Ph.D. Dissertation (1987) : Gamma-Ray Imaging Observations of the Crab and Cygnus Regions

Research Interests

High Energy Astrophysics

High energy astrophysics (X-ray, gamma-ray and cosmic ray astronomy) offers an insight into some of the most energetic processes that take place in the universe. Through the development and use of a series of balloon-borne and space-borne experiments, my research, in collaboration with colleagues at UNH and at various institutions in the U.S. and in Europe, attempts to explore some of these phenomena. Most of my research concentrates on studies of celestial X-ray and gamma-ray emissions. For the past 15 years I have concentrated on the analysis of the data being returned from the Compton Telescope experiment (COMPTEL) on NASA's Compton Gamma-Ray Observatory (CGRO). Although CGRO was de-orbited by NASA in June of 2000, we continue to study the extensive set of data returned by COMPTEL from over nine years of on-orbit operations. I am especially interested in the study of the accretion of matter onto compact objects (such as neutron stars and black holes). In addition, we are continuing our studies of energetic solar emissions that were observed by CGRO. We are also using data from COMPTEL to study atmopsheric neutrons, which can play a role in electronics reliability and atmospheric chemistry.

I am using data from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), to study the polarization of hard X-ray emission from solar flares. This should provide information on the geometry of the particle acceleration process and shed some light on the precise nature of the acceleration mechanism. By studying such nearby particle acceleration processes, we hope to gain new insights into the more distant (and more energetic) acceleration processes in the universe.

I am also active in several other projects that involve the development new detector technologies. For example, I am actively working on the development of new instrumentation for studying hard X-ray polarization from both solar flares and gamma-ray bursts. We are developing new solid state (CdZnTe) gamma-ray detectors that could be used in a variety of astrophysical applications, including both hard X-ray coded-aperture imaging detectors and a new generation of Compton telescopes. We have also successfully demonstrated a new type of neutron telescope that will be used for studying solar flare emissions.

Several of these technologies may also have more practical applications. Our solid state gamma-ray detectors, for example, might be useful in several types of medical imaging applications. Our neutron telescope promises to be a useful tool for studying atmospheric radiations that adversely impact computers and other electrical equipment, particularly at high altitudes. It might also be useful as a monitor for nuclear waste management. As part of our research, we are exploring these other areas where our newly-developed technology may prove valuable.

Last Updated: Sun, Oct 19, 2003