Dr. Simon Blyth working at both Daya Bay and JUNO performed a significant step forward  developing a dedicate software package Opticks which performs an optical photon simulation with help of  NVIDIA GPU Technology. A great movie showing almost real time simulation can be found at this link.

A presentation of Dr. Simon Blyth at forthcoming NVIDIA GPU Technology Conference on Wednesday April 6th http://www.gputechconf.com can be found here