Introduction

The FTK energy fitter is a maximum likelihood energy fitter that uses all the light in an event to estimate the energy of events in SNO. The basic premise of FTK is to estimate the number of direct photons, Rayleigh scattered photons, photons reflecting off the PMTs or AV and PMT noise hits. The estimated number of hits is compared to the number of observed hits in the event to determine the energy.

A detailed explanation of FTK's inner working has been posted on Manhattan.