We discuss an event-by-event fluctuation analysis of particle production in heavy ion collisions. We compare different approaches to the evaluation of the event-by-event dynamical fluctuations in quantities defined on groups of particles, such quantities as mean transverse momentum, transverse momentum spectra slope, strength of anisotropic flow, etc. The direct computation of the dynamical fluctuations and the subevent method are discussed in more detail. We also show how the fluctuations in different variables can be related to each other.

A large reduction of the ${\rho }^0$ mass in the nuclear medium is reported, inferred from dipion photoproduction spectra in the 1 GeV region, for the reaction ${}^3\mathrm{He}(\gamma ,{\pi }^{+}{\pi }^{-})X$ with a 10% duty factor tagged-photon beam and the TAGX multiparticle spectrometer. The energy range spanned $(800\mathrm{}<~E_{\gamma }<~1120\hspace{0.5em}\mathrm{MeV})$ lies mostly below the free-${\rho }^0$ production threshold, a region which is believed to be sensitive to modifications of light vector-meson properties at nuclear-matter densities. The values of the ${\rho }^0$ mass extracted from the Monte Carlo fitting of the data were $m_{{\rho }^0}^{*}=642\mathrm{}\pm 40,$ $669\pm 32,$ and $682\pm 56\hspace{0.5em}\mathrm{MeV}{/c}^2$ for $E_{\gamma }$ in the 800–880, 880–960, and 960–1040 MeV regions, respectively. These values were independently corroborated in a qualitative fashion by a measured, assumption-free, kinematical observable. This mass shift, far exceeding current mean-field-driven theoretical predictions, may be suggestive of a nucleonic source of modification or of a bound state in the nuclear mean field.

We search t-matrix poles for $\Lambda N-\Sigma N$ coupling interactions using two soft core models of the Nijmegen group which bind the hypertriton at the correct binding energy, and hard core models which are still influential in hypernuclear physics. To treat the hard core potentials, a useful method for calculating the off-shell t-matrix is proposed. We find poles close to the $\Sigma N$ threshold in the second or third quadrant of the complex plane of the $\Sigma N$ relative momentum. The relation between the poles and the shape of the $\Lambda N$ elastic total cross section is discussed based on a so-called uniformization by which two-channel t-matrices become single-valued on a complex valuable. We also find poles near the $\Lambda N$ threshold. These are correlated to the S-wave $\Lambda N$ scattering lengths, the values of which have yet to be determined.

The level scheme of ${}^{103}\mathrm{Pd}$ has been reconstructed using high-fold $\gamma$-ray coincidence data obtained with the EUROGAM-2 spectrometer in the ${}^{70}\mathrm{Zn}{(}^{36}\mathrm{S},3n)$ reaction at $E=130\mathrm{}\mathrm{MeV}.$ New spins and excitation energies are given for levels in the strongly coupled positive parity bands. Four high-spin bands are discussed in terms of terminating configurations using Nilsson-Strutinsky cranking calculations. One of them, having valence-space configuration, is observed up to its predicted terminating state of $I^{\pi }{=65/2\mathrm{}}^{+}.$ Another band, which is possibly observed up to its terminating state at $I>\mathrm{}40,$ is assigned to have a $2p-2h$ core-excited configuration.

We have calculated the differential cross section of $\pi d$ elastic scattering at $180°$ for incident pion laboratory momenta between 0.8 and 3.2 $\mathrm{GeV}/c.\mathrm{}$ We have applied a relativistic model which includes single- and double-scattering terms. The results show a strong dependence on the chosen deuteron model and on the cutoff parameter of the $\pi N$ off-shell amplitude. The rapid falloff with energy of the experimental data can be reproduced by our model calculation. Details of the cross section are described better by the inclusion of the double-scattering term.

The importance of an explicit treatment of continuum channels in the ${(d,}^2\mathrm{He})$ charge-exchange reaction is investigated. The continuum channel effects are clarified by a comparison of the full three-body results with calculations which use the distorted waves approximation to the three-body model. Continuum channel effects are shown to reduce the calculated ${}^{12}\mathrm{C}{(d,}^2\mathrm{He}{)}^{12}\mathrm{B}(\mathrm{g}.\mathrm{s}.\mathrm{})$ differential cross section at 270 MeV incident deuteron energy. This reduction is consistent with that from an earlier ad hoc modification of the absorptive content of an assumed ${}^2\mathrm{He}$ optical potential within distorted waves Born approximation calculations.

