differential particle flux

The differential particle directional flux j(E,w) denotes the number of particles of energy E per unit energy interval, per unit area, per unit time, per unit solid angle of observation, passing through an area perpendicular to the viewing direction.  The angle w is the angle between the viewing direction and the local magnetic field. It is approximately obtained from the count rate of a physical detector measuring the flux of particles between energy E and E + dE, geometric factor G, and solid angle of view dW through the relationship  j(E,w) = C/(G x dE x dW x dt) where C is the number of detector counts in time dt.