E. Redd

Microprocessor‐based pressure controller

A device for automatic control of pressure in an ion‐atom scattering experiment has been constructed. The system was modeled to achieve the minimum time for transition from one pressure to another. The pressure controller ‘‘learns’’ the system response and iterates the parameters used in ‘‘profiling’’ the valve voltage to reduce the transition time. The device has been used with two different scattering chambers and has worked well with both.

Reactive scattering cell for atomic hydrogen and deuterium

A design for a high‐temperature reactive scattering cell for atomic hydrogen and atomic deuterium is described. At approximately 2700 K a dissociation of the molecular target species of over 95% has been obtained. The lifetime of 340 h of operation is sufficient for precision, long‐time, differential cross‐section measurements.

Charge Transfer in Quasi-One-Electron Systems at 'High' Energy

The authors have made absolute and relative measurements of differential cross sections for single-electron transfer in collisions between Mg+ (30-150 keV) and Be+ (56.25 keV) ions and He atoms. The behaviour of transfer probability as a function of impact parameter can be understood qualitatively from recent molecular orbital calculations of quasi-one-electron systems.