Evaporation residues (ER) of $Z=34\mathrm{}–42$ were measured in coincidence with emitted protons, deuterons, tritons, and α particles for the reaction ${}^{84}\mathrm{Kr}{+}^{27}\mathrm{Al}$ at a ${}^{84}\mathrm{Kr}$ bombarding energy of 1260 MeV. Our study demonstrates the presence of a strong preequilibrium component in the reaction yield. The assumption of a forward center-of-mass angular distribution for the emission of energetic protons and α, following full momentum transfer, gives the best description of the observed experimental data. This description differs substantially from the one provided by prevailing models of incomplete fusion.

We compute for the first time the decay width of $\Lambda$-hypernuclei in a relativistic mean-field approximation to the Walecka model. Due to the small mass difference between the $\Lambda$-hyperon and its decay products—a nucleon and a pion—the mesonic component of the decay is strongly Pauli blocked in the nuclear medium. Thus, the in-medium decay becomes dominated by the nonmesonic, or two-body, component of the decay. For this mode, the $\Lambda$-hyperon decays into a nucleon and a spacelike nuclear excitation. In this work we concentrate exclusively on the pionlike modes. By relying on the analytic structure of the nucleon and pion propagators, we express the nonmesonic component of the decay in terms of the spin-longitudinal response function. This response has been constrained from precise quasielastic $(\overrightarrow{p},\overrightarrow{n})$ measurements done at LAMPF. We compute the spin-longitudinal response in a relativistic random-phase-approximation model that reproduces accurately the quasielastic data. By doing so, we obtain hypernuclear decay widths that are considerably smaller—by factors of 2 or 3—relative to existing nonrelativistic calculations.

The properties of isospin-asymmetric nuclear matter have been investigated in the framework of the extended Brueckner-Hartree-Fock approximation at zero temperature. Self-consistent calculations using the Argonne $V_{14}$ interaction are reported for several values of the asymmetry parameter $\beta =\left(N-Z\right)/A,$ ranging from symmetric nuclear matter to pure neutron matter. The binding energy per nucleon fulfills the ${\beta }^2$ law in the whole asymmetry range. The symmetry energy is calculated for different densities and discussed in comparison with other predictions. At the saturation point it is in fairly good agreement with the empirical value. The present approximation, based on the Landau definition of quasiparticle energy, is investigated in terms of the Hugenholtz–Van Hove theorem, which is proved to be fulfilled with a good accuracy at various asymmetries. The isospin dependence of the single-particle properties is discussed, including mean field, effective mass, and mean free path of neutrons and protons. The isospin effects in nuclear physics and nuclear astrophysics are briefly discussed.

The $(n,\gamma )$ cross section of the unstable isotope ${}^{179}\mathrm{Ta}$ ${(t}_{1/2}=1.82\mathrm{}\pm 0.03\mathrm{yr})$ has been measured at thermal energies by means of the activation method. The ${}^{180}\mathrm{Hf}\mathrm{}(p,2n)\mathrm{}$ reaction was used for the production of ${}^{179}\mathrm{Ta},$and thin samples of 4 and 20 ng were obtained by the electrospraying technique. From irradiations with and without Cd absorbers the thermal cross section ${\sigma }_{\mathrm{th}}=932\mathrm{}\pm 62\mathrm{b}$ and the corresponding resonance integral $I_{\mathrm{res}}=1216\mathrm{}\pm 69\mathrm{b}$ could be determined.

The anomalously high activation yield of the ${11/2}^{-}$ isomeric states in odd-$A$ Te isotopes in the $(n,\gamma ),$ $(\gamma ,n),$ and $(\gamma ,{\gamma }^{\prime })$ reactions could be understood by the funneling of the initial gateway states through the lowest isolated ${5/2}^{-}$ state. The peculiar deexcitation mode is governed by favored $M1,$ $E2\mathrm{}$ transitions inside the family of negative-parity states built in accordance with IBFM calculations by a coupling of the dominant ${1h}_{11/2}$ and $3p$ configurations to the neighboring bosonic even-even core.

We calculate dilepton production for the reactions ${\pi }^{-}\mathrm{C}$ and ${\pi }^{-}\mathrm{Pb}$ at 1.3 GeV within a semiclassical BUU transport model and compare our results to a previously published calculation. We show that a modified treatment of the $\rho$ meson production and propagation gives substantially different results. We, furthermore, discuss uncertainties related to the electromagnetic decay of the $\rho$ meson and the elementary ${\pi }^{-}\overrightarrow{N}{e}^{+}{e}^{-}X$ channels.

