Galactic Cosmic Rays from Supernova Remnants: II Shock Acceleration of Gas and Dust

This is the second paper (the first was astro-ph/9704267) of a series analysing the Galactic Cosmic Ray (GCR) composition and origin. In this we present a quantitative model of GCR origin and acceleration based on the acceleration of a mixture of interstellar and/or circumstellar gas and dust by supernova remnant blast waves. We present results from a nonlinear shock model which includes (i) the direct acceleration of interstellar gas-phase ions, (ii) a simplified model for the direct acceleration of weakly charged dust grains to energies of order 100keV/amu simultaneously with the gas ions, (iii) frictional energy losses of the grains colliding with the gas, (iv) sputtering of ions of refractory elements from the accelerated grains and (v) the further shock acceleration of the sputtered ions to cosmic ray energies. The calculated GCR composition and spectra are in good agreement with observations.Comment: to appear in ApJ, 51 pages, LaTeX with AAS macros, 9 postscript figures, also available from ftp://wonka.physics.ncsu.edu/pub/elliso

Degenerate Variational Integrators for Magnetic Field Line Flow and Guiding Center Trajectories

Symplectic integrators offer many advantages for the numerical solution of Hamiltonian differential equations, including bounded energy error and the preservation of invariant sets. Two of the central Hamiltonian systems encountered in plasma physics --- the flow of magnetic field lines and the guiding center motion of magnetized charged particles --- resist symplectic integration by conventional means because the dynamics are most naturally formulated in non-canonical coordinates, i.e., coordinates lacking the familiar $(q, p)$ partitioning. Recent efforts made progress toward non-canonical symplectic integration of these systems by appealing to the variational integration framework; however, those integrators were multistep methods and later found to be numerically unstable due to parasitic mode instabilities. This work eliminates the multistep character and, therefore, the parasitic mode instabilities via an adaptation of the variational integration formalism that we deem ``degenerate variational integration''. Both the magnetic field line and guiding center Lagrangians are degenerate in the sense that their resultant Euler-Lagrange equations are systems of first-order ODEs. We show that retaining the same degree of degeneracy when constructing a discrete Lagrangian yields one-step variational integrators preserving a non-canonical symplectic structure on the original Hamiltonian phase space. The advantages of the new algorithms are demonstrated via numerical examples, demonstrating superior stability compared to existing variational integrators for these systems and superior qualitative behavior compared to non-conservative algorithms

An Arabic Version of the Spiritual Well-Being Scale

This article reports on two studies to develop and validate an Arabic language version of the Spiritual Well-Being Scale (SWBS). The first study was a pilot study at a major government university in Jordan (N = 75, students). The second and main study was conducted in 5 large regional hospitals in Jordan (N = 63, patients). The SWBS was translated from English to Arabic and reviewed by an expert panel for language, cultural, and spiritual consistency. The Arabic version of the SWBS was revised after the results of the pilot study and further reviewed by an expert panel. The resulting data were subjected to descriptive and factor analysis. Results showed that the final version of the SWBS used in the main study had a two-factor structure consistent with previous studies. Descriptive data for a range of demographic variables are presented. Issues of inadequate translation and lack of variation in responses for some items are identified and the results discussed in light of dominant Islamic theological frameworks. © 2012 Taylor and Francis Group, LLC

Measurement of the Equilibrium Emittance of an Electron-Cooled 45 MeV Proton Beam

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

KECK HIRES Spectroscopy of APM 08279+5255

With an optical R-band magnitude of 15.2, the recently discovered z=3.911 BAL quasar APM 08279+5255 is an exceptionally bright high redshift source. Its brightness has allowed us to acquire a high signal-to-noise ratio (~100), high resolution (~6 km/s) spectrum using the HIRES echelle spectrograph on the 10-m Keck I telescope. Given the quality of the data, these observations provide an unprecedented view of associated and intervening absorption systems. Here we announce the availability of this spectrum to the general astronomical community and present a brief analysis of some of its main features.Comment: 21 pages including 5 figures. Accepted for publication by PAS

Acceleration of Solar Wind Ions by Nearby Interplanetary Shocks: Comparison of Monte Carlo Simulations with Ulysses Observations

The most stringent test of theoretical models of the first-order Fermi mechanism at collisionless astrophysical shocks is a comparison of the theoretical predictions with observational data on particle populations. Such comparisons have yielded good agreement between observations at the quasi-parallel portion of the Earth's bow shock and three theoretical approaches, including Monte Carlo kinetic simulations. This paper extends such model testing to the realm of oblique interplanetary shocks: here observations of proton and alpha particle distributions made by the SWICS ion mass spectrometer on Ulysses at nearby interplanetary shocks are compared with test particle Monte Carlo simulation predictions of accelerated populations. The plasma parameters used in the simulation are obtained from measurements of solar wind particles and the magnetic field upstream of individual shocks. Good agreement between downstream spectral measurements and the simulation predictions are obtained for two shocks by allowing the the ratio of the mean-free scattering length to the ionic gyroradius, to vary in an optimization of the fit to the data. Generally small values of this ratio are obtained, corresponding to the case of strong scattering. The acceleration process appears to be roughly independent of the mass or charge of the species.Comment: 26 pages, 6 figures, AASTeX format, to appear in the Astrophysical Journal, February 20, 199