The low-lying band structure of ${}_{}{}^{135}{}_{}{}^{}\mathrm{Nd}$ has been extended to higher spins using the ${}_{}{}^{112}{}_{}{}^{}\mathrm{Cd}$${(}^{27}$Al,p3nγ${)}^{135}$Nd and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$${(}^{24}$Mg,2p3nγ${)}^{135}$Nd reactions. Two distinct high-spin structures have been identified. The ΔJ=1 band built on the ν$h_{11/2}$${\left[514\right]\mathrm{}(9/2)\mathrm{}}^{\mathrm{-}}$ ground state was observed to have a band crossing at $J^{\pi }$${=(25/2)\mathrm{}}^{\mathrm{-}}$. This band crossing is associated with a loss of the moderate signature splitting found below the backbend. Cranked-shell model calculations suggest that this structure involves the alignment of a pair of $h_{11/2}$ protons and that the loss of signature splitting can be attributed to a shape change from a triaxial shape at low spins to a prolate axial shape above the backbend. A second ΔJ=1 band structure with no signature splitting was observed to be built on a $J^{\pi }$${=(17/2)\mathrm{}}^{\mathrm{}(+)\mathrm{}}$ state at 1954 keV. Values for the ratios of reduced transition rates B(M1; I →I-1)/B(E2; I→I-1) and B(M1; I→I-1)/B(E2; I→I-2) have been extracted from transitions in the two bands. Comparisons with theoretical predictions helped in the identification of the structure of the second ΔJ=1 band, which is thought to be based on a ν$h_{11/2}$⊗π$h_{11/2}$⊗π$g_{7/2}$ three-quasiparticle configuration.

Coulomb excitation of states in ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}$ up to J=(21/2) has been observed with 160-MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ and 617-MeV ${}_{}{}^{136}{}_{}{}^{}\mathrm{Xe}$ ions. Most of these states are grouped into three rotational-like bands based on the ${\mathrm{}(3/2)\mathrm{}}^{+}$ ground state, the ${\mathrm{}(1/2)\mathrm{}}^{+}$ first excited state, and the ${\mathrm{}(7/2)\mathrm{}}^{+}$ γ-vibrational-like state at 621 keV. The average deviation between experimental and theoretical energies for 18 states is 54 keV for the particle-asymmetric-rigid-rotor model and 66 keV for the interacting boson-fermion approximation model [limited to broken Spin(6) symmetry and only the $d_{3/2}$ orbital is considered]. The overall agreement of both model predictions with experimental γ-ray yields for the collective transitions within the ${\mathrm{}(3/2)\mathrm{}}^{+}$ band is quite good.

For interband transitions originating in the K${=(1/2)\mathrm{}}^{+}$ and ${\mathrm{}(7/2)\mathrm{}}^{+}$ bands, the interacting boson-fermion approximation model tends to underestimate the γ-ray yields by one to two orders of magnitude. In ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}$ there are eight Δ${\tau }_1$≥2 and six Δ${\sigma }_1$=1 transitions which are forbidden in the U(6/4) and U(6/20) supersymmetry schemes. The interacting boson-fermion approximation model tends to underestimate the B(E2) values of two of these transitions with moderate collectivity by at least one order of magnitude. The interband transition ${\mathrm{}(3/2)\mathrm{}}^{\mathcal{’}}$→(3/2) (Δ${\tau }_1$=2 transition) with moderate collectivity is not a special situation in ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}$ but a general feature in ${}_{}{}^{191}{}_{}{}^{}\mathrm{Ir}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$. For the remainder of the forbidden transitions in the supersymmetry schemes, the experimental B(E2) values are an order of magnitude smaller than the collective ones.

Both supersymmetry schemes and the broken Spin(6) model reproduce the collective E2 transitions with Δ${\tau }_1$=1 reasonably well. The triaxial rotor model description of the experimental energies and the collective E2 transitions is the most successful approach. The B(E3) for excitation of several negative-parity states in ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}$ is (3.3±2.0)B(E${3)}_{\mathrm{sp}}$.

I propose a fast algorithm for performing unconstrained phase-shift analyses of (low energy) heavy-ion elastic-scattering data. The method is applied, as an example, to ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{28}$Si elastic scattering at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=21.1\mathrm{}}$ MeV. A study of general properties of the error matrix is performed, and criteria for the feasibility of a model-independent analysis are discussed. Some recommendations for future experiments and model-dependent analyses are made.

