No abstract

Particle acceleration and loss in the million electron Volt (MeV) energy range (and above) is the least understood aspect of radiation belt science. In order to measure cleanly and separately both the energetic electron and energetic proton components, there is a need for a carefully designed detector system. The Relativistic Electron-Proton Telescope (REPT) on board the Radiation Belt Storm Probe (RBSP) pair of spacecraft consists of a stack of high-performance silicon solid-state detectors in a telescope configuration, a collimation aperture, and a thick case surrounding the detector stack to shield the sensors from penetrating radiation and bremsstrahlung. The instrument points perpendicular to the spin axis of the spacecraft and measures high-energy electrons (up to ∼20 MeV) with excellent sensitivity and also measures magnetospheric and solar protons to energies well above D.N. Baker ( ) • V.

Particle acceleration and loss in the million electron Volt (MeV) energy range (and above) is the least understood aspect of radiation belt science. In order to measure cleanly and separately both the energetic electron and energetic proton components, there is a need for a carefully designed detector system. The Relativistic Electron-Proton Telescope (REPT) on board the Radiation Belt Storm Probe (RBSP) pair of spacecraft consists of a stack of high-performance silicon solid-state detectors in a telescope configuration, a collimation aperture, and a thick case surrounding the detector stack to shield the sensors from penetrating radiation and bremsstrahlung. The instrument points perpendicular to the spin axis of the spacecraft and measures high-energy electrons (up to ∼20 MeV) with excellent sensitivity and also measures magnetospheric and solar protons to energies well above D.N. Baker ( ) • V.

No abstract

T h e spin-lattice relaxation of paramagnetic ions in ionic crystals takes place via thermal modulations of the complex consisting of the ion and its immediate neighbours. T h e standard theory is that due to Van Vleck, who used a crystal-field model to describe the complex. I n recent years there have been extensive developments in crystal-field techniques, which have removed many of the difficulties. I t has therefore seemed appropriate to attempt to recast the relaxation theory so as to take full advantage of these developments. A t the same time it becomes possible to see more clearly how a molecular-field theory might be formulated. I t is assumed that the reader is reasonably conversant with crystalfield theory, but that he is less likely to be familiar with lattice dynamics. As the only really new feature which needs to be added to crystal-field theory is that of the vibrating lattice, particular attention is paid to this. T h e opportunity is also taken to give a glossary of the jargon used in spin-lattice relaxation theory.