Spontaneous Emission of Positronium Negative Ions from Tungsten (100) Surface

Abstract

Recently, we have observed spontaneous emission of positronium negative ions from polycrystalline tungsten surface. In the present work, we have extended the study to the emission from tungsten single crystal. The emission from tungsten (100) surface plane has been confirmed. The fraction of positrons yielding the ions at the target surface was ()4102.02.1−×±.

Emission of positronium negative ions from Cs deposited W(100) and polycrystalline Fe surfaces

“…In 2006, we reported that a small fraction of slow positrons which impinge on W surfaces are emitted as Ps -spontaneously [3]. However, the emission efficiencies were 0.006-0.012% [3][4][5][6], and lower than that obtained using the beam foil method [7][8][9].…”