Speaker
Dr
Masaki Hori
(Max Planck Institute for Quantum Optics)
Description
The ASACUSA collaboration at CERN's Antiproton Decelerator has precisely measured the atomic transition frequencies of antiprotonic helium by laser spectroscopy. These three-body exotic atoms are each composed of a normal helium nucleus, and electron, and an antiproton. They constitute baryon-antibaryon bound states with the longest known lifetime. The experiments involved cooling 2 billion atoms to temperature 1.5-1.7 K by employing gas buffer cooling in a cryogenic helium gas target. By comparing the results with QED calculations, the antiproton-to-electron mass ratio was determined as 1836.1526734(15). This agreed with the proton-to-electron mass ratio with a precision of 8x10^-10. The spectroscopic data has also recently been used to set experimental limits on any hypothetical fifth force at the 1 Angstrom length range.
Selected session
Fundamental Symmetries and Interactions
Primary author
Dr
Masaki Hori
(Max Planck Institute for Quantum Optics)
