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in creator/contributor: "Gisler, G.R."

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Composition and energetics of solar flare particle events measured by satellites, 1989--1991

The Synchronous Orbit Particle Analyzer (SOPA), on board the satellite 1989-046 and others, has detected ions from carbon through nickel at energies from 2 to 50 MeV in the great solar energetic particle events of the current solar cycle. Energetic protons from the same events have been detected by the Charged Particle Analyzer (CPA) on board the satellite 1984-129 and others. We present here a collection of data from these various instruments that includes events of 1989, 1990, and 1991. We de… more

Date: January 1, 1991

Creator: Gisler, G.R.; Belian, R.D.; Cayton, T.E. & Reeves, G.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Inclusion of photon production and transport and (e/sup +/e/sup /minus//) pair production in a particle-in-cell code for astrophysical applications

This present study constitutes the first attempt to include, in a particle-in-cell code, the effects of radiation losses, photon production and transport, and charged-particle production by photons scattering in an intense background magnetic field. We discuss the physics and numerical issues that had to be addressed in including these effects in the ISIS code. Then we present a test simulation of the propagation of a pulse of high-energy photons across an intense magnetic field using this modi… more

Date: January 1, 1989

Creator: Sulkanen, M.E. & Gisler, G.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

PHERMEX as an injector to a modified betatron

The PHERMEX accelerator is a pulsed three-cavity, 50-MHz, standing-wave rf linear accelerator. It is used to produce a 30-MeV, 200-ns envelope of electrons for flash radiography and electron beam experiments. The 200-ns electron pulse contains 10 micropulses. The FWHM of a single micropulse is 3.3 ns. Peak micropulse current varies from 350 to 850 A with widths of 3 and 5 ns, respectively. We propose to inject this beam into a solenoidal field with a neutralizing background gas and stack the PH… more

Date: January 1, 1985

Creator: Moir, D.C. & Gisler, G.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Simulations of second-order Fermi acceleration of electrons: Solving the injection problem

The boosting of electrons from a Maxwellian distribution into a suprathermal power-law tail has long been recognized as an important bottleneck governing the subsequent acceleration of some of these electrons to relativistic energies. This is the seed or injection problem. I study this boosting process using a test-particle simulation code, following the full equations of motion of tens of thousands of electrons chosen from a thermal population as they move through general time-dependent magnet… more

Date: January 1, 1991

Creator: Gisler, G.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Space optical and low-frequency radio searches for earth-crossing asteroids and comets

Earth-crossing asteroids (ECAs) are small and backscatter strongly, so they are usually discovered near opposition during dose approaches to Earth. This opposition effect produces strong biases in Earth-based searches for ECAS, particularly for Atens. An observing site much closer to the sun than the orbit of Earth, such as a satellite orbiting Venus or telescopes on Mercury, would not suffer this bias. All Atens that cross the orbit of Earth would be observable near opposition from these sites… more

Date: January 1, 1993

Creator: Hills, J.G. & Gisler, G.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Spatio-spectral image analysis using classical and neural algorithms

Remote imaging at high spatial resolution has a number of environmental, industrial, and military applications. Analysis of high-resolution multi-spectral images usually involves either spectral analysis of single pixels in a multi- or hyper-spectral image or spatial analysis of multi-pixels in a panchromatic or monochromatic image. Although insufficient for some pattern recognition applications individually, the combination of spatial and spectral analytical techniques may allow the identifica… more

Date: December 31, 1996

Creator: Roberts, S.; Gisler, G.R. & Theiler, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department