The Monte Carlo track rotation estimator

A new formulation of the Monte Carlo approach to particle transport problems is described by defining a direct point flux estimator which extracts information from ''passage'' points rather than ''collision'' points. The approach leads directly to the radical new concept of track rotation and provides a statistical framework in which it is possible to prove the validity of the track rotation concept in spherically symmetric configurations and the validity of the compensated track rotation concept in non-spherically symmetric configurations. The approach can lead to essentially infinite gains in efficiency over conventional analog Monte Carlo methods which cannot directly estimate the flux at a point. (B.G.)