Evidence for particle acceleration processes in the magnetotail

Measurements of energetic protons (E> or =50 keV), electrons (E> or =30 keV) ..cap alpha.. particles (E> or =0.64 MeV) and Z> or =3 particles (E> or =2 MeV) in the distant magnetotail by the Energetic Particles Experiment (NOAA Boulder) and the JHU/APL proton-electron telescope on board the IMP 8 satellite for the period November 23-26, 1973, are used to investigate the particle acceleration process in the magnetotail. Evidence is presented that the plasma heating process starts 20--30 min before energetic particle bursts, which suggests that most probably the particle energization in this event takes place in two different phases: (1) up to Eapprox.50 keV in association with the plasma heating process and (2) explosive acceleration in excess of E> or approx. =1 MeV energy.