Physical Processes Commons^™

Experimental Stark Shift Of Several Nii And Oii Spectral Lines, Mara Scepanovic, Vladimir Milosavljevic, Stevan Djenize, Mihajlo Platisa, Jaroslav Labat

Articles

Stark shift of four NII and seven OII spectral lines have been measured for the first time in the linear low pressure pulsed arc plasma and compared with existing theoretical values.

Relativistic Particle Transport In Hot Accretion Disks, P. A. Becker, Menas Kafatos, M. Maisack

Mathematics, Physics, and Computer Science Faculty Articles and Research

Accretion disks around rapidly rotating black holes provide one of the few plausible models for the production of intense radiation in AGNs above energies of several hundred MeV. The rapid rotation of the hole increases the binding energy per nucleon in the last stable orbit relative to the Schwarzschild case, and naturally leads to ion temperatures in the range 10^12-10^13 K for sub-Eddington accretion rates. The protons in the hot inner region of a steady, two-temperature disk form a reservoir of energy that is sufficient to power the observed EGRET outbursts if the black hole mass is 10^10 M0 • …

Transonic Inviscid Disc Flows In The Schwarzschild Metric – I, Menas Kafatos, Ruixin Yang

Mathematics, Physics, and Computer Science Faculty Articles and Research

The coupled hydrodynamic equations governing equatorial flows applicable to inviscid disc accretion in the Schwarzschild metric are solved analytically and numerically. Here, we concentrate on the transonic solutions, that represent physically allowed accretion on to black holes. A polytropic equation linking gas pressure and density is assumed, and solutions are obtained for different conditions, such as isothermal and adiabatic gas flows. The dependence of those solutions on the angular momentum is explored. Under certain conditions, when there exist multiple possible sonic points, the numerical simulation automatically zeros in to the unique transonic solution passing through one of the sonic points.

Time Projection Chamber's Efficiency, Obtained Using Cern's Geant Code, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

Geometrical acceptance and reconstruction of tracks have been carried out for a Time Projection Chamber (TPC) used in Experiment NA35: the 35th experiment in the North Area of the Super Proton Synchrotron (SPS), located at the European Organization for Nuclear Research (CERN). NA35 used the SPS at CERN to produce 6.4 TeV beams of 32S for central collisions with Au nuclei. The TPC modeling effort used a modified version of CERN's Monte Carlo program GEANT, which simulates the response of the NA35 TPC to output from CERN's primary event generators. GEANT was used to simulate three-dimensional pixel data in the …

Monte Carlo Director Modeling And Display, Using The Cern Laboratory, Christine A. Byrd, Charles M. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

Detectors for high energy nuclear physics experiments are being modeled using programs developed and maintained at CERN, the European Organization for Nuclear Research. These programs include data handling and display routines, as well as those using random-sampling Monte Carlo techniques to calculate energy depositions for high energy particles as they pass through the various parts of the detector system. The complete CERN library has been imported for use with our Workstation computers in a multiple user environment. The enormous CERN Monte Carlo program GEANT(French for GIANT) tracks the progress of a particle through a detector on a simulated event-by-event basis. …

A Space-Based Solar Screen Against Climatic Warming, Michael Noah Mautner

Chemistry Publications

The expected global warming may be reversed by space-based screen that would intercept a fraction of the solar radiation incident on Earth. Warming by 2-5^oC could be prevented by intercepting 3-7%, respectively, of the incident solar radiation. The screen may be constructed for example of a thin film, a grid of film supported by a mesh or fine-grained dust deployed in orbit about the Earth. For an average film thickness or particle radius of 0.001 cm, the required mass is 10¹⁴ - 10¹⁵ g, equivalent to a medium sized lunar mountain or asteroid. The material may …

The Orbital Period Of The Optical/X-Ray Burster X1735-444 (V926 Sco), R. H. D. Corbet, J. R. Thorstensen, P. A. Charles, J. W. Menzies

Dartmouth Scholarship

We present extensive CCD photometry of the optical counterpart of X1735–444 which reveals the orbital period of the system. It is periodically variable with a period of 4.654 hr and a full amplitude of 0.15 mag. The mean modulation is quasi-sinusoidal; there are, however, also significant intrinsic deviations from the mean light curve.

Spectroscopic Studies Of 4u1735 – 44; Evidence For Binary Motion, A. P. Smale, P. A. Charles, I. R. Tuohy, J. R. Thorstensen

Dartmouth Scholarship

We have obtained optical spectroscopy of the X-ray burst source 4U1735 – 44 with spectral resolution of ∼ 1.6 Å and a time resolution of ∼ 30 min. There is strong evidence for cyclic He II velocity variations, but we are unable to confirm or deny either of the previously reported possible binary periodicities in the source. However, kinematic arguments suggest that the companion can be classified as being of spectral type F0–K5 V and the presence of the Ca II K interstellar absorption line at λ 3933 leads to a lower limit on the distance of the source of …

Range Evaluation Using Aerial Photography, D G. Wilcox

Journal of the Department of Agriculture, Western Australia, Series 4

The Department of Agriculture, in association with the University of Western Australia, recently undertook a study of the application of aerial photography to range condition monitoring in three rangeland types in the mulga zone of Western Australia.

The project was financed by the Rural Credits Development Fund and the C.S.l.R.O. Rangelands Research Unit.

This article deals in a general way with the possible use of aerial photography in rangeland administration.

Comets And Meteors, Lincoln N. Oatley

Student and Lippitt Prize Essays

Defines and describes named comets and meteor events and their scientific study.