Phys. Rev. Lett. 90, 203402 (2003) [4 pages]Resolution of the Orthopositronium-Lifetime PuzzleReceived 18 March 2003; published 23 May 2003 The long-standing discrepancy [ G. S. Adkins, R. N. Fell and J. Sapirstein Ann. Phys. (N.Y.) 295 136 (2002)] between the theoretical calculations of the orthopositronium (o-Ps) annihilation decay rate (λT=1/lifetime) and some of the experimental measurements has been resolved. A focused beam of positrons incident on a special nanoporous silica film produces near-thermal energy o-Ps in vacuum that is slow enough to be virtually free of perturbing interactions. The fitted decay rate requires only a 500 ppm correction for nonthermal o-Ps effects. The new value of λT=7.0404(10)(8) μs-1 is in excellent agreement with theory. © 2003 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.90.203402
DOI:
10.1103/PhysRevLett.90.203402
PACS:
36.10.Dr, 11.10.St, 12.20.Fv
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