Differential Measurement of Cosmic-Ray Gradient with Respect to Interplanetary Current Sheet

Simultaneous magnetic field and charged particle measurements from the Voyager spacecraft at heliographic latitude separations from 10° to 21 a are used to determine the latitude gradient of the galactic cosmic ray flux with respect to the interplanetary current sheet. By comparing the ratio of cosmic ray flux at Voyager 1 to that at Voyager 2 during periods when both spacecraft are first north and then south of the interplanetary current sheet, we find an estimate of the latitudinal gradient with respect to the current sheet of approximately -0.15 ± 0.05 %/ deg under restricted interplanetary conditions