The transverse mass $m_t$ distributions for deuterons and protons are measured in $\text{Pb}+\text{Pb}$ reactions near midrapidity and in the range $0<m_t-m<1.0\left(1.5\right)\text{GeV}∕c^2$ for minimum bias collisions at $158A\text{GeV}$ and for central collisions at 40 and $80A\text{GeV}$ beam energies. The rapidity density $dn∕dy$, inverse slope parameter $T$ and mean transverse mass $⟨m_t⟩$ derived from $m_t$ distributions as well as the coalescence parameter $B_2$ are studied as a function of the incident energy and the collision centrality. The deuteron $m_t$ spectra are significantly harder than those of protons, especially in central collisions. The coalescence factor $B_2$ shows three systematic trends. First, it decreases strongly with increasing centrality reflecting an enlargement of the deuteron coalescence volume in central $\text{Pb}+\text{Pb}$ collisions. Second, it increases with $m_t$. Finally, $B_2$ shows an increase with decreasing incident beam energy even within the SPS energy range. The results are discussed and compared to the predictions of models that include the collective expansion of the source created in $\text{Pb}+\text{Pb}$ collisions.

The minimal supersymmetric standard model with gauge mediated supersymmetry breaking and trilinear $R$-parity violation is applied to the description of neutrinoless double $\beta$ decay. A detailed study of limits on the parameter space coming from the $B\to X_s\gamma$ processes by using the recent CLEO results is performed. The importance of two-nucleon and pion-exchange realizations of $0\nu \beta \beta$ decay together with gluino and neutralino contributions to this process is addressed. We have deduced new limits on the trilinear $R$-parity breaking parameter ${\lambda }_{111}^{\prime }$ from the nonobservability of $0\nu \beta \beta$ in several medium and heavy open-shell nuclei for different gauge mediated breaking scenarios. In general, they are stronger than those known from other analyses. Also some studies with respect to the future $0\nu \beta \beta$ projects are presented.

Absolute partial cross sections for production of 45 discrete $\gamma$ rays in the ${}^{238}\mathrm{U}\left(n,xn\gamma \right)$ reactions with $x⩽4$ are reported for incident-neutron energies in the range $1\text{MeV}<E_n<100\text{MeV}$. A germanium-detector array for $\gamma$-ray detection and the “white”-neutron source at LANSCE∕WNR were used for the measurement. The energy of the incident neutrons was determined using the time-of-flight technique. The data are compared with previous measurements and with theoretical predictions up to $E_n=30\text{MeV}$ from the GNASH reaction model. The combination of experimental results with theoretical calculations provides a means to deduce the ${}^{238}\mathrm{U}\left(n,n^{\prime }\right)$ reaction cross section.

Jet quenching is considered to be one of the signatures of the formation of quark-gluon plasma. In order to investigate the jet quenching, it is necessary to detect jets produced in relativistic heavy ion collisions, determine their properties, and compare those with the jets one obtains in hadron-hadron or $e^{+}\text{−}{e}^{-}$ collisions. In this work, we propose that calculation of flow parameters may be used to detect and characterize jets in relativistic heavy ion collisions.