Emission of fast particles in low-energy heavy-ion reactions is calculated using the exciton model. The initial state of the excitons is fixed by pure momentum-space considerations. By defining the projectile source and the target source as independent emitters of the fast particles, we calculate the angle-energy double-differential cross section. Angular dependence is obtained by fixing the total linear momenta of the projectile source and target source separately in addition to fixing their excitation energies. A linear-momentum-dependent level density is used for this purpose. This model is applied to several heavy-ion reactions whose energy is 10–20 MeV per particle. Our calculations reproduce the data for the high-energy part of the energy spectra well. Our model is one way of understanding the mechanism of the moving-source model.

As a first application of our fusion model, the dynamical fragmentation process of fusion and subsequent fission is analyzed in the reactions of 4.8–8 MeV/nucleon ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ on ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Fe}$, and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$. In this two step model, the colliding nuclei are first shown to be captured in the pockets behind the adiabatic interaction barriers and then the composite systems so formed, being strongly excited, fission adiabatically. The calculated capture cross sections agree reasonably well with the experiments and the mass distributions are systematically symmetric, independent of the choice of relative separation distance R and the large structure in the cranking masses. The symmetric mass fragmentation is a (dynamical) liquid drop effect and the peaks or other detailed structure in mass distributions depend on how the temperature would modify the masses and also on the dynamical coupling of mass asymmetry with the relative motion. This demands refined measurements of the fission data for larger mass asymmetry. The calculated critical angular momentum, which refers to the vanishing of the interaction barrier, in these reactions occurs at the incident energy greater than 8 MeV/nucleon. This suggests a possible importance of extending these experiments beyond their present energy limits.

The total reaction cross section ${\sigma }_R$ for ${}_{}{}^3{}_{}{}^{}$He${+\mathrm{}}^3$He has been obtained at laboratory bombarding energies of 17.9, 21.7, and 24.0 MeV by measuring the individual cross sections for production of protons, deuterons, tritons, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and α particles. The accuracy of the results is greatly improved by taking advantage of a novel method which depends on the symmetry about 90° in the center-of-mass system of the reaction cross sections for identical particles in the incoming channel. Use of this method reduces the range of energy and angle which must be measured for the continuous spectra of particles emitted in these multibody final states. In order of increasing energy, the values of ${\sigma }_R$ obtained in this experiment are 156.7±3.8, 250±14, and 296±12 mb. Individual cross sections contributing to ${\sigma }_R$ were also extracted. Implications of the measurements for resonating group calculations of ${}_{}{}^3{}_{}{}^{}$He${+\mathrm{}}^3$He scattering are examined.

The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(n,${\gamma }_0$${)\mathrm{}}^{13}$C excitation function at 90° has been measured for neutron energies from 6.5 to 18.5 MeV. Whereas previous measurements disagreed at the lower energies with a direct-semidirect capture calculation based on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,${\gamma }_0$${)\mathrm{}}^{13}$N data, the present results, especially when the uncertainty in absolute cross section is considered, indicate reasonable qualitative agreement with the calculation.

We report on recent advances made in employing realistic nucleon-nucleon forces for nucleon-deuteron elastic scattering. For the first time the Paris potential is used in all relevant partial waves through a separable expansion representing both its on-shell and off-shell properties. Here we present the neutron-deuteron total and differential cross sections below $E_{\mathrm{n}=20\mathrm{}}$ MeV as well as the vector-to-vector spin-transfer coefficients of the reaction ${}_{}{}^2{}_{}{}^{}$H(N→,d→${)}^1$H at $E_{\mathrm{N}=10\mathrm{}}$ MeV. These results may now be regarded as genuine predictions of the Paris potential for these particular observables of nucleon-deuteron scattering.

The neutron-proton capture differential cross section at 0° and 180° center of mass angles was measured at a neutron energy of 61 MeV. A new setup was designed which improved the signal over background ratio. The 0° cross section was found in agreement with the set of the other data around 60 MeV; the 180° cross section is significantly lower than the 0° cross section.

