FAST RUNGE-KUTTA METHOD FOR FITTING TRACKS IN A MAGNETIC-FIELD

Efficient methods for fitting tracks of charged particles in magnetic fields need derivatives of track coordinates with respect to the parameters defining the track. The problem of computing derivatives analytically is solved for a particular Runge-Kutta integration method. This Runge-Kutta fitting method is being used in the off-line analysis of a CERN SPS experiment, where it was developed as an alternative to the quintic spline method. It converges faster than the quintic spline, and is quite comparable with respect to computer speed and precision. © 1979.