Research Associate Professor
Cosmic Ray Physics
Joint Appointment Physics Department
University of Chicago
I received my Ph.D. from the University of Chicago in 1982, after completing my undergraduate studies at Swarthmore College. I, and two other scientists, moved from the University of Chicago to the University of New Hampshire in October 2002.
My research involves studies of heliospheric energetic particles in the 1-10,000 MeV energy range. The sources of these particles are: cosmic rays, anomalous components, solar particle events and planetary magnetospheres. Cosmic rays are fully stripped atoms permeating the galaxy, and are thought to be accelerated (for the most part) by shocks associated with supernovae remnants. Anomalous components are neutral atoms in the local interstellar medium which penetrate the heliosphere, become ionized (usually singly) through charge exchange with the solar wind or UV photoionization, in the inner heliosphere, are picked up by the solar wind and then reaccelerated at the solar wind termination shock (at ~100 AU from the Sun). Solar energetic particles are charged particles accelerated either in the lower corona and associated with solar flares or accelerated at traveling shocks driven by coronal mass ejections emitted from the Sun (also often associated with solar flares). The largest source of heliospheric particles coming from planetary magnetospheres are electrons accelerated in the radiation belts of Jupiter which escape into interplanetary space.
My studies include looking at temporal and spatial variations of these charged particles, their energy and momentum spectra, elemental and isotopic composition and inferred charge state distributions. These studies often require magnetic field and plasma data which are usually supplied by investigators using other experiments on the spacecraft.
My research also involves the development of detectors and associated technologies used to detect these particles with instruments on space based platforms, the commanding of these instruments while in space, the development of software to analyze the data, and the interpretation of this data. In all these efforts I am usually one of a team of scientists working to achieve our goals. I have been involved with investigations using instruments on the Pioneer-10 and Pioneer-11 deep space probes - which traveled to 3 times the distance of Pluto; the Ulysses International Solar-Polar Mission (ISPM) - the only man-made device to orbit the Sun perpendicular to the plane of the ecliptic; the Interplanetary Monitoring Platforms, IMP-7 and IMP-8 - high-Earth orbiters; and the Combined Release and Radiation Effects Satellite (CRRES) - a low-Earth orbiter. I am also the principal investigator for the Climax and Haleakala neutron monitors - ground based cosmic ray detectors. In addition to existing experiments I am involved in the development of new technologies to make extremely light-weight, low-mass, low-power charged particle instruments for spacecraft use. Also I am part of a team designing new instruments to study positrons and neutrons in space.