We propose a handy formula for calculating the formation cross sections for optimal bombarding energies for transactinides (superheavy elements). By means of the proposed formula the cross sections for asymmetric and symmetric cold fusion reactions (one-neutron-out reactions) are calculated. The fusion barrier and its position are calculated by using the folding heavy-ion potential that for spherical reaction partners has the form of a seventh-order polynomial of the radial coordinate with built-in dependence on the thickness of the nuclear surface, as well as on the separation energy of the least bound nucleon. Possibilities of further experimental exploitation of cold fusion in producing the superheavy nuclei are briefly discussed.

We calculate the two-photon exchange amplitude for the elastic electron-proton scattering in the framework of dispersion relations. The imaginary part of the amplitude is determined by unitarity. Since in the unitarity relation intermediate states are on shell, off-shell form factors are not needed for the calculation. The real part is then evaluated using analytical properties of the amplitude. The expression for the elastic contribution to the amplitude, obtained in our approach, differs from the results of traditional calculations with on-shell form factors. Nevertheless, numerically the difference is minor for $Q^2$ up to 6 GeV${}^2$.

Applying a variational multiparticle-multihole configuration mixing method whose purpose is to include correlations beyond the mean field in a unified way without particle number and Pauli principle violations, we investigate pairing-like correlations in the ground states of ${}^{116}\mathrm{Sn}$, ${}^{106}\mathrm{Sn}$, and ${}^{100}\mathrm{Sn}$. The same effective nucleon-nucleon interaction, namely, the D1S parametrization of the Gogny force, is used to derive both the mean field and correlation components of nuclear wave functions. Calculations are performed using an axially symmetric representation. The structure of correlated wave functions, their convergence with respect to the number of particle-hole excitations, and the influence of correlations on single-particle level spectra and occupation probabilities are analyzed and compared with results obtained with the same two-body effective interaction from BCS, Hartree-Fock-Bogoliubov, and particle number projected after variation BCS approaches. Calculations of nuclear radii and the first theoretical excited $0^{+}$ states are compared with experimental data.

Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, $v_2/\varepsilon$, and the produced entropy fraction, $\Delta \mathcal{S}/{\mathcal{S}}_0$, on the final charged hadron multiplicity density ${\mathit{dN}}_{\mathrm{ch}}/\mathit{dy}$ per unit transverse overlap area $S,(1/S){\mathit{dN}}_{\mathrm{ch}}/\mathit{dy}$. The viscous hydrodynamic simulations are performed with two different versions of the Israel-Stewart kinetic evolution equations, and in each case we investigate the dependence of the physical observables on the kinetic relaxation time. We find approximate scaling of $v_2/\varepsilon$ and $\Delta S/S_0$ with $(1/S){\mathit{dN}}_{\mathrm{ch}}/\mathit{dy}$, with scaling functions that depend on the EOS and, in particular, on the value of the specific shear viscosity $\eta /s$. Small scaling violations are seen even in ideal hydrodynamics, caused by a breaking of the scale invariance of ideal fluid dynamics by the freeze-out condition. Viscous hydrodynamics shows somewhat larger scale-breaking effects that increase with increasing $\eta /s$ and decreasing system size and initial energy density. We propose to use precision studies of these scaling violations to help constrain the shear viscosity $\eta /s$ of the quark-gluon plasma created in relativistic heavy ion collisions.

The ${\mathrm{}}^{13}C(\alpha ,n){\mathrm{}}^{16}O$ reaction constitutes the dominant neutron source for the main $s$ process, which operates at a thermal energy of $\mathit{kT}=8$ keV. Since the cross section at stellar energies is very small, the reaction rate cannot be directly determined and has to be extrapolated from cross section results obtained at higher energies. To remove various discrepancies in the normalization of previous data sets and to subsequently improve the reliability of the extrapolation, we performed measurements of the ${\mathrm{}}^{13}C(\alpha ,n){\mathrm{}}^{16}O$ reaction in the energy range $E_{\mathrm{c}.\mathrm{m}.}=320\text{−}700$ keV. In addition, the double differential scattering cross section ${\mathrm{}}^{13}C(\alpha ,\alpha ){\mathrm{}}^{13}C$ was measured in the energy range $E_{\mathrm{lab}}=2.6\text{−}6.2$ MeV for 28 angles. These data were used to constrain possible contributions from background resonances for a reliable extrapolation with the multichannel $R$-matrix code SAMMY. As a result, the uncertainties were significantly reduced, and a reaction rate of $(4.6\pm 1.0)\times {10}^{-14}$ ${\mathrm{cm}}^3$/moles at $\mathit{kT}=8$ keV ($T=0.1\times {10}^9$ K) was determined.

