121958399
Amplitude-exponent relation for the correlation length in the (2+1)-dimensional Ising model
For the critical (2+1)D Ising model defined on a square lattice with antiperiodic boundary conditions, numerical studies suggest relations among the critical exponents and the finite-size scaling amplitudes of correlation lengths similar to those obtained in (1+1) dimensions from conformal invariance.
122107185
A numerical test of the conjectured exact S-matrix of the 2D Ising model in a magnetic field
The finite-size scaling functions of the correlation lengths in the 2D Ising model in a magnetic field are calculated numerically. The asymptotic behaviour in the limit of large scaling variables is studied and can be used to estimate the particle masses and coupling constants of the underlying effective field theory. The results are consistent with the conjectured minimal S-matrix obtained from the conformal bootstrap.
16274257
On the universality of the fluctuation?dissipation ratio in non-equilibrium critical dynamics
The two-time non-equilibrium correlation and response functions in 1D kinetic classical spin systems with non-conserved dynamics and quenched to their zero-temperature critical point are studied. The exact solution of the kinetic Ising model with Glauber dynamics for a wide class of initial states allows for an explicit test of the universality of the non-equilibrium limit fluctuation–dissipation ratio X∞. It is shown that the value of X∞ depends on whether the initial state has finitely many domain walls or not and thus two distinct dynamic universality classes can be identified in this model. Generic 1D kinetic spin systems with non-conserved dynamics fall into the same universality classes as the kinetic Glauber–Ising model provided the dynamics is invariant under the C-symmetry of simultaneous spin and magnetic-field reversal. While C-symmetry is satisfied for magnetic systems, it need not be for lattice gases which may therefore display hitherto unexplored types of non-universal kinetics.
18476524
On the dynamical symmetric algebra of ageing: Lie structure, representations and Appell systems
The study of ageing phenomena leads to the investigation of a maximal parabolic subalgebra of conf_3 which we call alt. We investigate its Lie structure, prove some results concerning its representations and characterize the related Appell systems.
115157615
The exotic conformal Galilei algebra and nonlinear partial differential equations
Abstract The conformal Galilei algebra ( cga ) and the exotic conformal Galilei algebra ( ecga ) are applied to construct partial differential equations (PDEs) and systems of PDEs, which admit these algebras. We show that there are no single second-order PDEs invariant under the cga but systems of PDEs can admit this algebra. Moreover, a wide class of nonlinear PDEs exists, which are conditionally invariant under cga . It is further shown that there are systems of nonlinear PDEs admitting ecga with the realisation obtained very recently in [D. Martelli, Y. Tachikawa, Comments on Galilei conformal field theories and their geometric realisation, preprint, arXiv:0903.5184v2 [hep-th] , 2009]. Moreover, wide classes of nonlinear systems, invariant under two different 10-dimensional subalgebras of ecga are explicitly constructed and an example with possible physical interpretation is presented.
121241561
Finite-lattice extrapolation algorithms
Two algorithms for sequence extrapolation, due to van den Broeck and Schwartz (1979), and Bulirsch and Stoer (1964), are reviewed and critically compared. Applications to three-state and six-state quantum chains and to the (2+1)D Ising model show that the algorithm of Bulirsch and Stoer is superior, in particular if only very few finite-lattice data are available.
122146103
An isotope experiment using Cherenkov range technique
Abstract The ALICE balloon experiment utilizes the Cherenkov-range technique to determine the isotopic composition of the cosmic radiation in the elemental range magnesium through iron. The instrument operates in the energy range 350 MeV/nucleon to 800 MeV/nucleon. Particle charge and energy are determined from scintillation and Cherenkov radiation emissions within light diffusion chambers. Trajectories of incoming particles are determined by means of large area gas drift chambers. The stopping range of the particles is measured in a cellulose nitrate range stack. This paper reports details of the experimental technique and results of the balloon flight.
119994412
A drift chamber telescope for heavy ion track detection
Abstract A drift chamber telescope consisting of six individual drift chambers has been exposed to the heavy ion beam at the Lawrence Berkeley Laboratory, Ca, USA. This is a study for employing drift chambers in a cosmic ray isotope experiment. An amplitude discrimination against δ-rays which accompany the heavy ions is possible. The track detection efficiency for different nuclei is measured and discussed. It is recommended to run the chambers at low sense wire voltage in order to avoid space charge effects. The spatial resolution for Fe nuclei of 518 MeV/nucleon was measured to be σ = 0.3 mm.
122399752
The ALICE instrument and the measured cosmic ray elemental abundances
Abstract A Large Isotopic Composition Experiment (ALICE) is a balloon-borne spectrometer which can determine the elemental and isotopic composition of galactic cosmic rays with energies near 1 GeV/nucleon. ALICE was flown from Prince Albert, Canada in August 1987, and remained at float altitude (120000 feet) for 14.7 hours. In this paper, we describe the experimental methods and analysis which will be used for subsequent isotopic analysis. We obtained very precise charge resolution over the entire designed range: 0.10 and 0.16 charge units at neon and iron, respectively. Results on the galactic cosmic ray abundances and absolute fluxes of the elements from neon through nickel are reported.