High-spin states of ${}^{143}\mathrm{Nd}$ have been studied using $\gamma -\gamma$ and $\gamma$-conversion electron coincidences. The measurement of 16 new transitions and 8 new conversion coefficients allow revision of the high-spin portion of the level scheme and the determination of parities of six levels for the first time. While the yrast states up to $J=43/2\mathrm{}$ can be described using the weak coupling of an $f_{7/2}$ neutron to the ${}^{142}\mathrm{Nd}$ core nucleus, the new experimental results suggest that weak coupling breaks down above $J=43/2.\mathrm{}$ This behavior may signal that the closed $N=82\mathrm{}$ neutron shell of ${}^{142}\mathrm{Nd}$ is broken above $J=16.\mathrm{}$

The stable nucleus ${}^{177}$Hf was studied with time-correlated particle-$\gamma$-$\gamma$ techniques following the reaction ${}^{176}\mathrm{Yb}{(}^9\mathrm{Be},\alpha {4n)}^{177}$Hf at a beam energy of 70 MeV. New high-spin states include extensions to three-quasiparticle bands based on the $K^{\pi }{=23/2\mathrm{}}^{+}$ and ${25/2}^{-}$ configurations, together with a new band associated with the $K^{\pi }{=19/2\mathrm{}}^{-}$, $T_{1/2}=56\mathrm{}$ μs isomer. Moreover, the band based on the five-quasiparticle $T_{1/2}$=51 minute, $K^{\pi }{=37/2\mathrm{}}^{-}$ state has been found, and a band assigned to a new $K^{\pi }{=39/2\mathrm{}}^{+}$, five-quasiparticle state. Values of ${(g}_K-g_R{)/Q}_0$ agree well with the configuration assignments made to new and previously known bands. Comparison with multiquasiparticle calculations that incorporate a Lipkin-Nogami treatment of pairing correlations with blocking, suggests that all of the most favored three- and five-quasiparticle states have been observed. The dependence of the $\gamma$-ray intensities on the angular yields of the $\alpha$ particles suggests that the population arises from two entry distributions: one associated with complete fusion of the beam with the target, the other with incomplete fusion.

A $K^{\pi }{=8\mathrm{}}^{-}$ collective rotational band has been established upon the 6 $\mu$s isomeric state in the very neutron-deficient nucleus ${}^{138}\mathrm{Gd}.$ The band was observed using a technique involving the correlation of $\gamma$-ray transitions across the isomeric state. The single-particle configuration of the isomer has been deduced from the $\Delta I=2\mathrm{}$ to $\Delta I=1\mathrm{}$ intensity branching ratios. In addition, a series of other $\gamma$-ray transitions were observed which are reasoned to be part of a higher-lying four quasiparticle structure which decays through the $K^{\pi }{=8\mathrm{}}^{-}$ isomeric state. The properties of the $K^{\pi }{=8\mathrm{}}^{-}$ band are discussed in relation to the systematic properties of $K^{\pi }{=8\mathrm{}}^{-}$ bands in the neighboring $N=74\mathrm{}$ isotones.

Shell model calculations are carried out for nuclei with $148<~A<~152$ assuming ${}_{64}^{146}{\mathrm{Gd}}_{82}$ as an inert core. A weak coupling scheme is used to analyze the experimental data and the calculated results. The essential role of the proton intruder state $\pi h_{11/2},$ the large energy gaps between the neutron single-particle states $\nu f_{7/2}$ and the others, and the weak proton-neutron interaction provide a simple and interesting picture for the spectra and wave functions, i.e., the independent nucleon-pair motion and the corresponding homologous structure. The proton pairs in $\pi h_{11/2},$ $\pi d_{3/2},$ and $\pi s_{1/2}$ orbitals and the neutron pair in $\nu f_{7/2}$ or $\nu f_{7/2}{h}_{9/2}$ orbitals in nuclei ${}_{68}^{150,152}{\mathrm{Er}}_{82,84}$ and ${}_{66}^{150}{\mathrm{Dy}}_{84}$ are moving almost independently in the mean field provided by the core. Therefore, the yrast states below 5.3 MeV of these nuclei can be finely explained as the compositions of the excitations of these independent nucleon pairs. The negative parity levels of nuclei ${}_{66}^{149}{\mathrm{Dy}}_{83},$ ${}_{65}^{149}{\mathrm{Tb}}_{84},$ ${}_{67}^{151}{\mathrm{Ho}}_{84},$ and ${}_{69}^{153}{\mathrm{Tm}}_{84}$ can be well interpreted in terms of the concept of homologous states, i.e., the level structures in nuclei ${}_{66}^{149}{\mathrm{Dy}}_{83},$ ${}_{65}^{149}{\mathrm{Tb}}_{84},$ ${}_{67}^{151}{\mathrm{Ho}}_{84},$ and ${}_{69}^{153}{\mathrm{Tm}}_{84}$ are homologous to those of the parent structure in nuclei ${}_{66}^{148}{\mathrm{Dy}}_{82},$ ${}_{64}^{148}{\mathrm{Gd}}_{84},$ ${}_{66}^{150}{\mathrm{Dy}}_{84},$ and ${}_{68}^{152}{\mathrm{Er}}_{84},$ respectively. The level structure of the nucleus ${}_{68}^{151}{\mathrm{Er}}_{83},$ homologous to that of parent states in the nucleus ${}_{68}^{150}{\mathrm{Er}}_{82},$ is predicted and quite impressive in our full shell model calculation. This desires experiments to verify. The conditions for the onset of the independent nucleon-pair motion and the homologous structure are discussed in detail.

