Direct Measurement of Positronium Hyperfine Splitting in Vacuum

2012 Fiscal Year Final Research Report

• Project/Area Number: 23740173
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: The University of Tokyo
• Principal Investigator: SUEHARA Taikan 東京大学, 素粒子物理国際研究センター, 特任研究員 (20508387)
• Project Period (FY): 2011 – 2012
• Keywords: ポジトロニウム / 超微細構造 / テラヘルツ / ジャイロトロン / 共振器

Research Abstract

We observed the direct transition between ortho-positronium and para-positronium using 203 GHz high power radiation to measure the hyperfine splitting of positronium. With a high power radiation source, gyrotron, and a Fabry-Perot cavity with golden mesh mirror on a high-resistivity silicon, we succeeded to observe the transition of more than 10 sigma significance. We also measured the transition curve with measurements using radiation of multiple frequencies.

Research Products

• [Journal Article] Direct Observation of the Hyperfine Transition of Ground-State Positronium (2012)
  • Author(s): T. Yamazaki, A. Miyazaki, T. Suehara,T. Namba, S. Asai, T. Kobayashi, H. Saito, I. Ogawa, T. Idehara, S. Sabchevski
  • Journal Title: Physical Review Letters Volume: 108 Pages: 253401
  • DOI: DOI:10.1103/PhysRevLett.108.253401
  • Peer Reviewed
• [Journal Article] The First Direct Observation ofPositronium Hyperfine Splitting (2012)
  • Author(s): T. Suehara, T. Yamazaki, A. Miyazaki, G. Akimoto, A. Ishida, T. Namba, S. Asai, T. Kobayashi, H. Saito, T. Idehara, I. Ogawa, S. Sabchevski
  • Journal Title: AIP Conference Proceedings Volume: 1441 Pages: 549-551
  • DOI: DOI:http://dx.doi.org/10.1063/1.3700613
  • Peer Reviewed
• [Journal Article] New Experiment for the First Direct Measurement of Positronium Hyperfine Splitting with Sub-THz Light (2011)
  • Author(s): A. Miyazaki, T. Yamazaki, T. Suehara, T. Namba, S. Asai, T. Kobayashi, H. Saito, T. Idehara, I. Ogawa, Y. Urushizaki, S. Sabchevski
  • Journal Title: Materials Science Forum Volume: 666 Pages: 133-136
  • DOI: DOI:10.4028/www.scientific.net/MSF.666.133
  • Peer Reviewed
• [Presentation] Direct Measurement of the Hyperfine Transition of Positronium using High Power Sub-THz Radiation (2013)
  • Author(s): 山崎高幸
  • Organizer: 日本物理学会第 68回年次大会
  • Place of Presentation: 広島大学(広島県)(招待講演)
  • Year and Date: 2013-03-28
• [Presentation] The direct spectroscopy of positronium hyperfine structure using sub-THz gyrotron (2012)
  • Author(s): Akira Miyazaki
  • Organizer: International Symposium on Frontiers in THz Technology
  • Place of Presentation: Todaiji Culture Center (Japan)(招待講演)
  • Year and Date: 2012-11-27
• [Presentation] Direct measurement of the Hyperfine Structure of the Groundstate Positronium using High Power sub-THz radiation (2012)
  • Author(s): Takayuki Yamazaki
  • Organizer: The 37th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)
  • Place of Presentation: Wollongong (Australia)
  • Year and Date: 2012-09-28
• [Presentation] The First Direct Observation of Positronium Hyperfine Splitting (Ps-HFS) (2012)
  • Author(s): Taikan Suehara
  • Organizer: The 19th Particles and Nuclei International Conference
  • Place of Presentation: Boston (USA)
  • Year and Date: 2012-07-25
• [Presentation] The first observation of direct transition between o-Ps and p-Ps by sub-THz radiation (2011)
  • Author(s): Taikan Suehara
  • Organizer: Cold Antimatter and High Precision Physics (Pbar11)招待講演
  • Place of Presentation: Matsue (Japan)
  • Year and Date: 2011-11-29
• [Remarks]
  • URL: http://tabletop.icepp.s.u-tokyo.ac.jp/Tabletop_experiments/Direct_HFS_measurement.html