Simulation of the interaction of high-energy C60 cluster ions with amorphous targets

Detailed simulations of the interaction of energetic C-60 beams with amorphous targets are presented here. The spatial evolution of the cluster components is calculated accounting for multiple scattering and Coulomb explosion by means of Monte Carlo and molecular dynamics, respectively. The charge states of the individual cluster components (atoms, atomic ions, fragment cluster ions) as a function of penetration depth are also calculated in tandem with the above calculations by means of the Monte Carlo method. The relative importance of scattering versus Coulomb repulsion is studied as a function of the C-60 cluster energy. The effect of the neighboring cluster constituents on the average charge state of the cluster atoms is calculated as a function of the depth of penetration for a C-60 cluster of 40 MeV. The calculation accounts for the increase in ionization energy of the atom due to the other constituents. Relative track radii are calculated as a function of penetration depth and good agreement with the experimental results is obtained for the interaction of a 30 MeV carbon cluster with silicon. Track splitting observed well into the target as measured by Dunlop in yttrium iron garnet is obtained in the simulations described here for the case of amorphous carbon, provided the Coulomb repulsion is screened by the four valence electrons. Collective energy deposition enhancement is calculated for the 720 MeV cluster. Here the cluster constituents are nearly fully ionized, thereby minimizing the ambiguity related to the value of the ionic charge in the calculation

On the Three-dimensional Lattice Model

Using the restricted star-triangle relation, it is shown that the $N$-state spin integrable model on a three-dimensional lattice with spins interacting round each elementary cube of the lattice proposed by Mangazeev, Sergeev and Stroganov is a particular case of the Bazhanov-Baxter model.Comment: 8 pages, latex, 4 figure

Relativistic diffusion

We discuss a relativistic diffusion in the proper time in an approach of Schay and Dudley. We derive (Langevin) stochastic differential equations in various coordinates.We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form.We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution.We discuss drag terms leading to an equilibrium distribution.The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Juettner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.Comment: 9 pages,some numerical factors correcte

Single crystal growth and physical properties of a new uranium compound URhIn5_5

We have grown the new uranium compound URhIn$_5$ with the tetragonal HoCoGa$_5$-type by the In self flux method. In contrast to the nonmagnetic ground state of the isoelectronic analogue URhGa$_5$, URhIn$_5$ is an antiferromagnet with antiferromagnetic transition temperature $T_{\rm N}$ = 98 K. The moderately large electronic specific heat coefficient $\gamma$ = 50 mJ/K$^2$mol demonstrates the contribution of 5$f$ electrons to the conduction band. On the other hand, magnetic susceptibility in the paramagnetic state roughly follows a Curie-Weiss law with a paramagnetic effective moment corresponding to a localized uranium ion. The crossover from localized to itinerant character at low temperature may occur around the characteristic temperature 150 K where the magnetic susceptibility and electrical resistivity show a marked anomaly.Comment: 7 pages, 7 figure

The Complete KLT-Map Between Gravity and Gauge Theories

We present the complete map of any pair of super Yang-Mills theories to supergravity theories as dictated by the KLT relations in four dimensions. Symmetries and the full set of associated vanishing identities are derived. A graphical method is introduced which simplifies counting of states, and helps in identifying the relevant set of symmetries.Comment: 41 pages, 16 figures, published version, typos corrected, references adde

Reconstruction of the Fermi surface in the pseudogap state of cuprates

Reconstruction of the Fermi surface of high-temperature superconducting cuprates in the pseudogap state is analyzed within nearly exactly solvable model of the pseudogap state, induced by short-range order fluctuations of antiferromagnetic (AFM, spin density wave (SDW), or similar charge density wave (CDW)) order parameter, competing with superconductivity. We explicitly demonstrate the evolution from "Fermi arcs" (on the "large" Fermi surface) observed in ARPES experiments at relatively high temperatures (when both the amplitude and phase of density waves fluctuate randomly) towards formation of typical "small" electron and hole "pockets", which are apparently observed in de Haas - van Alfen and Hall resistance oscillation experiments at low temperatures (when only the phase of density waves fluctuate, and correlation length of the short-range order is large enough). A qualitative criterion for quantum oscillations in high magnetic fields to be observable in the pseudogap state is formulated in terms of cyclotron frequency, correlation length of fluctuations and Fermi velocity.Comment: 4 pages, 3 figure

Alpha-induced reactions for the astrophysical p-process: the case of 151Eu

The cross sections of 151Eu(alpha,gamma)155Tb and 151Eu(alpha,n)154Tb reactions have been measured with the activation method. Some aspects of the measurement are presented here to illustrate the requirements of experimental techniques needed to obtain nuclear data for the astrophysical p-process nucleosynthesis. Preliminary cross section results are also presented and compared with the predictions of statistical model calculations.Comment: Accepted for publication in Journal of Physics Conference Series, proceeding of the Nuclear Physics in Astrophysics IV. conferenc