We investigate the independent quasiparticle picture for superdeformed nuclei of the mass-190 region, which is expected to lead to additivity in certain physical quantities. Obvious deviations from additivity are found from both experimental data and projected shell model calculations. The cause of the deviation can be decomposed and identified through this model. Our study suggests that the independent quasiparticle picture may not be fully appropriate for this mass region.

The calculation of complicated transition matrix elements between multiquasiparticle states can be essentially simplified by transforming them in a canonical form. This method allows the extension of the basis space of generator coordinate studies aiming to include orthogonal quasiparticle excitations into the commonly considered basis set of collective states. Furthermore, it is shown that the neglect of the exchange contribution of multipole forces may lead to dangerous pole terms in nondiagonal matrix elements.

Using the extended Thomas-Fermi plus Strutinsky integral approximation to the Skyrme-Hartree-Fock method we show that provided the nuclear mass data are well fitted extrapolations to neutron-rich and superheavy nuclei are quite insensitive to generalizations intended to simulate the main effects of relativistic mean-field theory. In particular, as far as energy-related quantities are concerned, it is sufficient to use the conventional spin-orbit force.

The experimental data of the magnetic dipole moments of low-lying states in odd-odd $N=Z$ nuclei, which has increased recently by a factor of 2, are revisited within the simple shell model, taking the wave functions to be of the form ${\Psi }_{\mathrm{core}}\mathrm{}(J=0,T=0\mathrm{})\mathrm{}{\Psi }_{\mathrm{np}}\mathrm{}(J,T=0\mathrm{}).$ Good agreement with the updated experimental data is obtained within the $\mathrm{jj}$-coupling scheme ${\Psi }_{\mathrm{np}}[{\mathrm{}\left(\mathrm{nlj}\right)\mathrm{}}^{2}J,(T=0\mathrm{}\left)\mathrm{}\right],$ using the Schmidt values for the $g$ factor and also by using effective $g$ factor deduced from nearby odd-$A$ nuclei. We have also carried out a calculation of μ within the $\mathrm{LS}$-coupling scheme ${\Psi }_{\mathrm{np}}[{\mathrm{}(1/2)\mathrm{}}^2{S\left(\mathrm{nl}\right)\mathrm{}}^{2}L,J,(T=0\mathrm{}\left)\mathrm{}\right]$ and also obtained good agreement with data. The success of these simple models in reproducing the experimental data is discussed.

Negative energy states are included explicitly in relativistic Brueckner-Hartree-Fock (RBHF) calculations by a medium-modified Gross spectator equation approach. An important advantage is the unambiguous determination of the Dirac and momentum structure of the RBHF self-energy. Applications to infinite symmetric nuclear matter are discussed. Qualitatively our results are close to conventional RBHF calculations. In detail, however, significant differences occur. They are related to the fact that a large part of the vector repulsion is generated dynamically by the explicit treatment of the negative energy states. The equation of state is stiffer and the momentum dependence of the self-energy components is stronger than found in a reference calculation without intermediate negative energy states. The density dependence of effective mean-field coupling constants is found to change considerably when Dirac-sea contributions are included.

With the supersymmetry model being extended to include many-body interactions and with the single-particle Routhian being taken into account, the identical superdeformed (SD) bands ${}^{152}\mathrm{Dy}\left(1\right)$ and ${}^{151}\mathrm{Tb}\left(2\right)$ are investigated. The calculated results agree with experimental data quantitatively well. It indicates that the supersymmetry with a many-body interaction is probably a source of the identical SD bands. Meanwhile to describe various aspects of the identical bands, the single-particle Routhian should also be taken into account.

