The ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$(t,α${)}^{178}$Lu reaction has been studied using beams of 17 MeV tritons from the McMaster University tandem Van de Graaff accelerator. Reaction products were analyzed with a magnetic spectrograph, and the resolution achieved for the alpha spectra was ∼20 keV (FWHM). Two-quasiparticle states in ${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$ involving the 9/$2^{+}$[624] target neutron coupled with the 7/$2^{+}$[404], 9/$2^{\mathrm{-}}$[514], and 1/$2^{+}$[411] proton orbitals were identified. The difference in ground-state (t,α) Q values for ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$ and ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$ components of the target, combined with the known masses of ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}$, ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$, and ${}_{}{}^{179}{}_{}{}^{}\mathrm{Hf}$, yields an improved value of -50 351±5 keV for the mass excess of ${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$. This result, combined with the two-quasiparticle assignments from the present work, has resolved the long-standing puzzle concerning the character and excitation energy of the well-known 23 min high-spin beta-decaying isomer in ${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$.

Forward angle (${\mathrm{\theta }}_{\mathrm{lab}}$=5°) differential cross sections for pion double charge exchange (${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$) on ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{62}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Ni}$ have been measured at a ${\mathrm{\pi }}^{+}$ kinetic energy of 293.4 MeV for reactions resulting in the double isobaric analog states. These cross sections are compared with the general trends seen in other double-charge-exchange reactions and with a generalized seniority model based on a sequential reaction mechanism. Results for nonanalog reactions involving the residual Zn ground states are also presented.

Mean lifetimes of levels in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ have been measured using the Doppler-shift-attenuation (DSA) method in conjunction with the reactions ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$${(}^{16}$O,pn${)}^{28}$Si and ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$(p,γ${)}^{28}$Si. The lifetime values were determined for 16 bound levels below the excitation energy of 10 MeV and for the 10.42-, 10.67-, 11.10-, and 11.51-MeV alpha unstable states, and the 12.99-MeV proton or alpha unbound state. The lifetimes of the three last levels are reported for the first time. The targets were prepared by implanting ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ into Ta, and ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ into Ta and Si substrates. The experimental stopping power of Ta for Si ions was determined by application of the inverted analysis of DSA data from the reaction ${}_{}{}^2{}_{}{}^{}\mathrm{H}$${(}^{28}$Si,pγ${)}^{29}$Si. Computer simulations with the Monte Carlo method and experimental stopping power were used in the DSA analysis. Experimental transition matrix elements, based on the measured mean lifetime values, are compared with predictions of the universal sd-shell model.

Level lifetimes were measured for the first time for the neutron-rich isotope ${}_{}{}^{78}{}_{}{}^{}\mathrm{Ge}$ by the fast electronic scintillation timing technique and B(E2) values were extracted. The energies of the low-lying states and the B(E2) values between the $0^{+}$ and $2^{+}$ states disclose a rapidly changing structure near N=40, followed by a stabilization, with ${}_{}{}^{74\mathrm{-}78}{}_{}{}^{}\mathrm{Ge}$ best understood as asymmetric rotors.

A comprehensive analysis is made of the experimental information on Gamow-Teller beta decay for the light (A≤18) nuclei. Experimental data on half-lives, Q values, and branching ratios are tabulated. Experimental logft values and beta-decay matrix elements are deduced from these data. The one-body-transition densities necessary to predict the beta-decay matrix elements are then calculated using a recently constructed shell-model Hamiltonian operating in the first four major shells. Using these parameters, effective Gamow-Teller operators are deduced for the 0p shell from a least-squares fit to 16 experimental matrix elements. The effective operators are used to calculate 83 decay matrix elements. Some specific decays are discussed.

The distribution of the discrete proton hole states of ${}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$ has been obtained within the hole-core vibrational scheme. The theoretical single-hole distribution pattern of these low-lying spin states has been discussed in the light of the recent experimental results based on the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$(p→,α) reaction. Side by side, the shell-model hole states of the ${}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$ have been compared with the hole states of the ${}_{}{}^{207}{}_{}{}^{}\mathrm{Tl}$ to prove the rigid collectivity of the ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ nucleus.

The negative parity energy levels of the even-even Ge isotopes with mass number between 64 and 76 are studied systematically by enlarging the model space of the interacting boson approximation model to include both collective and noncollective basis states. The basis states consist of ${\mathit{N}}_{\mathit{B}}$-1 sd-boson plus a f-boson configuration and ${\mathit{N}}_{\mathit{B}}$-1 sd boson plus a fermion pair configuration. The fermions are allowed to occupy the ${\mathit{f}}_{5/2}$ and ${\mathit{g}}_{9/2}$ single-particle orbitals, respectively. It was found that the negative parity energy levels of ${}_{}{}^{64\mathrm{-}76}{}_{}{}^{}\mathrm{Ge}$ nuclei can be described reasonably well. The intensities of the collective configuration in $3^{\mathrm{-}}$ states increase when going from nucleus ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ge}$ to nucleus ${}_{}{}^{72}{}_{}{}^{}\mathrm{Ge}$ and decrease from nucleus ${}_{}{}^{72}{}_{}{}^{}\mathrm{Ge}$ to nucleus ${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$. The B(E3;$3_1^{\mathrm{-}}$→$0_1^{+}$) values are calculated and compared with the available observed data.

