Enhancement of 0.24‐ to 0.96‐Mev trapped protons during the May 25, 1967, magnetic storm

During the large May 25, 1967, magnetic storm a solid state detector spectrometer aboard the polar‐orbiting satellite OV1‐9 measured 0.24‐ to 0.96‐Mev protons. A nonadiabatic semi‐permanent enhancement of protons was observed following the storm in the region 2.25 < L < 3.25, B = 0.10 ± 0.02, at 1800 LT. The 0.265‐Mev proton flux increased by about a factor of 25, whereas the 0.885‐Mev proton flux increased by a factor of 4–5. This proton increase is much larger than that recently reported by Burns and Krimigis (1972) and is compared with the more common injection‐acceleration of electrons during less severe magnetic storms. From these comparisons we conclude that both the electron and the proton enhancements are selective both in L and in energy. Temporal changes in the energy spectra are consistent with acceleration by means of the E ‐conserving diffusion mode defined by Theodoridis et al. (1969).