Channelling and channelling radiation
The study of channelling phenomena has developed rapidly since the early 1960s and today channelling has found many applications. The radiation emitted by channelled megaelectronvolt and gigaelectronvolt electrons and positrons has been investigated extensively and the possibility of, for example, constructing intense tunable X- and γ-ray sources is being explored. Multi-gigaelectronvolt radiation and pair-creation processes in single crystals show similarities with strong-field effects and are of particular interest because of high production rates that persist far beyond the channelling regime.
The transition from order to chaos in atomic nuclei has been studied analytically and numerically using a quadrupole-quadrupole residual interaction. This interaction leads to chaotic behaviour, but the critical energyEC≅12.6 MeV, corresponding to the onset of chaos, is higher than that of the experimental one.