University of New Hampshire University of New Hampshire Scholars' Repository Doctoral Dissertations Student Scholarship Spring 1987 GAMMA-RAY IMAGING OBSERVATIONS OF THE CRAB AND CYGNUS REGIONS MARK LEWIS MCCONNELL University of New Hampshire, Durham Follow this and additional works at: https://scholars.unh.edu/dissertation Recommended Citation MCCONNELL, MARK LEWIS, "GAMMA-RAY IMAGING OBSERVATIONS OF THE CRAB AND CYGNUS REGIONS" (1987). Doctoral Dissertations. 1512. https://scholars.unh.edu/dissertation/1512 This Dissertation is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. 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Other _______________________________________________________________________ University Microfilms International G a m m a -R a y I m a g in g O bservations o f THE C r a b a n d C y g n u s R e g io n s BY MARK LEWIS McCONNELL B.S., Case Western Reserve University, 1980 A DISSERTATION Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Physics May, 1987 This dissertation has been examined and approved. Edward L. Chupp, Dissertation Professor of Physics Roger L. Amoldy Professor of Physics Lennard A. Fisk, Jr. Professor of Physics David J. Forrest/ Research Associate Professor of Physics Jocnen Heisenberg ^ Professor of Physics Edward E. Fenimore Los Alamos National Laboratory a.)3,Q I gT Date This dissertation is dedicated to the three most important people in my life - my wife, Chris, and my parents, Peggy and Burt. Without their love and support, this work might never have been completed. Acknowledgements I would like to thank my advisor, E. L. Chupp, for providing the opportunity to participate in this research program. Dave Forrest has provided valuable guidance, inspiration and support throughout the entire project. The continuing support of Phil Dunphy and Jon Googins made possible the successful development and operation of the DGT instrument. During the later stages of this work, the contributions of Alan Owens have been especially useful. Discussions with Tom Vestrand have been useful in elucidating some of the theoretical issues raised during the course of this research. In addition to those named above, there are numerous persons who have made contributions, both large and small, over the past seven years. Included among these are Dipen Bhattachaiya, Indulis Gleske, Mttgens Lauritzen, and Mark Popecki. The drafting work contained in this dissertation was provided by Sherry Palmer. Hank Dolben of the UNH Magnetosphere Research Lab kindly provided access to an Apple LaserWriter on which this dissertation was printed. Finally, the support of Albert G. Opp and the National Aeronautics and Space Administration (under NASA grant NGL30-002-021) is gratefully acknowledged. Publication List McConnell, M. L., Forrest, D. J., Chupp, E. L., and Dunphy, P. P. 1982, IEEE Trans. Nucl. Sci., 29,155. "A Coded Aperture Gamma-Ray Telescope." McConnell, M. L., Dunphy, P. P., Forrest, D. J., and Chupp, E. L. 1983, in Adv. Space Res., 3,105. "A Directional Gamma-Ray Telescope Using Coded Aperture Techniques." McConnell, M. L., Dunphy, P. P, Forrest, D. J., Chupp, E. L., and Owens, A. 1987, to be published in Ap. J. "Gamma-Ray Observations of the Crab Region Using a Coded Aperture Telescope." McConnell, M. L., Chupp, E. L., Dunphy, P. P., Forrest, D. J., and Owens, A. 1987, to be submitted to Ap. J. "Gamma-Ray Observations of the Cygnus Region with a Coded Aperture Telescope - Detection of MeV radiation from Cyg X-1." Dunphy, P. P., McConnell, M. L., Chupp, E. L., Forrest, D. J., and Owens, A. 1987, to be submitted to Nucl. Instr. Methods. "A Balloon Borne Coded Aperture Telescope for Low-Energy Gamma-Ray Astronomy." v TABLE OF CONTENTS DEDICATION........................................................................................................... iii ACKNOWLEDGEMENTS....................................................................................... iv PUBLICATION LIST............................................................................................... v LIST OF TABLES..................................................................................................... ix LIST OF FIGURES.................................................................................................. x ABSTRACT.......................................................................................... xv CHAPTER PAGE INTRODUCTION..................................................................................................... 1 I. SCIENTIFIC BACKGROUND ................................................................. 8 Crab Nebula/Pulsar ......................................................................... 8 Basic Theory ............................................................................. 9 Gamma Ray Continuum Measurements .................................... 19 Gamma-Ray Line Emission ....................................................... 21 CygnusX-1 ....................................... 22 Basic Theory .......................................................................... 22 Luminosity Variations ...................................................... 33 Spectral Observations ................................................................ 35 Other Sources .................................................................................. 36 A0535+26................................................................................. 36 Anticenter Diffuse Emission ..................................................... 37 Cygnus X-3 .............................................................................. 38 vi II. INSTRUMENTATION .......................................................................... 40 Coded Aperture Imaging ................................................................. 40 Basic Concepts of Coded Aperture Imaging .............................. 42 Imaging Statistics ...................................................................... 46 Background Systematics ........................................................... 47 Partial Mask Coding ................................................................. 55 The Directional Gamma-Ray Telescope ........................................... 56 The Detector Array and Associated Electronics .......................... 56 The Coded Mask ....................................................................... 63 Gondola and Pointing System. ................................................. 65 Telemetry and Ground Station ............................. 67 Instrumental Background ......................................................... 68 Sensitivity to Celestial Sources .................................................. 72 III. OBSERVATIONS .................................................................................