It was recently reported that the well-known discrepancy between theoretical values of the moment of inertia and observed ones could be removed by a number-projection technique for the BCS states. To examine this problem, the exact calculation of the moment of inertia in the cranking model is performed in the ${}_{}{}^{160}{}_{}{}^{}\mathrm{Dy}$ isotope as a typical example. The Richardson method is applied to the exact treatment of the pairing correlations and recurrence formulas for computing various matrix elements in the cranking model are developed. The numerical results in ${}_{}{}^{160}{}_{}{}^{}\mathrm{Dy}$ indicate that the exact treatment hardly improves the BCS values of the moment of inertia and that the discrepancy with the observed values cannot be removed by the correction for the number nonconservation in the BCS wave functions.

A self-consistent study of the structure of the nuclear surface is done using the semi-infinite nuclear matter approximation. It is found that surface thickness strongly depends on the nuclear matter saturation density. It is also shown that the extended Thomas-Fermi calculations fail to reproduce this important feature. Its implication on the effective surface compressibility coefficient ${\mathit{K}}_{\mathit{s}}$, and on the extraction of the nuclear matter compressibility coefficient ${\mathit{K}}_{\mathrm{\infty }}$ from the measured finite nuclei values ${\mathit{K}}_{\mathit{A}}$, are also illustrated.

The solutions of the Vlasov equation based on the Walecka model applied to hot and dense nuclear matter are obtained and discussed. It is observed that the effective mass of scalar and vector mesons raises only slightly with temperature for T<180 MeV while the effective nucleon mass decreases. The collective longitudinal modes are obtained and the coupling between them is studied through the energy-weighted sum rule. At finite temperature it is found that the zero sound mode emerges in the continuum of particle-hole excitations.

Absolute total and differential cross sections for the reaction ${\mathrm{\pi }}^{+}$+d→p+p have been measured for pion energies from 3.7 to 20.5 MeV. A crossed-field velocity separator was used to enhance the purity of the pion beam, and a deuterated scintillator was used both as the target and to count the incident flux. The total cross sections are 4.0±0.5, 4.4±0.2, 4.2±0.2, 4.2±0.2, and 4.8±0.3 mb for incident pion energies of 3.7, 5.0, 9.6, 15.2, and 20.5 MeV, respectively. The measured differential cross sections indicate the presence of p-wave strength at all energies studied and are in good agreement with recent measurements for the reaction n+p→d+${\mathrm{\pi }}^0$ near threshold and a recent parametrization of the total and differential cross sections for the process.

The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,γ${)}^{16}$O E2 cross section is calculated in the generator coordinate method where ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ is described by three α particles located on the apexes of an equilateral triangle. Distortion effects in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ wave functions are taken into account, and the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ wave functions are defined by a mixing of α${+}^{12}$C($0^{+}$,$2^{+}$) configurations. The good quantum numbers are restored through angular momentum projection. We compute quadrupole transition probabilities between low-energy ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ states, and the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,γ${)}^{16}$O E2 cross sections to the ground and $2_1^{+}$ states. At 300 keV, we find an S factor equal to 0.09 MeV b.

A natural Cu target was irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN. The 105 MeV/c p¯ beam was completely slowed down inside a thick target producing many radioactive products. Starting shortly after the irradiation and continuing for about one year, this residual activity was counted using off-line gamma-ray spectroscopy techniques. The yields of 40 radioactive reaction products were determined. The charge dispersion and complete mass yield distribution were deduced using a well-established fitting procedure. The shape of the mass yield and, in particular, the average number of removed nucleons, the dispersion of the mass distribution, and its logarithmic slope characterize the average energy deposited during the antiproton-nucleus interaction. We compare these quantities with similar data gathered for other projectiles interacting with natural Cu targets. These comparisons indicate that the average excitation energy of the system formed after the stopped antiproton annihilation is similar to the average excitation energy following 2-GeV proton interaction with Cu nuclei. The observed mass distribution is also compared with the intranuclear cascade calculations.

We have measured the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${\gamma }^{\mathrm{*}}$,${\mathrm{\pi }}^{\mathrm{-}}$p${)}^{11}$${\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ cross section using virtual bremsstrahlung at three points at invariant masses of 1444 and 1530 MeV. At low neutron initial momentum (${\mathit{p}}_{\mathit{m}}$≊60 MeV/c) and large ${\mathit{N}}^{\mathrm{*}}$ momentum (${\mathit{p}}_{\mathit{N}}^{\mathrm{*}}$≊750 MeV/c) the measured cross section is at or below the distorted wave impulse approximation (DWIA) calculation. At larger initial momentum (${\mathit{p}}_{\mathit{m}}$≊220 MeV/c) and smaller ${\mathit{N}}^{\mathrm{*}}$ momentum (${\mathit{p}}_{\mathit{N}}^{\mathrm{*}}$≊500 MeV/c), the measured cross section is almost twice as large as the DWIA calculation. This discrepancy might be due to ${\mathit{N}}^{\mathrm{*}}$-nucleus interactions.

