Precision gamma- and x-ray energies. Final report

At this time, it has been possible to redetermine a small but significant group of gamma-ray reference energies (0.6 less than E less than 1.1 MeV) in terms of the Rydberg constant, R (infinity). This work has made use of an I2 molecularly stabilized laser to link Doppler-free spectroscopy of hydrogen with achromatic procedures for crystal spacing determination. Crystals calibrated in this way (after suitable transfer measurements) have been used to determine X-ray and gamma-ray transition energies using flat-crystal instruments whose angular scales were established to high accuracy from first principles. The authors main aim is to summarize applications thus far, and to examine the technical problems and potential interest which may follow from extension of these techniques to higher energies.