On the azimuthal drift of substorm-injected protons

The longitude and time dependence of the pitch angle distribution function of protons injected during substorms on a given L shell is studied. The results are compared with the experimental data of Konradi et al. (1973). The theoretical importance of the anisotropy of the initial distribution function and of the longitudinal width of the injection region is stressed. It is suggested that measurements be made at low pitch angles (< or =20degree)