Observations of synchrotron radio noise at the magnetic equator following the high-altitude nuclear explosion of July 9, 1962

This paper describes the results of radio measurements made in Peru of synchrotron radiation at 30 and 50 Mc/s. This radiation was produced by relativistic electrons injected into trapped orbits in the earth's magnetic field during the high-altitude nuclear explosion of July 9, 1962. A preliminary interpretation of these results is also given. At 50 Mc/s there was a brief transient increase in the antenna temperature of 4.5×104°K shortly after the explosion. This can be compared to the normal antenna temperature at that time of 5.5 × 103°K. The excess temperature soon decreased to about 1×104°K and has since decayed only very slowly from this value, the time constant being about two months. From the early transient changes in the antenna temperature, a fairly accurate description of the energy distribution of the electrons is obtained. This spectrum is found to vary almost exactly as the fission spectrum, exp (−0575E - 0.055E2), in the range 1≤E≤5, where E is the kinetic energy in Mev. Above 5 Mev the spectrum falls off somewhat faster than this expression, but the measurements are rather poor in this range. The value 2×1024 is obtained as a rough estimate of the total number of electrons having energies of the order of 1 Mev or greater that were trapped after the explosion.