The structure of high-spin and nonyrast states of the transfermium nucleus ${}^{250}\mathrm{Fm}$ has been studied in detail. The isomeric nature of a two-quasiparticle excitation has been exploited in order to obtain spectroscopic data of exceptional quality. The data allow the configuration of an isomer first discovered over 30 years ago to be deduced, and provide an unambiguous determination of the location of neutron single-particle states in a very heavy nucleus. A comparison to the known two-quasiparticle structure of ${}^{254,252}\mathrm{No}$ confirms the existence of the deformed shell gaps at $N=152$ and $Z=100$.

The matrix coherent-state approach of the interacting boson model with configuration mixing is used to study the geometry of the platinum isotopes. With a parameter set determined in previous studies, it is found that the absolute minimum of the potential for the Pt isotopes evolves from spherical to oblate and finally to prolate shapes when the neutron number decreases from $N=126$ (semi-magic) to $N=104$ (mid-shell). Shape coexistence is found in the isotopes ${}^{182,184,186,188}\mathrm{Pt}$. A phase diagram is constructed that shows the coexistence region as a function of the number of bosons and the strength of the mixing parameter.

Excited states of ${}^{137}\mathrm{Ce}$, populated in the ${}^{130}\mathrm{Te}$(${}^{12}\mathrm{C},5n$) reaction at a beam energy of 65 MeV, have been investigated by $\gamma \gamma$ coincidence spectroscopy using a modest Clover Ge array. Unique spin-parity assignments have been made for most of the levels at high spin and excitation energy by using DCO ratios and polarization information. The known level scheme of ${}^{137}\mathrm{Ce}$ has been considerably revised on the basis of the new information. A sequence of $M1$ transitions, developed on the 5379.1-keV $\frac{33}{2}\hslash$ level has been suggested to be a positive-parity band through unambiguous assignment of multipolarity of 1124.1- and 836.1-keV γ rays. Another positive-parity bandlike structure has been seen, starting at the 2928.4-keV ${\frac{19}{2}}^{+}$ level. Total Routhian surface calculations have been done to predict underlying multi-quasiparticle configurations for the observed bands.

An isomeric state in ${}^{255}\mathrm{Lr}$ with a half-life of $t_{1/2}\hspace{0.5em}=\hspace{0.5em}1.4(1)$ ms and $E_x>720$-keV has been observed for the first time using the GABRIELA setup at the focal plane of the VASSILISSA separator. Based on its $K$-forbiddeness, the configuration of the state is most probably formed by coupling the valence proton to a two quasiparticle neutron excitation. Possible three quasiparticle configurations are discussed.

We study the $\pi N\to \varphi N$ reaction close to the $\varphi N$ threshold within the chiral unitary approach, by combining the ${\pi }^{-}p\to K^{+}{\Sigma }^{-},{\pi }^{-}p\to K^0{\Sigma }^0$, and ${\pi }^{-}p\to K^0\Lambda$ amplitudes with the coupling of ϕ to the $K$ components of the final states of these reactions via quantum loops. We obtain good agreement with experiment when the dominant ${\pi }^{-}p\to K^0\Lambda$ amplitude is constrained with its experimental cross section. We also evaluate the coupling of $N^{*}(1535)$ to $\varphi N$ and find a moderate coupling as a consequence of partial cancellation of the large $\mathit{KY}$ components of $N^{*}(1535)$. We also show that the $N^{*}(1535)$ pole approximation is too small to reproduce the measured cross section for the ${\pi }^{-}N\to \varphi N$ reaction.

We study the properties of neutron stars involving antikaon condensation with three different models in the framework of relativistic mean field (RMF) approximation theory: the Glendenning-Moszkowski (GM) model, the Zimanyi-Moszkowski (ZM) model, and the hybrid derivative coupling (HD) model. We take the isovector-scalar (δ-meson) channel interaction into account in our calculations and find that large mass neutron stars with kaon condensation can exist if the kaon optical potential is appropriately weak. The δ-meson channel interaction has a significant influence on the property of neutron stars and the effects are a little different for the three models.

The stellar ($n,\hspace{0.5em}\gamma$) cross sections of ${}^{79}\mathrm{Br}$, ${}^{81}\mathrm{Br}$, ${}^{85}\mathrm{Rb}$, and ${}^{87}\mathrm{Rb}$ have been determined by a series of ten activation measurements in a quasistellar neutron spectrum corresponding to a thermal energy of $\mathit{kT}\hspace{0.5em}=\hspace{0.5em}25$ keV. The final uncertainties between 3 and 10% were dominated by the γ-ray intensities in the decay of the respective reaction products. All other uncertainties were significantly reduced through variation of the experimental parameters. The consequences of these results for $s$-process nucleosynthesis of Br and Rb, and in particular of the local $s$-only isotopes ${}^{80,\hspace{0.5em}82}\mathrm{Kr}$ and ${}^{86,\hspace{0.5em}87}\mathrm{Sr}$, are discussed with respect to the branching points at ${}^{79}\mathrm{Se}$ and ${}^{85}\mathrm{Kr}$. The contributions of both the main $s$ component from thermally pulsing low mass asymptotic giant branch stars and the weak $s$ component from massive stars are considered in this analysis.

