Magnetospheric particle detection efficiency of a conical telescope

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A semianalytic program has been developed to map the pitch angles of magnetospheric particles onto a detector telescope acceptance cone. The telescope fractional efficiency is defined as the fraction of the pitch angle cone in common with the telescope cone multiplied by the fractional perpendicular component of the exposed detector area, and normalized by 2π. Calculations have been performed as a function of the satellite's location, orbital inclination and the zenith angle of the telescope axis, both in dipole and real geomagnetic field models. At the dipole equator, the peak efficiency occurs at 90° pitch angle. In the real geomagnetic field model, the average value of the pitch angle for maximum efficiency is ∼ 88°. The efficiency function depends strongly upon latitude and is independent of longitude in a dipole field, but depends on longitude in the real field model. In either field model, altitude, angle of tilt and orbital inclination have little effect upon efficiency. The efficiency function calculated at the dipole equator can be used at the minimum magnetic field equator with little error, but not for points away from from the Bmin position. The results are applied to calculate the absolute flux of magnetospheric particles observed near the equator. © 1989.

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Nuclear Inst. and Methods in Physics Research, A

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