Both Caltech and Non-Caltech students will be considered

Project Title:

Computer Modeling of Idealized Discrete Scatting Structures

Project Description:

This SURF task principally involves computer modeling of idealized discrete scattering structures in the tropospheric, interlanetary and interstellar media. The goal is to see the extent to which simple models of refractive "lenses" in the troposhere/IPM/ISM can reproduce measurements of extreme scattering events (ESEs) observed in spacecraft Doppler tracking data, pulsar flux and timing data, and light curves of quasi-stellar objecs (QSOs). A secondary task, if time permits, will be analyzing spacecraft Doppler data to identify candidate ESEs.

Background Information:

A radio signal propagating through an irregular medium is scatered and develops amplitude and phase variations. If the medium has a hierarchy of irregularity scales the description is in terms of the power spectrum of the irregularities. If there are large discrete scatterers in addition to the background continuum, then extreme scattering events (ESEs) are observed. ESEs have been observed in the ISM (pulsar and QSO observations) and events that may be related have been observed in the earth's troposphere and possibly the IPM. In addition to their intrinsic interest, these scattering events complicate searches for burst radiation in very-low-frequency (ISM distortion of pulsar times-of-arrival) and low-frequency gravitational wave searches (tropospheric/ISM scattering in spacecraft Doppler searches).

Literature references or articles that may provide more information on the project:

Cognard et al. "An Extreme Scattering Event in the Direction of the Millisecond Pulsar 1937+21" Nature, 366, 320 (1993)
Fiedler et al. "A Summary of Extreme Scattering Events and a Descriptive Model" Ap. J. 430, 581 (1994)

Requirements (skills, specific coursework, academic major, year in school, etc.):

The student should be at the junior/senior leven majoring in physics or engineering, know FORTRAN, be familiar with UNIX, have coursework in computational physics, and have some familiarity with linear transforms. Some exposure to optics would be useful.

Research Sponsor Name: John Armstrong
E-Mail: john@oberon.jpl.nasa.gov
Division: JPL
Telephone: (818) 394-3151
Address: M/C 238-725

For further information, contact Dr. Armstrong

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