The decay rate of ortho-positronium in vacuum

Griffith, T C; Heyland, G R; Lines, K S; Twomey, Tae

doi:10.1088/0022-3700/11/23/007

Cited by 27 publications

(2 citation statements)

References 13 publications

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“…Many measurements of the triplet Ps decay rate have been performed [163,[191][192][193][194][195][196], driven by an apparent discrepancy with theory. However, this now appears to have been an experimental artifact related to incomplete Ps thermalization processes; the most recent measurements found Γ ( 3 S 1 ) = 7.0404(10)(8) MHz, in agreement with theory [82,83,197].…”

Section: Ps Annihilationmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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Abstract. The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥10 6 ) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 10 7 cm −3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

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Section: Ps Annihilationmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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“…The Detroit value is in agreement with estimates of this parameter made by Dababneh et a1 (1980). Stein and Kauppila (1982) have also pointed to a possible error in the analysis of Griffith et al (1978a) due to scattering in the 0.15 m long curved solenoid located at the end of the flight path in the original experiment at UCL. Stein and Kauppila (1982) argue that, due to the positioning of the coils, the figure of Od,sc= 10" only applies to the 0.7 m long straight section of the flight path with positrons scattering in the curved region, which was maintained at a roughly constant magnetic field, being virtually indistinguishable from the unscattered beam.…”

Section: Total Cross Sectionsmentioning

confidence: 99%

Experimental studies of positrons scattering in gases

Charlton¹

1985

Rep. Prog. Phys.

166

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The current status of certain aspects of positron scattering in gases is reviewed. A brief resume of the experimental techniques used in this field is also given.Results for total scattering cross sections in a number of gases are presented along with a detailed discussion of potential systematic errors which can affect such measurements. Important features of the cross sections are pointed out and comparisons are made with electron scattering data.Results from experiments which go beyond total cross section determinations are discussed. Emphasis is placed upon recent measurements of positronium formation cross sections.Recent positron lifetime studies in dense gases are reviewed. The subjects covered include positron annihilation in clusters, ortho-positronium annihilation in bubbles and positronium formation in spurs.

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Two-Loop Correction to the Orthopositronium Decay Rate

2002

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We give a detailed description of our calculation of the O(α 2 ) correction to the orthopositronium decay rate. The resulting correction is 45.06(26) in units of (α/π) 2 times the lowest order rate. When combined with other known corrections, the theoretical prediction for the decay rate is 7.039979(11) µs −1 , where the leading uncalculated term makes an estimated contribution of roughly 0.00002 µs −1 . Our result is in significant disagreement with two of the four highest precision measurements (at about the 5σ level), but does not contradict the others. The experimental uncertainties (≈0.002 µs −1 ) are much larger than the remaining theoretical uncertainties. We also calculate the one-photon-annihilation contribution to the positronium hyperfine structure at O(mα 6 ). This calculation is closely analogous to the decay rate calculation. Our agreement with prior results for this hyperfine structure contribution demonstrates the soundness of our approach. C 2002 Elsevier Science (USA)

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The decay rate of ortho-positronium in vacuum

Cited by 27 publications

References 13 publications

Experimental progress in positronium laser physics

Experimental progress in positronium laser physics

Experimental studies of positrons scattering in gases

Two-Loop Correction to the Orthopositronium Decay Rate

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