A laboratory scale model for the investigation of cosmic ray threshold rigidities

Abstract

A technique is described for the study of the geomagnetic threshold rigidities by means of a laboratory scale model in which the motion of the cosmic ray particles in the earth's magnetic field is simulated by that of a beam of electrons moving in the magnetic field of a terrella, scaled so as to represent the geomagnetic field. Störmer and main cone threshold rigidities have been detected by this technique both for the dipole representation of the geomagnetic field and for a field including non-dipole terms roughly similar, in magnitude, to those occurring in the earth's field. The modifications to the Störmer threshold rigidities, calculated by the Quenby-Webber method for the terrella field, have been checked and a preliminary investigation of the effect on the threshold rigidities of uniform external fields has been carried out.