Positronium formation in gaseous ethane and ethane–Ne mixtures

Abstract

The positronium yields have been measured in gaseous ethane at gas densities in the range 0.1–286 amagat at 256, 294, 306, 307, 310, 323, 343, and 377 K and in ethane–neon mixtures having neon concentrations from about 0.38 to 0.99 at 256, 294, and 306 K. The positronium yields in gaseous ethane are observed to vary with gas density in a complex manner and to remain independent of temperature for the range of temperatures investigated. The presence of neon in ethane–neon mixtures enhances the fraction of positrons forming positronium at low partial densities of ethane. These results are discussed in terms of the models for positronium formation.