A Study of Positron Properties in Quartz Crystals and Synthetic Silica Glass

The monoenergetic positron beamline ‚SPONSOR' at Rossendorf has been used to investigate the positron behaviour in a naturally grown Brasilian quartz, two synthetic quartz crystals of different origin, and synthetic silica glass. The measurements allow to obtain the positron diffusion length of free positrons and Bloch para-positronium (p-Ps), if formed, in these materials.
In addition, hydrothermal treatment of a synthetic quartz has been used to introduce hydrogen into the crystal up to a certain depth. The presence of hydrogen is found to influence the formation of p-Ps. The depth distribution of hydrogen has been measured independently by nuclear reaction analysis (NRA), and will be discussed in comparison with the depth results deduced from the positron studies.