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) introduced by T.J. Hebert has been expanded and used to reconstruct gamma-ray source images. The specific application of this technique to Compton double scatter data is discussed in this paper. This method shows reliable results for low event counts such as from weak sources or short data acquisition times. Results for simulation and calibration data for fixed and moving sources are presented. The response function of the detector used and the background subtraction are discussed. The method is sensitive to sources with a signal-to-noise ratio of 1%. This method is being used to analyze the 1989 balloon flight data collected by the University of California, Riverside Double Scatter Compton telescope flown at Fort Sumner, New Mexico. Results from the Crab region are shown.< >