Track reconstruction and momentum measurement

The reconstruction of a charged particle’s trajectory in a magnetic field allows us to determine the momentum vector, that is both the particle’s momentum and its direction. This chapter begins with the description of typical magnetic field configurations and the parametrisation of particle trajectories in homogeneous magnetic fields. For different detector configurations a detailed discussion of the reconstruction of particle trajectories from the measured points. Special attention is given to the achievable resolutions of position, direction, momentum and impact parameter, including newly derived formulas for the effects of multiple scattering.