Precise measurement of hyperfine splitting of positronium using the Zeeman effect

Akira Ishida, Ginga Akimoto, Yuichi Sasaki, Taikan Suehara, Toshio Namba, Shoji Asai, Tomio Kobayashi, Haruo Saito, Mitsuhiro Yoshida, Kenichi Tanaka, Akira Yamamoto

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The ground state hyperfine splitting of positronium, ΔHFS, is sensitive to high order corrections of QED. A new calculation up to O(α 3 lnα ) has revealed a 3.9 σ discrepancy between the QED prediction and the experimental results. This discrepancy might either be due to systematic problems in the previous experiments or to contributions beyond the Standard Model. We propose an experiment to measure ΔHFS employing new methods designed to remedy the possible systematic errors which may have affected the previous experiments. Our experiment will provide an independent check of the discrepancy. The prototype run has been performed and a result of ΔHFS = 203.3804 ± 0.0022 (stat., 11 ppm) ± 0.0081 (sys., 40 ppm) GHz has been obtained. Compensation magnets to obtain O(ppm) magnetic field uniformity has been developed. The final run will start soon and a measurement with a precision of O(ppm) is expected within a few years.

Original languageEnglish
Title of host publicationProgress in Positron Annihilation
PublisherTrans Tech Publications Ltd
Number of pages4
ISBN (Print)9780878492084
Publication statusPublished - 2011
Externally publishedYes

Publication series

NameMaterials Science Forum
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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