Determination of the antiproton-to-electron mass ratio by precision laser spectroscopy of pHe+.
A femtosecond optical frequency comb and continuous-wave pulse-amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of (9-16)x10(-9). One of these is between two states having microsecond-scale lifetimes hitherto unaccessible to our precision laser spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio of Mp/me=1836.152674(5).
Hori
M
M
CERN, CH-1211 Geneva 23, Switzerland.
Dax
A
A
Eades
J
J
Gomikawa
K
K
Hayano
R S
RS
Ono
N
N
Pirkl
W
W
Widmann
E
E
Torii
H A
HA
Juhász
B
B
Barna
D
D
Horváth
D
D