Measurements of gamma-ray spectra, following the thermal neutron fission of ${}^{235}\mathrm{U}$ have been made using a high purity germanium detector at the University of Massachusetts Lowell (UML) Van de Graaff facility. The gamma spectra were measured at delay times ranging from 0.2 s to nearly 10 000 s following the rapid transfer of the fission fragments with a helium-jet system. On the basis of the known gamma transitions, forty isotopes have been identified and studied. By measuring the relative intensities of these transitions, the relative yields of the various precursor nuclides have been calculated. The results are compared with the recommended values listed in the ENDF/B-VI fission product data base (for the lifetimes and the relative yields) and those published in the Nuclear Data Sheets (for the beta branching ratios). This information is particularly useful for the cases of short-lived fission products with lifetimes of the order of fractions of a second or a few seconds. Independent yields of many of these isotopes have rather large uncertainties, some of which have been reduced by the present study.

Analyzing powers for $\overrightarrow{p}\overrightarrow{p}\mathrm{pn}{\pi }^{+}$ were measured for the first time close to threshold at beam energies that yield maximum pion momentum fractions $\left(\eta \equiv p_{\mathrm{c}.\mathrm{m}.\mathrm{}}^{\max }{/m}_{\pi }c\right)$ of $\eta =0.22,$ 0.42, and 0.50, and enable a decomposition of the low order partial waves. Cross sections were measured at seven different beam energies with $\eta =0.07,$ 0.17, 0.22, 0.28, 0.34, 0.42, and 0.50. The analysis shows that pion $s$-wave channels dominate the reaction. The $p$-wave channel containing the Δ resonance contributes, at $\eta =0.22,$ less than one-tenth of the total cross section and less than one-third of the total cross section at $\eta =0.42\mathrm{}$ and 0.50. The nonresonant $p$-wave channel contributes less than 1% of the cross section at these three energies.

The neutron capture cross section of ${}^{26}\mathrm{Mg}$ was measured relative to the known gold cross section at thermonuclear energies using the fast cyclic activation technique. The experiment was performed at the 3.75 MV Van-de-Graaff accelerator, Forschungszentrum Karlsruhe. The experimental capture cross section is the sum of resonant and direct contributions. For the resonance at $E_{\mathrm{n},\mathrm{l}\mathrm{a}\mathrm{b}}=220\mathrm{}$ $\mathrm{keV}$ our new results are in disagreement with the data from Weigmann, Macklin, and Harvey [Phys. Rev. C 14, 1328 (1976)]. An improved Maxwellian averaged capture cross section is derived from the new experimental data taking into account $s$- and $p$-wave capture and resonant contributions. The properties of so-called potential resonances which influence the $p$-wave neutron capture of ${}^{26}\mathrm{Mg}$ are discussed in detail.

This paper presents a large solid angle measurement of the positive pion absorption cross section on ${}^4\mathrm{He}$ and its decomposition into partial channels. The total absorption cross sections at incident pion kinetic energies of $T_{{\pi }^{+}}=70,$ 118, 162, and 239 MeV are $35\pm 5,$ $52\pm 4,$ $51\pm 5,$ and $27\pm 2$ mb, respectively. These values are lower than those reported in some previous experiments. At all pion energies a large fraction of the absorption cross section is due to multinucleon channels.

We report on the results of experiments performed to investigate the Au+Au 35 MeV/nucleon reaction. The reaction products generated in the disassembly of the unique source formed in central collisions and those coming from the decay of the quasiprojectile in peripheral and midperipheral ones (five different impact parameters) were identified through a careful data selection based on the study of energy and angular distributions. The excitation energies of the fragment sources have been extracted through a calorimetric method and by means of a comparison with model calculations. The nuclear temperatures of these decaying systems have been measured from the relative isotopic abundances and, also for central collisions, from the relative populations of excited states. The temperatures of the quasiprojectile disassembling systems are slowly increasing going towards smaller impact parameter. The relationship between temperature and excitation energy seems to be almost independent of the characteristics of the emitting source. The extracted caloric curve shows a slow monotonic increase with increasing excitation energy. A comparison with data derived from Au fragmentation at much higher incident energies is discussed.

${}^{12}\mathrm{C}(\overrightarrow{p},d{\pi }^{+}{)}^{11}\mathrm{B}$ has been investigated in the quasifree region at energies of 370 and 500 MeV. For each energy, measurements were made at the four angle combinations of $({\theta }_{d,\mathrm{left}},{\theta }_{\pi ,\mathrm{right}})$ equal to (15°, 30°), (15°, 55°), (25°, 30°), and (25°, 55°). In addition to strong excitation of the g.s. ${3/2}^{-}$ state, the 2.12 MeV ${1/2}^{-}$ and 5.02 MeV ${3/2}^{-}$ states are also excited with appreciable strength. Furthermore, a broad continuum at an excitation energy of about 20 MeV, corresponding to the ${1s}_{1/2}$ hole state is prominently seen. The pion differential cross section distributions exhibit maxima when the recoil nucleus momenta are at a minimum. Analyzing powers were obtained over the range of pion energies investigated. Several measurements for the ${}^2\mathrm{H}(\overrightarrow{p},d{\pi }^{+})n$ reaction are also reported. The results are compared with plane-wave impulse approximation and distorted-wave impulse approximation calculations.