The $\sigma$-exchange and $f_2$-exchange mechanisms for $\rho$ meson photoproduction are reexamined. Then the commonly employed $\sigma$-exchange amplitude is revised by using the recent information from the analyses on the $\rho \to {\pi }^0{\pi }^0\gamma$ decay and the $\sigma NN$ coupling constant from Bonn potential. Instead of relying on the Pomeron-$f$ proportionality assumption, the $f_2$ meson exchange amplitude is established from an effective Lagrangian which is constructed from the tensor structure of the $f_2$ meson. Phenomenological information together with tensor meson dominance and vector meson dominance assumptions are used to estimate the $f_2$ coupling constants. As a first step to improve the current theoretical models, we have also explored the effects due to the uncorrelated $2\pi$-exchange amplitude with $\pi N$ intermediate state. This leading-order $2\pi$-exchange amplitude can be calculated using the coupling constants determined from the study of pion photoproduction and the empirical width of $\rho \to \pi \pi$ decay. In comparing with the existing differential cross section data, we find that a model with the constructed $2\pi$, $\sigma$, and $f_2$ exchanges is comparable to the commonly used $\sigma$-exchange model in which the $\sigma$ coupling parameters are simply adjusted to fit the experimental data. We suggest that experimental verifications of the predicted single and double spin asymmetries in the small $\mid t\mid \left(<2{\text{GeV}}^2\right)$ region will be useful for distinguishing the two models and improving our understanding of the nonresonant amplitude of $\rho$ photoproduction. Possible further improvements of the model are discussed.

We examine the impact of adding a Coulomb term to a constrained system of 147 particles interacting via a Lennard-Jones potential, finding that the inclusion of the Coulombic interaction produces a shift, but no qualitative changes in the thermodynamical properties of the system. We also performed the systems’ characterization from a morphological point of view.

The feasibility of measuring angular correlations of $\gamma$ rays emitted from intermediate-energy exotic nuclei to determine multipolarities of $\gamma$-ray transitions is shown. The applicability of $\gamma \text{−}\gamma$ angular correlation measurements is discussed for various excitation mechanisms.

The possibility of appearance of spin polarized states in strongly asymmetric nuclear matter is analyzed within the framework of a Fermi liquid theory with the Skyrme effective interaction. The zero temperature dependence of the neutron and proton spin polarization parameters as functions of density is found for $SLy4$ and $SLy5$ effective forces. It is shown that at some critical density strongly asymmetric nuclear matter undergoes a phase transition to the state with the oppositely directed spins of neutrons and protons while the state with the same direction of spins does not appear. In comparison with neutron matter, even small admixture of protons strongly decreases the threshold density of spin instability. It is clarified that protons become totally polarized within a very narrow density domain while the density profile of the neutron spin polarization parameter is characterized by the appearance of long tails near the transition density.

The results of experiments designed to synthesize element 115 isotopes in the ${}^{243}\mathrm{Am}+{}^{48}\mathrm{Ca}$ reaction are presented. With a beam dose of $4.3\times {10}^{18}$ $248\text{−}\text{MeV}$ ${}^{48}\mathrm{Ca}$ projectiles, we observed three similar decay chains consisting of five consecutive $\alpha$ decays, all detected in time intervals of about $20\mathrm{s}$ and terminated at a later time by a spontaneous fission with a high-energy release (total kinetic energy $\sim 220\text{MeV}$). At a higher bombarding energy of $253\text{MeV}$, with an equal ${}^{48}\mathrm{Ca}$ beam dose, we registered a different decay chain of four consecutive $\alpha$ decays detected in a time interval of about $0.5\mathrm{s}$, also terminated by spontaneous fission. The $\alpha$ decay energies and half-lives for nine new $\alpha$-decaying nuclei are given. The decay properties of these synthesized nuclei are consistent with consecutive $\alpha$ decays originating from the parent isotopes of the new element 115, ${}^{288}115$ and ${}^{287}115$, produced in the $3n$- and $4n$-evaporation channels with cross sections of about $3\text{pb}$ and $1\text{pb}$, respectively. The radioactive properties of the new odd-$Z$ nuclei $(105–115)$ are compared with the predictions of the macroscopic-microscopic theory. The experiments were carried out at the U400 cyclotron with the recoil separator DGFRS at FLNR, JINR.

