{Sm}$ isotones (N=76) possess significant triaxial shapes (γ∼-25°). Rotational alignment of $h_{11/2}$ protons induces a shape change towards the prolate (γ=0°) shape, while $h_{11/2}$ neutron alignment induces a change towards the oblate (γ=-60°) collective shape. In the more deformed ${}_{}{}^{134}{}_{}{}^{}\mathrm{Nd}$ nucleus, band crossings are observed in both the ground-state band and the γ-vibrational band. The crossing in the ground-state band is attributed to $h_{11/2}$ protons, while a second band that feeds into both the ground-state band and the γ-vibrational band is built on the [$h_{11/2}$${]}^2$ neutron-aligned configuration. In addition, negative-parity sidebands built on two-quasiproton configurations were seen in these nuclei. The systematics of the proton and neutron alignments are discussed.

A formalism is developed for predicting two-particle correlations in terms of the final single-particle phase-space distributions which can be calculated from theoretical models. The ability to determine the phase-space distributions from experiment is discussed. It is shown that evaporation which characterizes the liquid phase and expansion which characterizes the gaseous phase have clear experimental signatures. An abrupt change in the behavior of the experimentally inferred lifetime is predicted near the threshold for the liquid-gas phase transition.

The independent yields, recoil properties, and forward-to-backward ratios (F/B) of iodine isotopes from the interaction of 240 MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ with ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ have been measured radiochemically by the thick-target/thick-catcher method. The isotopic yield distribution curve has been constructed and is found to consist of two overlapping Gaussians, peaking at A=126.5 and 133.8 with width parameters of 2.29 and 2.04 mass units, respectively. All the measured iodine isotopes had ranges of 7.7±0.4 mg/${\mathrm{cm}}^2$. The neutron-deficient products have F/B of 1.76±0.14, but the neutron-excessive products have F/B of only 1.09±0.06. The yield curve was analyzed with the liquid drop model and the recoil curve was analyzed by the standard two-step vector model; the results show that the neutron-deficient products are formed from nonequilibrium processes and the neutron-excessive products are formed from the normal low-energy fission process.

An analysis of the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$${(}^6$Li,dα${)}^{13}$C reaction in the collinear (${\theta }_{\mathrm{d}=0\mathrm{}}$°) and noncollinear (${\theta }_{\mathrm{d}=10\mathrm{}}$°,8°) geometry is made for two peaks observed in the deuteron energy spectrum and corresponding to excitation energies of 16.1 and 13.6 MeV in the ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ nucleus. It is shown that the reaction proceeds via a direct alpha-transfer process which populates doublets of interfering ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ levels. Spins, weights, and parities of these levels are obtained by means of a least square procedure.

We report on the measurement of level energies, lifetimes, γ-ray intensities, and angular distributions in ${}_{}{}^{73}{}_{}{}^{}\mathrm{Br}$, obtained in the reactions ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^{36}$Ar,3p) and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^{40}$Ca,α3p). The g factor of the 241 keV isomeric state (τ=50 ns) was determined to be g=1.31(9) from the Larmor precession in an external magnetic field. The fully aligned members of a rotationally aligned $g_{9/2}$ band were identified up to spin $I^{\pi }$${=(33/2\mathrm{}}^{+}$; the E2 transition strengths indicate a large prolate deformation decreasing from ${\beta }_2$=0.37(4) to ${\beta }_2$=0.33 at rotational frequency ħω≊0.45 MeV. The negative parity yrast bands with signatures α=±1/2 were established up to a probable spin of ${(37/2\mathrm{}}^{\mathrm{-}}$. The α=+1/2 yrast band shows a one quasiparticle to three quasiparticle band transition at the same frequency, probably associated with the alignment of two $g_{9/2}$ protons. The structure of ${}_{}{}^{73}{}_{}{}^{}\mathrm{Br}$, which is very similar to that of ${}_{}{}^{75}{}_{}{}^{}\mathrm{Br}$, has been interpreted with the Strutinsky-Bogolyubov cranking and deformed configuration mixing models.