To calculate the trajectory of a particle through the system often effective
lengths of the magnets are used which differ slightly from the geometric ones.
In this case the drift lengths used in MOCADI are also not the
geometric ones but effective lengths in order to keep the sum of all lengths
constant. In principle the effective lengths depend on the strength of the
magnetic fields and should be adapted according to the setting of the magnetic
rigidity. In the provided MOCADI input files the effective lengths of the FRS
quadrupoles is about 4cm longer than the geometric length. In case of high field
strength saturation may shorten the effective length by a few centimeters but
the transfer matrix will almost not change. But one should not mix up input
files with geometric lengths and matrices for effective lengths. Otherwise the
overall length will be wrong.
This page was last modified by Dr. Helmut Weick,25th May 2018,