Delbrück scattering

The various calculations of the Delbrück scattering amplitude are presented. This is followed by some generalities on the elastic scattering of photons by heavy atoms and finally by a review of the experiments together with a comparison with the calculations.     

Observations of high-voltage atmospheric-pressure spark discharges in argon using a charge-coupled device detector

Charge-Coupled Device (CCD) detection of emission from a high voltage atmospheric pressure spark has shown behaviors previously not detectable. These include variation in the distance of excitation propagation from the cathodic electrode from spark to spark, even when the electrode surface is mechanically well defined. Line shape for emission from single sparks was observed, and the change in line shape on successive sparks during “burnout” documented. Spectral line shape as a function of time and space was monitored with a reliably linear two-dimensional detector. Observed behavior is in contrast to accepted models, in that previous integrated data are seen to be summations over qualitatively different sequential sparks, rather than averages of identical sparks.