By using the Gerasimov-Drell-Hearn (GDH) sum rule and an isobaric model of kaon photoproduction, we calculate contributions of kaon-hyperon final states to the magnetic moment of the proton and the neutron. We find that the contributions are small. The approximation of ${\sigma }_{{\mathrm{TT}}^{\prime }}$ by ${\sigma }_T$ clearly overestimates the value of the GDH integral. We find a smaller upper bound for the contributions of kaon-hyperon final states to the proton’s anomalous magnetic moment in kaon photoproduction, and a positive contribution for the square of the neutron’s magnetic moment.

The proton-neutron quasiparticle random phase approximation (pn-QRPA) is extended to include next to leading order terms of the QRPA harmonic expansion. The procedure is tested for the case of a separable Hamiltonian in the SO(5) symmetry representation. The pn-QRPA equation of motion is solved by using a boson expansion technique adapted to the treatment of proton-neutron correlations. The resulting wave functions are used to calculate the matrix elements of double-Fermi transitions.

A study of three-body resonances has been performed in the framework of configuration-space Faddeev equations. The importance of keeping a sufficient number of terms in the asymptotic expansion of the resonance wave function is pointed out. We investigated three neutrons interacting in selected force components taken from realistic $\mathrm{nn}$ forces. Three-neutron resonance pole trajectories connected to artificially enhanced $\mathrm{nn}$ forces could be found. The final pole positions corresponding to the actual force strengths could not be found due to the onset of numerical instabilities. The numerically reliable results achieved, however, make it likely, that three-neutron resonance energies will have large imaginary parts and are therefore physically not interesting. A straightforward application of complex scaling to three-nucleon systems with realistic forces could not be controlled numerically.

The lifetimes of twelve low spin excited states have been measured in ${}^{71}\mathrm{Ge}$ using the Doppler shift attenuation method in the ${}^{71}\mathrm{Ga}(p,n\gamma )$ reaction at 3.0 and 3.5 MeV incident energy. New interacting boson-fermion model calculations for this nucleus account well for the properties of all its levels known up to about 1.5 MeV excitation.

The low-energy structure of the $Z=51,\hspace{0.5em}N=82\mathrm{}$ nuclide ${}^{133}\mathrm{Sb}$ has been studied through a high-sensitivity investigation of the ${\beta }^{-}$ decay of ${}^{133}\mathrm{Sn}$. As a result, more than 70 new excited states have been observed and about 100 $\gamma$-ray transitions have been placed in the level scheme. Regarding the single-proton states, the $d_{3/2}$ level was found at 2439.5 keV and for the $h_{11/2}$ state at 2791.3 keV, a half-life of 11.4(4.5) ps has been measured. Levels at higher energies are interpreted as core-coupled states with the $g_{7/2}$ odd proton coupled to the excited states of the ${}^{132}\mathrm{Sn}$ core. A detailed discussion of the beta decay is presented.

The electron-capture decay of the ${}^{168}{\mathrm{Lu}}^m$ ${(T}_{1/2}=6.7\mathrm{}\hspace{0.5em}\min ,$ $J^{\pi }{=3\mathrm{}}^{+})$ isomer was studied with high purity sources, obtained by using a new radiochemical method consisting of fast continous on-line separation of reaction products. A complex spectrum composed of about 200 $\gamma$ rays was observed. From these, 162 transitions were assigned to a level scheme of 39 excited levels of ${}^{168}\mathrm{Yb}$, primarily by $\gamma -\gamma$ coincidence spectroscopic measurements. About 60 transitions were placed for the first time and $>90\%$ of the decay intensity was clearly identified. The structure of the levels directly fed by the electron-capture decay was reviewed as particle-hole excitations of the core.

Results from a $4\pi$ solid angle measurement of the inclusive reaction $({\pi }^{+},{\pi }^0)$ on ${}^2$H, ${}^3$He, and ${}^4$He at incident pion energies of $T_{{\pi }^{+}}=70\mathrm{}$, 118, 162, 239, and 330 MeV are presented. The single charge exchange total cross sections were determined, and are compared to previous results and simple models of $\pi$–few-nucleon interactions. On the helium isotopes a strong damping of the cross sections in the $\Delta \mathrm{}\left(1232\right)\mathrm{}$ energy region is observed. Total cross sections of the breakup reaction ${\pi }^{+}{+}^2$H $\to {\pi }^{+}\mathrm{pn}$ are also given.

High quality analyzing powers for the ${\pi }^{-}\overrightarrow{p}\to {\pi }^{0}n$ reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing $\pi N$ single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the $\Delta \mathrm{}\left(1232\right)\mathrm{}$ resonance. They will also be helpful for constraining the evaluation of the pion-nucleon $\sigma$ term from the scattering amplitudes.