Measurement of highly transient electrical charging following high-intensity laser-solid interaction

The multi-million-electron-volt proton beams accelerated during high-intensity laser-solid interactions have been used as a particle probe to investigate the electric charging of microscopic targets laser-irradiated at intensity similar to10(19) W cm(2). The charge-up, detected via the proton deflection with high temporal and spatial resolution, is due to the escape of energetic electrons generated during the interaction. The analysis of the data is supported by three- dimensional tracing of the proton trajectories. (C) 2003 American Institute of Physics.

Doppler cooling of gallium atoms: 1. Fine structure effects and transient coherences

A realistic model of the dipole radiation forces in transverse Doppler cooling (with a s+-s- laser configuration) of an atomic beam of group 13 elements is studied within the quantum-kinetic equation framework. The full energy level sub-structure for such an atom with I = 0 (such as 66Ga) is analysed. Two cooling strategies are investigated; the first involving the 2P3/2 ? 2D5/2 transition and the second a dual laser cooling experiment involving transitions 2P1/2 and 2P3/2 ? 2S1/2. The latter scheme creates a velocity-independent dark-state resonance that inhibits a steady-state dipole cooling force. However, time-dependent calculations show that transient cooling forces are present that could be exploited for laser cooling purposes in pulsed laser fields.