Title:

Assessing the Applicability of the Maximum Likelihood Method for LEAP Using COMPTEL Data

The Imaging Compton Telescope (COMPTEL) operated on orbit from 1991 to 2000. COMPTEL was a Compton imaging telescope that operated from 0.75 - 30 MeV. Although the COMPTEL design was not optimized for polarization measurements, it did retain some level of polarization sensitivity. We have analyzed COMPTEL data in search of gamma ray polarization in solar flares and gamma-ray bursts (GRBs). Solar flare candidates were GOES X-ray flares of class C or larger that occurred within the COMPTEL field of view (<30° from the pointing direction). GRB candidates included all those from the BATSE 4B catalog that occurred within the COMPTEL field of view (<30° from the pointing direction). I employed two methods of polarization analysis: the Standard Method which involves binning the azimuthal scattering angles, and the Maximum Likelihood Method (MLM) that does not involve binning and includes energy and Compton scattering angles in its analysis. Krawczynski 2011 reports that under ideal conditions, MLM lowers the minimum detectable polarization (MDP) by ~20% compared to the Standard Method. Our results show that COMPTEL was not sensitive enough to detect polarization using either method. Using simulated data, we demonstrated that the MLM method provides a better method of analysis for the future Large Area Burst Polarimeter (LEAP) mission.

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