The proton decay of the highly deformed odd-odd nucleus ${}^{130}\mathrm{Eu}$ has been observed by bombarding a ${}^{58}\mathrm{Ni}$ target with a beam of $425\text{MeV}$ ${}^{78}\mathrm{Kr}$ ions. Fusion evaporation residues were separated in-flight using the Argonne fragment mass analyzer and implanted into a double-sided silicon strip detector. ${}^{130}\mathrm{Eu}$ decays by the emission of a proton with energy $E_p=1020\left(15\right)\text{keV}\left[Q_p=1028\left(15\right)\text{keV}\right]$ and half-life $t_{1∕2}={0.90}_{-0.29}^{+0.49}\text{ms}$. The transition is assigned to a highly deformed $\left({\beta }_2\sim 0.3\right)J^{\pi }=1^{+}$ ground-state configuration by comparing the decay rate with a new theoretical formalism for deformed odd-odd nuclei. These results clearly demonstrate the sensitivity of the proton decay rate to the spectator neutron configuration.

The recent experiment with a new array detector aiming the investigation of halo neutron pair pre-emission in Si(${}^{11}\mathrm{Li}$, fusion) is described. A new approach for testing the true $n\text{−}n$ coincidences against cross-talk has been worked out. An experimental evidence for residual correlation of the pre-emitted halo neutrons is presented. The results obtained in building the $nn$ correlation functions by using the available denominators are discussed. A recent iterative method for calculation of the intrinsic correlation function was also applied. An experiment for precise measurement of the intrinsic $nn$ correlation function is proposed.

Effects of the momentum dependence of the symmetry potential in nuclear reactions induced by neutron-rich nuclei at Rare Isotope Accelerator (RIA) energies are studied using an isospin- and momentum-dependent transport model. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy $E_{sym}\left(\rho \right)$ lead to significantly different predictions on several $E_{sym}\left(\rho \right)$-sensitive experimental observables. The momentum dependence of the symmetry potential is thus critically important for investigating accurately the equation of state and novel properties of dense neutron-rich matter at RIA.

The nucleus ${}^{122}\mathrm{Ba}$ possesses an excitation energy ratio $R_{4∕2}=E\left(4_1^{+}\right)∕E\left(2_1^{+}\right)=2.90$ matching exactly the value predicted by the recently discussed $X\left(5\right)$ solution of the Bohr-Hamiltonian. Besides the ground state band, other low-spin positive-parity bands of ${}^{122}\mathrm{Ba}$ are unknown hampering detailed comparison to the theory. Excited low-spin states of ${}^{122}\mathrm{Ba}$ have been studied by in-beam $\gamma \gamma$-coincidence spectroscopy with the ${}^{112}\mathrm{Sn(}{}^{12}\mathrm{C,}2n\text{)}{}^{122}\mathrm{Ba}$ reaction. A level structure was observed which we interpret as a part of the $\gamma$ band of ${}^{122}\mathrm{Ba}$.

We investigate the two-neutron transfer modes induced by $(t,p)$ reactions in neutron-rich oxygen isotopes. The nuclear response to the pair transfer is calculated in the framework of continuum quasiparticle random phase approximation (cQRPA). The cQRPA allows a consistent determination of the residual interaction and an exact treatment of the continuum coupling. The $(t,p)$ cross sections are calculated within the distorted wave Born approximation approach and the form factors are evaluated by different methods: macroscopically, following the Bayman and Kallio method, and fully microscopically. A significant part of the cross section corresponds to a high-lying collective mode built entirely upon continuum quasiparticle states.

The mass and the charge changing cross sections recently measured in inverse kinematics are investigated microscopically in the framework of Glauber model using the ground state point proton∕neutron densities obtained in the relativistic mean field∕relativistic Hartree-Bogoliubov approach. As illustrative examples, explicit results for the nuclei spanning different regions of the periodic table, incident on ${}^{12}\mathrm{C}$, hydrogen, and $-{\text{CH}}_2$ targets are presented. The present study gives an excellent account of the experiment.

