Soft particle flux above 130 km at midlatitude

Abstract

Measurements have been made from latitudes 22°N and 17°N with rocket-borne, thin-window proportional counters of a variable flux of low-energy particles (electron energy greater than 3 kev) approaching the earth from the southern half of the sky. These particles were detected on three separate rocket flights at altitudes above 120 km and at an L value of approximately 1.1. The three measurements differ in intensity but are very similar in spectral shape, with approximately an E−1 dependence. A typical flux value is 100 particles/cm² kev sec ster at an energy of 4 kev. These particles are of particular importance in low-energy X-ray astronomy experiments where they may be the dominant source of background in certain regions of the sky.