The production of neutral pions in the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{27}$Al at 94 MeV/nucleon was studied with a multidetector, which includes 180 ${\mathrm{BaF}}_2$ modules. Kinetic energy spectra for several laboratory angles were measured. The total cross section for neutral pion production was deduced. Results were compared with previous findings on charged pions from the same reaction at the same energy and with the prediction of a dynamical model based on the numerical solution of the Boltzmann-Nordheim-Vlasov equation.

Pulsed-beam time-of-flight techniques are used in a transmission measurement with a continuous spectrum of neutrons to determine neutron total cross sections with good precision up to 600 MeV. Neutrons are produced by spallation of the 800 MeV proton beam from the Los Alamos Meson Physics Facility accelerator incident on a thick, heavily shielded tungsten target at the Weapons Neutron Research facility at Los Alamos National Laboratory. Transmission measurements were completed for fifteen elements with 9≤A≤209 and three isotopically enriched samples of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. Principal features of the experiment are the intensity and time structure of the neutron source, tight collimation of the neutron beam line, good geometry, rapid cycling of the samples, stable electronics, and a small, fast neutron detector. Errors due to counting statistics were generally less than 1% for each of several hundred energy bins for each target. The measurements represent steps in the development of a neutron-nucleus optical potential at intermediate energy and important input for the clarification of isovector effects in the nucleon-nucleus interaction. The data also provide insight into the long-standing discussion of mean free paths of the nucleon in the nucleus.

We report nuclear excitation functions for the reactions ${}_{}{}^{79}{}_{}{}^{}[$(p,n)+(d,2n)${]}^{79}$Kr, ${}_{}{}^{81}{}_{}{}^{}[$(p,n)+ (d,2n)${]}^{81}$Br, ${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$(d,p${)}^{82}$Br, and ${}_{}{}^{127}{}_{}{}^{}[$(p,n)+(d,2n)${]}^{127}$Xe. The measurements were made from reaction threshold to 17 MeV with the Lawrence Livermore National Laboratory’s Tandem Van de Graaff accelerator using the stacked-foil method. The ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}$(d,2n${)}^{79}$Kr and the ${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$ excitation functions are the first reported. The targets consisted of the halides dispersed in the plastic Kapton. The activated targets were assayed using γ counting and mass spectrometry. We found that we had to remeasure the gamma intensities for the ${}_{}{}^{79}{}_{}{}^{}\mathrm{Kr}$ decay. The excitation functions were modeled using the Hauser-Feshbach statistical-model code stapre, using the exciton preequilibrium model. We found a preference for the back-shifted (BS) level density prescription over the use of the Gilbert-Cameron prescription. For BS, the constant K, governing the transition to equilibrium, was taken as 500 to 700 ${\mathrm{MeV}}^3$. These values gave preequilibrium fractions consistent with those we obtained from ion-recoil range studies of light ion reactions. In general the modeling agreed well with experiment. For the deuteron induced reactions, we had to allow for deuteron breakup using a microscopic breakup fusion approach developed by Udagawa and Tamura. Our analysis of the stripping reaction, ${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$(d,p${)}^{82}$Br, by this procedure is especially noteworthy.

The (p,n) reaction has been measured for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ targets at 290 MeV for a laboratory angle of 20.4° and at 420 MeV for a laboratory angle of 24.0°. This paper presents new cross section data and analyzing powers at excitation energies near the quasifree peak. The data are compared with recently developed nonrelativistic calculations and with extended relativistic calculations that include random phase approximation correlations.

Mass, energy, and angular distributions have been measured for A=6–30 fragments formed in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$${+}^{28}$Si reaction at bombarding energies of 117.4 and 198.5 MeV. The data are compared with calculations which account for the reaction dynamics in terms of an intranuclear cascade, followed by statistical decay of the excited residues. General agreement between the data and calculations is found for the spectral shapes and mass distributions; however, the experimental angular distributions are significantly more forward peaked than predicted. This suggests a failure of the model to account satisfactorily for momentum transfer in the collision stage. These results extend linear momentum systematics for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ projectiles near the Fermi velocity, to significantly lower target mass than previously measured. Implications of the data to questions of cosmic ray astrophysics and radiation damage in microelectronic circuits are also discussed.

We present a model of one-neutron transfer reactions appropriate for cases in which one of the collision partners is deformed. The model considers rotational excitation due to the Coulomb field in the entrance channel, neutron transfer between the two nuclear surfaces at the distance of closest approach, and additional rotational excitation in the final channel. The Coulomb excitation processes are described within the sudden-limit approximation using classical-limit theory, and the transfer is described in terms of spectroscopic amplitudes obtained with the particle-rotor model. We have applied this model of transfer to the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${+}^{161}$Dy and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$${+}^{161}$Dy one-neutron pickup reactions, cases for which data are available. The calculations indicate that transfer into both ground and two-quasiparticle excited bands takes place and that the distribution of population in the ground band and two-quasiparticle states is in reasonable agreement with the data.