Abstract
A direct measurement is reported of the velocity of positronium (Ps) ejected into a vacuum when 0- to 100-eV positrons (e+) strike a negatively biased Cu(111) surface. At 30 °C, about half the e+ form Ps with normal energy component Ē=3.4(3) eV. At 790 °C, most of the remaining e+ form Ps but with Ē=0.14(1) eV, and a non-Maxwellian thermal distribution. We infer that surface-bound e+ are thermally desorbed to form the extra Ps. These low Ps velocities suggest exciting possibilities for experiments on free Ps.
Original language | English (US) |
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Pages (from-to) | 1961-1964 |
Number of pages | 4 |
Journal | Physical review letters |
Volume | 43 |
Issue number | 26 |
DOIs | |
State | Published - 1979 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy