The $\mathrm{}(p,t)\mathrm{}$ reaction on ${}^{122}\mathrm{Sn}$ has been studied in a high resolution experiment at an incident proton energy of 26 MeV. The cross section angular distributions for transitions to 38 levels of ${}^{120}\mathrm{Sn}$ with an excitation energy up to $\sim 3500\mathrm{keV}$ have been measured. Distorted wave Born approximation analysis of experimental angular distributions using double-folded potential for the exit channel has been done. This has made it possible to confirm previous spin and parity values and to propose new assignments for a large number of states. A shell-model study of ${}^{120}\mathrm{Sn}$ has been performed using a realistic effective interaction derived from the Paris nucleon-nucleon potential. The calculations have been carried out within the framework of the seniority scheme including states with seniority up to 4. Comparison of the calculated and experimental spectra shows a one-to-one correspondence between levels up to about 2.7 MeV excitation energy and lends support to some of the spin-parity assignments given in this work.

The one-neutron nuclear breakup from the carbon isotopes ${}^{19}\mathrm{C}$ and ${}^{17}\mathrm{C},$ is calculated as an example of application of the theory of transfer to the continuum reactions in the formulation which includes spin coupling. The effect of the energy sharing between the parallel and transverse neutron momentum distributions is taken into account, thus resulting in a theory which is more general than sudden eikonal approaches. Both effects are necessary to understand properly the breakup from not too weakly bound $l_i>1\mathrm{}$ orbitals. Breakup which leads the core into an excited state below particle threshold is also considered. The core-target interaction is treated in the smooth cutoff approximation. By comparing to presently available experimental data we show how to make some hypothesis on the quantum numbers and occupancy of the neutron initial state. Possible ambiguities in the interpretation of inclusive cross sections are discussed.

Charmonium production and absorption in heavy ion collisions is studied with the ultrarelativisitic quantum molecular dynamics model. We compare the scenario of universal and time-independent color-octet dissociation cross sections with one of distinct color-singlet $J/\psi ,$ ${\psi }^{\prime }$, and ${\chi }_c$ states, evolving from small, color transparent configurations to their asymptotic sizes. Both purely hadronic scenarios are compared with the $\mathrm{pA}$ and $\mathrm{AB}$ data at SPS energies. The predicted rapidity dependence of $J/\psi$ suppression can be used to discriminate between the two scenarios experimentally. The importance of interactions with secondary hadrons and the applicability of thermal reaction kinetics to $J/\psi$ absorption are investigated. We discuss the effect of nuclear stopping and the role of leading hadrons. The dependence of the ${\psi }^{\prime }/J/\psi$ ratio on the model assumptions and the possible influence of refeeding processes are also studied.

We suggest two methods for the detection of the formation of disoriented chiral condensates $\left(\mathrm{D}\chi \mathrm{C}\right)$ in heavy ion collisions. We show that the variance in the number of charged pions (in a suitable range of momentum space) provides a signature for the observation of a disoriented chiral condensate. The signal should be observable even if multiple domains of $\mathrm{D}\chi \mathrm{C}$ form provided the average number of pions per domain is significantly larger than unity. The variance of the number of charged pions alone provides a signal which can be used even if the number of neutral pions cannot be measured in a given detector. On the other hand, the probability distribution in R, the proportion of neutral pions to all pions emitted in heavy ion collisions in certain kinematic regions, has been suggested as a signal of a disoriented chiral condensate. Here we note that the signature can be greatly enhanced by making suitable cuts in the data. In particular, we consider reducing the data set such that the k pions with lowest $p_T$ are all neutral. We find that, given such cuts, $〈R〉$ can be substantially different from $1/3$. For example, for a single $\mathrm{D}\chi \mathrm{C}$ domain without contamination due to incoherently emitted pions, $〈R〉$ is $3/5$ given the pion with lowest $p_T$ is neutral, and $5/7$ given the two pions with lowest $p_T$ are both neutral, etc. The effects of multidomain $\mathrm{D}\chi \mathrm{C}$ formation and noise due to incoherent pion emission can be systematically incorporated. Potential applications to experiments and their limitations are briefly discussed.

