Next-to-leading-order QCD analyses of the ZEUS data on deep inelastic scattering together with fixed-target data have been performed, from which the gluon and quark densities of the proton and the value of the strong coupling constant ␣ s (M Z ) were extracted. The study includes a full treatment of the experimental systematic uncertainties including point-to-point correlations. The resulting uncertainties in the parton density functions are presented. A combined fit for ␣ s (M Z ) and the gluon and quark densities yields a value for ␣ s (M Z ) in agreement with the world average. The parton density functions derived from ZEUS data alone indicate the importance of HERA data in determining the sea quark and gluon distributions at low x. The limits of applicability of the theoretical formalism have been explored by comparing the fit predictions to ZEUS data at very low Q 2 .

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The production of neutrons carrying at least 20% of the proton beam energy (x L > 0.2) in e + p collisions has been studied with the ZEUS detector at HERA for a wide range of Q 2 , the photon virtuality, from photoproduction to deep inelastic scattering. The neutron-tagged cross section, ep → e ′ Xn, is measured relative to the inclusive cross section, ep → e ′ X, thereby reducing the systematic uncertainties. For x L > 0.3, the rate of neutrons in photoproduction is about half of that measured in hadroproduction, which constitutes a clear breaking of factorisation. There is about a 20% rise in the neutron rate between photoproduction and deep inelastic scattering, which may be attributed to absorptive rescattering in the γp system. or 0.64 < x L < 0.82, the rate of neutrons is almost independent of the Bjorken scaling variable x and Q 2 . However, at lower and higher x L values, there is a clear but weak dependence on these variables, thus demonstrating the breaking of limiting fragmentation. The neutron-tagged structure function, F

A complete set of existing data on hot fusion reactions leading to synthesis of superheavy nuclei of Z =114-118, obtained in a series of experiments in Dubna and later in GSI Darmstadt and LBNL Berkeley, was analyzed in terms of a new angular-momentum dependent version of the fusionby-diffusion (FBD) model with fission barriers and ground-state masses taken from the Warsaw macroscopic-microscopic model (involving non-axial shapes) of Kowal et al. The only empirically adjustable parameter of the model, the injection-point distance (sinj), has been determined individually for all the reactions. Very regular systematics of this parameter have been established. The regularity of the obtained sinj systematics indirectly points at the internal consistency of the whole set of fission barriers used in the calculations. (In an attempt to fit the same set of data by using the alternative theoretical fission barriers of Möller et al. we did not obtain such a consistent result.) Having fitted all the experimental excitation functions for elements Z = 114-118, the FBD model was used to predict cross sections for synthesis of elements Z = 119 and 120. Regarding prospects to produce the new element Z = 119, our calculations prefer the 252 Es( 48 Ca,xn) 300−x 119 reaction, for which the synthesis cross section of about 0.2 pb in 4n channel at Ec.m. ≈ 220 MeV is expected. The most favorable reaction to synthesize the element Z = 120 turns out to be 249 Cf( 50 Ti,xn) 299−x 120, but the predicted cross section for this reaction is only 6 fb (for 3n and 4n channels).

This is a short review of methods and results of calculations of fission barriers and fission halflives of even-even superheavy nuclei. An approvable agreement of the following approaches is shown and discussed: The macroscopic-microscopic approach based on the stratagem of the shell correction to the liquid drop model and a vantage point of microscopic energy density functionals of Skyrme and Gogny type selfconsistently calculated within Hartree-Fock-Bogoliubov method. Mass parameters are calculated in the Hartree-Fock-Bogoliubov cranking approximation. A short part of the paper is devoted to the nuclear fission dynamics. We also discuss the predictive power of Skyrme functionals applied to key properties of the fission path of 266 Hs. It applies the standard techniques of error estimates in the framework of a χ 2 analysis.

Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers B f for 1305 heavy and superheavy nuclei 98 ≤ Z ≤ 126, including even -even, odd -even, evenodd and odd -odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations. We find that the non-axiallity significantly changes first and second fission barrier in many nuclei. The effect of the mass -asymmetry, known to lower the second, very deformed barriers in actinides, in the heaviest nuclei appears at the less deformed saddles in more than 100 nuclei. It happens for those saddles in which the triaxiallity does not play any role, what suggests a decoupling between effects of the mass-asymmetry and triaxiality. We studied also the influence of the pairing interaction strength on the staggering of B f for oddand even-particle numbers. Finally, we provide a comparison of our results with other theoretical fission barrier evaluations and with available experimental estimates.

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A systematic study of global properties of superheavy nuclei in the framework of macroscopic-microscopic method is performed. Equilibrium deformations, masses, quadrupole moments, radii, shell energies, fission barriers and half-lives are calculated using the following macroscopic models: Myers-Swiatecki liquid drop, droplet, Yukawa-plus-exponential, and Lublin-Strasbourg drop. Shell and pairing energies are calculated in Woods-Saxon potential with a universal set of parameters. The analysis covers a wide range of even-even superheavy nuclei from Z=100 to 122. Magic and semimagic numbers occurring in this region are indicated and their influence on the observables is discussed. The strongest shell effects appear at proton number Z=114 and at neutron number N=184. Deformed shell closures are found at N=152 and 162. Spontaneous fission half-lives are calculated in a dynamical approach where the full minimization of the action integral in a three-dimensional deformation space of $\beta$ deformations is performed. The fission half-lives obtained this way are two orders of magnitude smaller than the ones resulting from static calculations. The agreement of theoretical results and experimental data is satisfying