A spin-dependent expression is suggested for the emission rate of preequilibrium γ rays in the framework of the exciton model. The single-particle picture as well as the Brink-Axel hypothesis are adopted and the angular momentum coupling is treated in detail. The approach is consistent with the usual equilibrium γ emission rate and it also elucidates earlier nonspin preequilibrium results. The expression is completed by a fully spin-dependent formulation of the exciton model. As an illustrative example, the primary γ ray spectrum of the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$(n,γ) reaction at 14.6 MeV is analyzed. The impact of the angular momentum conservation on the γ ray spectrum as well as the nucleon emission is rather small. The preequilibrium γ emission is dominated by Δn=0 transitions between levels with low spins in the very first n-exciton stages of the reaction.

At real energies E, the derivation of the Lippmann-Schwinger integral equation from the Schrödinger equation involves various surface integrals at infinity in configuration space. Plausible assumptions about the values of these surface integrals made originally by Gerjuoy imply that the many-particle (n>2) Lippmann-Schwinger equation generally has nonunique solutions. This paper evaluates these surface integrals in the same one-dimensional three-body model (of McGuire) employed recently to demonstrate the nonuniqueness explicitly. The computed values of the surface integrals agree precisely with Gerjuoy’s hypotheses. These results further confirm the conclusion that the many-particle Lippmann-Schwinger equation has nonunique solutions in actual three-dimensional collisions, and support the belief that the aforesaid derivation of the real energy Lippmann-Schwinger equation is mathematically sound.

The ${}_{}{}^{76}{}_{}{}^{}\mathrm{Se}$(t,p${)}^{78}$Se reaction has been studied at an incident energy of 17 MeV. Excitation energies for 80 states (or groups of states) up to 6.16 MeV have been measured. Angular distributions have been obtained for 61 of them, below $E_x$=5.03 MeV. Comparison of the data with distorted-wave Born approximation calculations, using pure configurations for the transfer amplitudes, have enabled the L transfer (and hence $J^{\pi }$ value) to be determined for 58 of these states. Of these assignments, 52 are new.

Recently it has been suggested that as in the neutron deuteron problem the theoretically calculated spin-doublet S wave proton deuteron scattering length ${}_{}{}^2{}_{}{}^{}\mathrm{a}_{\mathrm{pd}}^{}{}_{}{}^{}$ is correlated with ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ binding energy. This strongly suggests that ${}_{}{}^2{}_{}{}^{}\mathrm{a}_{\mathrm{pd}\mathrm{\simeq }0}^{}{}_{}{}^{}$. In this paper we study various properties of the low energy trinucleon system including this correlation among scattering length and binding energy for the spin-doublet neutron deuteron and the proton deuteron systems in an ad hoc two-body model. The two-body potential models we employ have a long range tail of $r^{\mathrm{-}2}$ type and have been parametrized to produce the correct binding energies of ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and the correct s wave spin-doublet neutron deuteron scattering lengths ${}_{}{}^2{}_{}{}^{}\mathrm{a}_{\mathrm{nd}}^{}{}_{}{}^{}$. The present study predicts the low energy nucleon deuteron phase shifts and predicts the proton deuteron scattering length to be ${}_{}{}^2{}_{}{}^{}\mathrm{a}_{\mathrm{pd}\mathrm{\simeq }(0.15\mathrm{}\pm 0.1}^{}{}_{}{}^{}$) fm.

The reaction ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$(p,p’γ${)\mathrm{}}^{54}$Fe has been studied in the proton energy range 3.88 to 4.28 MeV. In all, 35 resonances were found. Angular distributions of the $2^{+}$→$0^{+}$ transition in ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ were measured at all the resonances and 20 ${\mathrm{}(5/2)\mathrm{}}^{+}$ states were identified. These are the major fragments of the isobaric analog of the ${\mathrm{}(5/2)\mathrm{}}^{+}$ 4.466 MeV state of ${}_{}{}^{55}{}_{}{}^{}\mathrm{Fe}$. From the angular distributions the intensities of the $s_{1/2}$, $d_{3/2}$, and $d_{5/2}$ inelastic partial waves were deduced. Capture γ ray spectra were measured for all of the ${\mathrm{}(5/2)\mathrm{}}^{+}$ resonances. The decay channels of the isobaric analog state fragments were subjected individually to fine structure analysis and compared using channel width correlations.