Data on $J/\psi$ production in inelastic proton-proton, proton-nucleus, and nucleus-nucleus interactions at $158A$ GeV are analyzed and it is shown that the ratio of mean multiplicities of $J/\psi$ mesons and pions is the same for all of these collisions. This observation is difficult to understand within current models of $J/\psi$ production in nuclear collisions.

The invariant mass distributions of the $\gamma \overrightarrow{n}p{\pi }^{-}{\pi }^0$ reaction have been determined from a measurement in the photon energy range $500-800\hspace{0.5em}\mathrm{MeV}$ at the MAMI Mainz accelerator with the large acceptance detector DAPHNE and using a deuterium target. At the higher photon energies, the invariant mass spectra of the $\left({\pi }^{-}{\pi }^0\right)$ system show a peak at larger invariant mass values, a signature of a $\pi \pi$ correlated emission in the final state.

The nucleus ${}^{49}\mathrm{Cr}$ has been studied using the reactions ${}^{28}\mathrm{Si}{(}^{28}\mathrm{Si},\alpha 2pn)$ at 115 MeV and ${}^{46}\mathrm{Ti}(\alpha ,n)$ at 12 MeV, respectively. A high-$K$ band with $K^{\pi }{=13/2\mathrm{}}^{+}$ has been identified, whose bandhead acts as an yrast trap for the low-lying levels with positive parity. This peculiar phenomenon is well reproduced by large-scale shell model calculations in the $\mathrm{pf}$ configuration space plus a proton hole in the ${1d}_{3/2}$ orbital. As an essential part of the work, lifetimes of some nonyrast states, as well as of a state in the $K^{\pi }{=5\mathrm{}}^{+}$ band in ${}^{50}\mathrm{Mn},$ have been determined using the Doppler shift attenuation method.

We use dispersion relations to reconstruct, in a model-independent way, the formation dynamics of heavy quarkonium from the experimental data on $e^{+}{e}^{-}\to \overline{Q}Q$ annihilation. We extract a distribution of formation times with a mean value for the $J/\psi ,$ $〈{\tau }_{J/\psi }〉=0.44\mathrm{}\mathrm{fm};$ and for the Υ, $〈{\tau }_{{\rm Y}}〉=0.32\mathrm{}\mathrm{fm}.$ The corresponding widths of these distributions are given by $\Delta {\tau }_{J/\psi }=0.31\mathrm{}\mathrm{fm}$ and $\Delta {\tau }_{{\rm Y}}=0.28\mathrm{}\mathrm{fm}.$ This information can be used as an input in modeling of heavy quarkonium production on nuclear targets.

We analyze the isoscalar vector current form factors of the nucleon using dispersion relations. In addition to the usual vector meson poles, we account for the $K\overline{K}$-continuum contribution by drawing upon a recent analytic continuation of $\mathrm{KN}$ scattering amplitudes. For the Pauli form factor all strength in the φ region is already given by the continuum contribution, whereas for the Dirac form factor additional strength in the φ region is required. The pertinent implications for the leading strangeness moments are demonstrated as well. We derive a reasonable range for the leading moments which is free of assumptions about the asymptotic behavior of the form factors. We also determine the $\phi \mathrm{NN}$ coupling constants from the form factor fits and directly from the $K\overline{K}\to N\overline{N}$ partial waves and compare the resulting values.

The nucleon strange vector and isoscalar electromagnetic form factors are studied using a spectral decomposition. The $K\overline{K}$ contribution to the electric and magnetic radii as well as the magnetic moment is evaluated to all orders in the strong interaction using an analytic continuation of experimental $\mathrm{KN}$ scattering amplitudes and bounds from unitarity. The relationship between nonresonant and resonant $K\overline{K}$ contributions to the form factors is demonstrated, and values for the vector and tensor $\phi N\overline{N}$ couplings are derived. The $K\overline{K}$ spectral functions are used to evaluate the credibility of model calculations for the strange quark vector current form factors.

We investigated the Gamow-Teller (GT) transitions in the ${}^{(7\mathrm{}}\mathrm{Li},$ ${}^7\mathrm{Be})$ reaction at $65A\mathrm{MeV}$ on light nuclei of ${}^6\mathrm{Li},$ ${}^{12}\mathrm{C},$ and ${}^{28}\mathrm{Si}.$ A one-step reaction process with a main contribution from the central force is dominant in the ${(}^7\mathrm{Li},$ ${}^7\mathrm{Be})$ reaction at forward angles. The cross sections observed at ${\theta }_L=0\mathrm{}°$ for the GT transitions were found to be proportional to the GT strengths deduced from the β decay.

Full finite-range distorted-wave Born approximation calculations have been performed using molecular, Michel, and normal optical potentials to analyze the angular distributions of cross sections for the 53 transitions populating the bound and unbound states of ${}^{28}\mathrm{Si}$ via the $(\alpha ,t)$ reaction. The parameters of these three potentials have been determined from analyses of the elastic scattering data in the entrance channel at the incident energy involved. The molecular and optical potentials are found to produce satisfactory fits to the data, but the Michel potential seems to be inadequate. For all three potentials in the entrance channel, the deduced l transfers for the transitions to the 15.02, 15.85, and 16.11 MeV states differ from the assignments previously reported. The extracted spectroscopic factors are compared with shell-model predictions.

Neutron resonances in ${}^{103}\mathrm{Rh}$ have been measured for neutron energies from 30 to 2000 eV using the time-of-flight method and the $(n,\gamma )$ reaction. The rhodium resonance spectroscopy is essential for the analysis of parity violation measurements recently performed on neutron resonances in ${}^{103}\mathrm{Rh}.$ Neutron scattering and radiative widths were determined, and orbital angular momentum assignments made with a Bayesian analysis. The $s$-wave and $p$-wave strength functions and average level spacings were determined.

Parity nonconservation (PNC) was studied in $p$-wave neutron resonances of ${}^{103}\mathrm{Rh}$ in the neutron energy range 30 to 490 eV. The helicity dependence of the neutron total cross section of rhodium was determined by capture measurements with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at the Los Alamos National Laboratory. A total of 32 $p$-wave resonances were studied and statistically significant longitudinal asymmetries were observed for resonances at $E_n=44.5,$ 110.8, 321.6, and 432.9 eV. A statistical analysis treating the PNC matrix elements as random variables yields a weak spreading width ${\Gamma }_w{=(1.42\mathrm{}}_{-0.59}^{+1.21\mathrm{}})\times {10}^{-7}\mathrm{eV}.$

In the spontaneous fission of ${}^{252}\mathrm{Cf},$ we observed that the population of spin $2^{+}$ in ${}^{136}\mathrm{Te}$ is closely correlated with the population of spin $4^{+}$ of its partner ${}^{114}\mathrm{Pd}.$ We attribute our results to the emission of two neutrons at scission carrying away two units of angular momentum and the yield is 0.06(2) per 100 spontaneous fission (SF) events whereas the two neutron normal fission yield is 0.12(3) per 100 SF for the ${}^{136}\mathrm{Te}$ and ${}^{114}\mathrm{Pd}$ pair. The yield for fission with four scission neutrons for ${}^{136}\mathrm{Te}$ and ${}^{112}\mathrm{Pd}$ is observed to be $\approx 0$ whereas the four neutron hot fission yield is 0.28(4) per 100 SF events.

We present an approach to obtain new forms of the nuclear electromagnetic current, which is based on an integral form of the continuity equation. The procedure can be used to restore current conservation in model calculations in which the continuity equation is not verified. In addition, it provides, as a particular result, the so-called Siegert’s form of the nuclear current, first obtained by Friar and Fallieros by extending Siegert’s theorem to arbitrary values of the momentum transfer. The new currents are explicitly conserved and permit a straightforward analysis of their behavior at both low and high momentum transfers. The results are illustrated with a simple nuclear model which includes a harmonic oscillator mean potential.

