IMAGING GAMMA-RAY SOURCES WITH A COMPTON DOUBLE SCATTER TELESCOPE USING THE EXPECTATION MAXIMIZATION MAXIMUM-LIKELIHOOD (EMML) TECHNIQUE

An Expectation Maximization Maximum Likelihood method (EMML) introduce d by T. J. Hebert [1] has been expanded and used to reconstruct gamma- ray source images. The specific application of this technique to Compt on double scatter data is discussed in this paper. This method shows r eliable results for low event counts such as from weak sources or shor t data acquisition times. Results for simulation and calibration data for fixed and moving sources are presented. The response function of t he detector used and the background subtraction are discussed. The met hod is sensitive to sources with a signal-to-noise ratio of 1%. This m ethod is being used to analyze the 1989 balloon flight data collected by the University of California, Riverside Double Scatter Compton tele scope flown at Fort Summer, New Mexico. Results from the Crab region a re shown.