The sub-barrier fusion excitation functions are measured for the first time for the system ${}^7\mathrm{Li}+\hspace{0.5em}{}^{28}\mathrm{Si}$ by the characteristic γ-ray method in the energy range $E_{\mathrm{lab}}=7\text{−}11.5$ MeV. The results show an enhancement, below the barrier, by about a factor of two when compared with the one-dimensional barrier penetration (1D BPM) model. Introduction of coupling with the rotational $2^{+}$ state (1.779 MeV) of the target improves the fit somewhat, but still an enhancement of about 25–40% remains.

Two-nucleon momentum distributions are calculated for the ground states of ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ as a function of the nucleons’ relative and total momenta. We use variational Monte Carlo wave functions derived from a realistic Hamiltonian with two- and three-nucleon potentials. The momentum distribution of $\mathit{pp}$ pairs is found to be much smaller than that of $\mathit{pn}$ pairs for values of the relative momentum in the range 300–500 MeV/$c$ and vanishing total momentum. However, as the total momentum increases to 400 MeV/$c$, the ratio of $\mathit{pp}$ to $\mathit{pn}$ pairs in this relative momentum range grows and approaches the limit 1/2 for ${}^3\mathrm{He}$ and 1/4 for ${}^4\mathrm{He}$, corresponding to the ratio of $\mathit{pp}$ to $\mathit{pn}$ pairs in these nuclei. This behavior should be easily observable in two-nucleon knock-out processes, such as $A(e,e^{\text{'}}\mathit{pN})$.

The neutron-rich Mn isotopes from $A=59$ to 63 have been studied through multi-nucleon transfer reactions by bombarding a ${}^{238}\mathrm{U}$ target with a beam of ${}^{70}\mathrm{Zn}$ at an energy of $E_{\mathrm{lab}}=460$ MeV. Prompt γ rays measured by the CLARA array have been identified unambiguously for each nucleus, using coincidence relationships with ions detected in the high-acceptance magnetic spectrometer PRISMA. The new data extends the knowledge of the low-lying level structure of Mn isotopes, which is discussed in terms of the systematics of the region. Results are compared with large-scale shell-model calculations using different effective interactions and valence spaces.

Semiexclusive measurements of the two-pion-production $p(\alpha ,{\alpha }^{\text{'}})p\pi \pi$ reaction have been carried out at an energy of $E_{\alpha }=4.2$ GeV at the Saturne-II (Saclay) accelerator with the SPES4-π installation. This reaction was investigated by simultaneous registration of the scattered α particle and the secondary proton. The obtained results show that the two-pion production in inelastic α-particle scattering on the proton at the energy of the experiment proceeds mainly through excitation in the target proton of the Roper resonance and its decay with emission of two pions in the isospin $I=0,S$-wave state.

We employ a novel new approach to study local quark-hadron duality using “truncated” moments, or integrals of structure functions over restricted regions of $x$, to determine the degree to which individual resonance regions are dominated by leading twist. Because truncated moments obey the same $Q^2$ evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.

Using recent data we reduce the systematic uncertainty in our measurement [Phys. Rev. C 76, 065803 (2007)] of the excitation energy of the second level above the proton threshold in ${}^{24}\mathrm{Al}$ and find it to be 2523(3) keV, a factor of two improvement over our previously reported value of 2524(6) keV.

The γ decays from an isomeric ${10}^{+}$ state at 6457 keV in the nucleus ${}_{28}^{54}$${\mathrm{Ni}}_{26}$ have been identified using the GSI fragment separator in conjunction with the RISING Ge-detector array. The state is interpreted as the isobaric analog of the 6527-keV ${10}^{+}$ isomer in ${}_{26}^{54}$${\mathrm{Fe}}_{28}$. The results are discussed in terms of isospin-dependent shell-model calculations. Clear evidence is presented for a discrete $\ell =5$ proton decay branch into the first excited $9/2^{-}$ state of the daughter ${}^{53}\mathrm{Co}$. This decay is the first of its kind observed following projectile fragmentation reactions.

We investigate whether isospin mixing can be determined in a model-independent way from the relative strength of $E1$ transitions in mirror nuclei. The specific examples considered are the $A=31$ and $A=35$ mirror pairs, where a serious discrepancy between the strengths of $7/2^{-}\to 5/2^{+}$ transitions in the respective mirror nuclei has been observed. A theoretical analysis of the problem suggests that it ought to be possible to disentangle the isospin mixing in the initial and final states given sufficient information on experimental matrix elements. With this in mind, we obtain a lifetime for the relevant $7/2^{-}$ state in ${}^{31}\mathrm{S}$ using the Doppler-shift attenuation method. We then collate the available information on matrix elements to examine the level of isospin mixing for both $A=31$ and $A=35$ mirror pairs.