The reaction ${}^{10}\mathrm{B}(\gamma ,p)$ has been studied using tagged photons of mean energies $E_{\gamma }=57.6\mathrm{}$ and 72.9 MeV. Angular distributions and derived single-particle momentum distributions for protons leading to the ground state of ${}^9\mathrm{Be}$ and higher excited states are compared to various calculations made using model parameters constrained by ${}^{10}\mathrm{B}{(e,e}^{\prime }{p)}^9\mathrm{Be}$ and ${}^9\mathrm{Be}{(p,p}^{\prime }{)}^9\mathrm{Be}$ measurements. The effects of varying final-state interactions (including channel couplings) and meson exchange currents are considered. A sizable discrepancy between direct-knockout calculations and the experimental results is observed. If meson exchange currents are included in an approximate fashion, a good description of the ${}^{10}\mathrm{B}(\gamma {,p}_0{)}^9\mathrm{Be}$ data is found.

γ rays emitted in coincidence with charged particles have been measured in the collision ${}^{12}{\mathrm{C}+}^{64}\mathrm{Ni}$ at 94.7 MeV. The γ spectrum detected in coincidence with evaporation residues has been fitted using the statistical code CASCADE and does not show clear evidence for nonstatistical emission. γ spectra measured in coincidence with fast, forward emitted α particles show a contribution around 10 MeV which has been interpreted as being due to preequilibrium dipole emission in the first stages of the collision. The presence of this nonstatistical yield has been explained performing theoretical calculations based on the Boltzmann-Nordeim-Vlasov equation.

Excitation functions were measured for the ${}^{52}\mathrm{Cr}{\mathrm{}(n,2n)\mathrm{}}^{51}\mathrm{Cr}$, ${}^{52}\mathrm{Cr}{\mathrm{}(n,p)\mathrm{}}^{52}\mathrm{V}$, ${}^{53}\mathrm{Cr}{\mathrm{}(n,p)\mathrm{}}^{53}\mathrm{V}$, ${}^{53}\mathrm{Cr}{\mathrm{}(n,np+pn+d)\mathrm{}}^{52}\mathrm{V}$, ${}^{54}\mathrm{Cr}{\mathrm{}(n,p)\mathrm{}}^{54}\mathrm{V}$, ${}^{54}\mathrm{Cr}{\mathrm{}(n,np+pn+d)\mathrm{}}^{53}\mathrm{V}$, and ${}^{54}\mathrm{Cr}(n,\alpha {)}^{51}\mathrm{Ti}$ reactions from 9 to 21 MeV. Use was made of the activation technique in combination with high-resolution $\gamma$-ray spectrometry. Monoenergetic neutrons produced via the ${}^2\mathrm{H}{\mathrm{}(d,n)\mathrm{}}^3\mathrm{He}$ and ${}^3\mathrm{H}{\mathrm{}(d,n)\mathrm{}}^4\mathrm{He}$ reactions were used to irradiate samples of metallic chromium, ${}^{52}{\mathrm{Cr}}_2{\mathrm{O}}_3$, ${}^{53}{\mathrm{Cr}}_2{\mathrm{O}}_3$, and ${}^{54}{\mathrm{Cr}}_2{\mathrm{O}}_3$. The neutron fluence rates were determined via the ${}^{27}\mathrm{Al}{\mathrm{}(n,p)\mathrm{}}^{27}\mathrm{Mg}$, ${}^{27}\mathrm{Al}(n,\alpha {)}^{24}\mathrm{Na}$, ${}^{56}\mathrm{Fe}{\mathrm{}(n,p)\mathrm{}}^{56}\mathrm{Mn}$, and ${}^{93}\mathrm{Nb}{\mathrm{}(n,2n)\mathrm{}}^{92m}\mathrm{Nb}$ monitor reactions. Short-lived activities were investigated using a pneumatic sample transport system. Statistical model calculations taking into account preequilibrium effects were performed for all the reactions using a consistent set of model parameters. The experimental excitation functions helped appreciably to resolve the discrepancies in evaluated data files. Good agreement was found between our experimental data and the new model calculations.

Five rotational bands involving intruder and/or extruder orbitals have been observed in the doubly-odd nucleus ${}^{132}\mathrm{Pr}.$ One of them is observed for the first time. The properties of the new band are similar to those of the excited highly deformed band of ${}^{134}\mathrm{N}\mathrm{d},$ which has a configuration involving one $i_{13/2}$ neutron at low frequency that is crossed at high frequency by a configuration with two $i_{13/2}$ neutrons. This behavior indicates that the stepwise occupation of $\nu i_{13/2}$ intruder orbitals is an efficient mechanism for building high angular momentum in the light $A\sim 130$ nuclei.