In the present study we generalize the self-consistent Hartree-Fock-Bogoliubov (HFB) theory formulated in the coordinate space to the case which incorporates an arbitrary mixing between protons and neutrons in the particle-hole $\left(p\text{−}h\right)$ and particle-particle ($p\text{−}p$ or pairing) channels. We define the HFB density matrices, discuss their spin-isospin structure, and construct the most general energy-density functional that is quadratic in local densities. The consequences of the local gauge invariance are discussed and the particular case of the Skyrme energy-density functional is studied. By varying the total energy with respect to the density matrices the self-consistent one-body HFB Hamiltonian is obtained and the structure of the resulting mean fields is shown. The consequences of the time-reversal symmetry, charge invariance, and proton-neutron symmetry are summarized. The complete list of expressions required to calculate total energy is presented.

Neutron-rich Zr and Mo isotopes were populated as fission fragments produced by the ${}^{238}\mathrm{U}\left(\alpha ,\mathit{f}\right)$ fusion-fission reaction. The level schemes of these nuclei have been extended beyond the first band crossing region, which can be ascribed to the $h_{11∕2}$ neutron pair alignment. The spin alignment and signature splitting for the $\nu h_{11∕2}$ orbitals in term of triaxiality is addressed. The crossing frequency of the aligned bands in even Zr and Mo isotopes can be reproduced well by calculations using the cranked shell model. Compared to the Zr isotopes, band crossings in Mo isotopes shift to a lower rotational frequency due to the emerging importance of the $\gamma$ degree of freedom. Within the framework of particle-rotor model, the difference in the signature splitting observed for the $\nu h_{11∕2}$ bands between the odd Zr and Mo isotopes can be attributed to the triaxial degree of freedom in the Mo isotopes. The surprising shift of the band crossing to a higher rotational frequency in ${}^{106}\mathrm{Mo}$ is interpreted as a manifestation of the deformed subshell closure at $N=64$.

An extended Holstein-Primakoff mapping which incorporates both single- and double-fermion mappings is used in the context of thermofield dynamics to study the next-to-leading order of the $1∕N$ expansion at finite temperature. For the Lipkin-Meshkov-Glick model it is shown that the extended mapping naturally leads to the correct Fermi statistics both in leading and next-to-leading order.

High spin states of ${}^{134}\mathrm{Ce}$ have been studied using an array of 8 Compton suppressed clover detectors and a multiplicity filter consisting of $14\text{NaI}\left(\mathrm{T}1\right)$ detectors. Two new $\Delta I=1$ bands $B4$ and $B5$ with strong intraband magnetic dipole transitions have been established. The crossover $E2$ transitions have been observed in the $B4$ band and lifetimes of levels, both in $B4$ and $B5$ bands, have been measured using the Doppler shift attenuation method. The measured $B\left(M1\right)$ values are large for the $B4$ band, yet the measured $B\left(M1\right)∕B\left(E2\right)$ ratios are nearly constant with increasing frequency and do not support the magnetic rotation character. The $B4$ band also exhibits a small gain in alignment at a higher frequency suggesting an upbending and a band crossing. These features are sought to be explained in terms of two closely lying configurations $A:\pi {\left(g_{7∕2}\right)}^2\otimes \nu \left(h_{11∕2}{d}_{3∕2}\right)$ and $B:\pi {\left(h_{11∕2}\right)}^2\otimes \nu \left(h_{11∕2}{d}_{3∕2}\right)$, which have a small and a moderate deformation, respectively. The tilted axis cranking (TAC) calculations suggest that configuration $B$ crosses the configuration $A$ with a small alignment gain and mixing between the two may explain the observed features. The measured $B\left(M1\right)$ values deduced from the lifetimes for the $B5$ band show a decrease with increasing spin which is a characteristic feature of magnetic rotation bands. The results of the TAC calculations explain the $B5$ band very well by using the four-quasiparticle configuration $\pi \left(g_{7∕2}{h}_{11∕2}\right)\otimes \nu \left(h_{11∕2}^{-2}\right)$ and establish it as a magnetic rotational band.