Proton cross sections for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ have been measured for elastic and inelastic scattering to the ${12}^{+}$, 6.10 MeV, ${12}_1^{\mathrm{-}}$, 6.43 MeV, ${12}_2^{\mathrm{-}}$, 7.06 MeV, and ${14}^{\mathrm{-}}$, 6.74 MeV states at $E_{\mathrm{p}=318\mathrm{}}$ MeV. We analyze the inelastic transitions in the distorted wave impulse approximation and use the previously published electron scattering results to constrain the wave functions in the unnatural parity calculations. A ${13}^{\mathrm{-}}$ state is discussed as an unresolved ‘‘contaminant’’ to the ${12}_1^{\mathrm{-}}$, 6.43 MeV state. Mixing between the ${12}^{\mathrm{-}}$ neutron and proton particle-hole configurations is found to reduce substantially the differences reported previously in observed proton and electron quenching factors. This results in greater quenching for the ${12}_2^{\mathrm{-}}$, 7.06 MeV state, and less quenching for the ${12}_1^{\mathrm{-}}$, 6.43 MeV state than was previously reported in (e,e’) analyses.

The energy spectra of α particles emitted from (p,α) reactions on ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{92}{}_{}{}^{}$,94,96,98,100Mo, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{106}{}_{}{}^{}\mathrm{Pd}$, and Ag with 18 MeV protons and on some of them with 15 MeV protons have been measured in order to clarify the shell and odd-even effects in the preequilibrium processes of (p,α) and (n,α) reactions. From the experimental results, it was found that there exists no appreciable odd-even effect on the target nuclei in energy spectra for the preequilibrium (p,α) reaction except for the spectra corresponding to the low lying states of the residual nuclei. Considerable change in the energy spectra in the energy region higher than 16 MeV has been observed for target nuclei around the magic number N=50. We have calculated the energy spectra, by using the knockout model introducing effective Q values, the pairing correlation and a modified uniform spacing model in which the uniform spacing levels have a wide spacing at the magic number. The shell effect of the gross structure of the energy spectra for the nuclei near the magic nuclei can be explained very well in terms of the present knockout model, although the fine structures of the spectra above 16 MeV which correspond to the low lying states or groups of the states of the residual nuclei cannot be explained so well.

The forward-to-backward asymmetry of neutrons emitted in the (γ,n) reactions on ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Cd}$ targets was measured for photons in the range of 20–30 MeV, where the isovector quadrupole giant resonance is expected to lie. The asymmetry was observed to increase from small values (≊0.2) to large ones (≊0.6 and 0.8) for ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Cd}$ and ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Pb}$, respectively. This phenomenon is interpreted as the interference between E1 and E2 amplitudes. From an analysis of the asymmetry the excitation energies of the E2 isovector resonances were estimated to be 23.5±1.5 MeV and 26.5±1.5 MeV for the Pb and Cd nuclei, respectively. The E2 isovector resonances are found to be considerably wider than the E1 resonances.

The ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$(α,t${)}^{60}$Ni reaction was used to populate states known to be of spin $8^{\mathrm{-}}$ by inelastic electron scattering measurements. Single-nucleon stripping spectroscopic factors obtained by comparison to exact-finite-range distorted-wave Born approximation calculations are compared to the fractions of M8 single-particle strength found from electron scattering for 10 transitions. Distributions of T=3 $8^{\mathrm{-}}$ strength were found to be rather similar in the two studies, with about 34% of the T=3 single-particle $8^{\mathrm{-}}$ stripping strength located.

The odd-odd nucleus ${}_{}{}^{72}{}_{}{}^{}\mathrm{Ga}$ has been studied via the ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$(d${,}^3$He${)}^{72}$Ga reaction at 25.2 MeV, with 9 keV resolution full width at half maximum, using a tandem accelerator and a split pole spectrometer. The spectroscopic factors are determined for 40 levels, some of which were previously unknown. All the observed levels have negative parity; limits for the spin value J are given and possible main configurations are suggested for some levels. The occupation numbers of the proton orbitals in ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$ have been determined: this nucleus appears in this respect as more similar to the heavier even Ge isotopes than to the lighter ones.

We carry out a distorted wave calculation of the radiation tail accompanying relativistic elastic electron scattering from the atomic nucleus using recently developed techniques for evaluating the radial matrix elements entering the calculation. The difficulty of calculating the high multipole components of the bremsstrahlung cross section is avoided by introducing a distortion factor that can be evaluated within the required accuracy with about 20 photon multipoles. The calculation still requires extensive computational time, so we compare our distorted wave results to an ad hoc technique of including distortion in the Bethe-Heitler result that is widely used. Surprisingly, we find that the ad hoc technique is very good for energy losses less than about 70% of the incident electron energy.