The freeze-out conditions in the light $(\mathrm{S}+\mathrm{S})$ and heavy $(\mathrm{Pb}+\mathrm{Pb})$ colliding systems of heavy nuclei at $160A\mathrm{GeV}/c$ are analyzed within the microscopic quark-gluon string model. We found that even for the most heavy systems particle emission takes place from the whole space-time domain available for the system evolution, but not from the thin “freeze-out hypersurface,” adopted in fluid dynamical models. Pions are continuously emitted from the whole volume of the reaction and reflect the main trends of the system evolution. Nucleons in $\mathrm{Pb}+\mathrm{Pb}$ collisions initially come from the surface region. For both systems there is a separation of the elastic and inelastic freeze-out. The mesons with large transverse momenta $p_t$ are predominantly produced at the early stages of the reaction. The low $p_t$ component is populated by mesons coming mainly from the decay of resonances. This explains naturally the decreasing source sizes with increasing $p_t,$ observed in Hanbury-Brown–Twiss interferometry. Comparison with $\mathrm{S}+\mathrm{S}$ and $\mathrm{Au}+\mathrm{Au}$ systems at $11.6A\mathrm{GeV}/c$ is also presented.

The idea that the reduction of the strange quark suppression in string fragmentation leads to the enhancement of strange particle yield in nucleus-nucleus collisions is applied to study the singly and multiply strange particle production in p-Pb and Pb-Pb collisions at $158A\hspace{0.5em}\mathrm{}\mathrm{GeV}/c.\mathrm{}$ In this mechanism the strange quark suppression factor is related to the effective string tension, which increases in turn with the increase of the energy, the centrality, and the mass of colliding system. The WA97 observation that the strange particle enhancement increases with the increasing centrality and the increasing strange quark content in multiply strange particles in Pb-Pb collisions with respect to p-Pb collisions was reproduced reasonably well.

It is found that the incremental alignments of superdeformed (SD) bands in nuclei in the $A\sim 150$ region exhibit a simple rule of additivity. This additivity is found to hold with good accuracy even for nuclei that differ by a large number of particles. The effect of neutron and/or proton band crossings and pairing correlations on this additivity are discussed. The additivity property of incremental alignments can be used to predict the energies of transitions in previously unknown SD bands and recent experimental results on SD bands in ${}^{147}\mathrm{Eu}$ are found to be in excellent agreement with the predicted values.

In this paper we derive quark model results for scattering amplitudes and equivalent low energy potentials for heavy meson pairs, in which each meson contains a heavy quark. This “BB” system is an attractive theoretical laboratory for the study of the nuclear force between color singlets; the hadronic system is relatively simple, and there are lattice gauge theory (LGT) results for $V_{\mathrm{BB}}\mathrm{}\left(r\right)\mathrm{}$ which may be compared to phenomenological models. We find that the quark model potential (after lattice smearing) has qualitative similarities to the LGT potential in the two $B^{*}{B}^{*}$ channels in which direct comparison is possible, although there is evidence of a difference in length scales. The quark model prediction of equal magnitude but opposite sign for $I=0\mathrm{}$ and $I=1\mathrm{}$ potentials also appears similar to LGT results at intermediate r. There may however be a discrepancy between the LGT and quark model $I=1\mathrm{}$ $\mathrm{BB}$ potentials. A numerical study of the two-meson Schrödinger equations in the $\left(b\overline{q}\right)\left(b\overline{q}\right)$ and $\left(c\overline{q}\right)\left(c\overline{q}\right)$ sectors with the quark model potentials finds a single BB “molecule,” in the $I=0\mathrm{}$ ${\mathrm{BB}}^{*}$ sector. Binding in other channels might occur if the quark model forces are augmented by pion exchange.