Global peak flux profile of proton precipitation in the equatorial zone

Abstract

Particle precipitation near the equator within ±30° geomagnetic latitude was investigated by the Phoenix-1 instrumentation on board the S81-1 mission. The monitor telescope on board the mission was sensitive to protons in the energy range 0.6-91 MeV, to alpha particles in the energy range 0.4-80 MeV/nucleon and <i>Z</i> <img src='http://www.niscair.res.in/jinfo/greaterequal.gif' border=0>3 particles (¹²C) of energy greater than 0.7 MeV/nucleon. The peak efficiency of the telescope was for particles of ~ 88° pitch angles at the line of minimum magnetic field. Careful separation of the magnetically quiet time equatorial particle data from global data coverage and subsequent analysis shows that the ML detector on board the mission detected mostly protons. The proton peak flux profile follows the line of minimum magnetic field. The full width at half maximum (FWHM) of the equatorial zone is ~ 13°, which is well within the EUV emission zone.