Nobel prize to H. G. Dehmelt and W. Paul awarded in 1989 "for the development of the ion trap technique''. Co-winner N. F. Ramsey "for the invention of the separated oscillatory fields method and its use in the hydrogen maser and other atomic clocks''
VAN DYCK 1987
Van Dyck, R.S.; Schwinberg, P.B.; Dehmelt, H.G.; New High Precision Comparison of Electron and Positron g Factors
Phys. Rev. Lett. 59 (1987) 26;
Single electrons and positrons have been alternately isolated in the same compensated Penning trap in order to form the geonium pseudoatom under nearly identical conditions. For each, the g-factor anomaly is obtained by measurement of both the spin-cyclotron difference frequency and the cyclotron frequency. A search for systematic effects uncovered a small (but common) residual shift due to the cyclotron excitation field. Extrapolation to zero power yields e+ and e- g factors
with a smaller statistical error and a new particle-antiparticle comparison: g(e-)/g(e+) = 1 + (0.5 ± 2.1) x 10-12.
Related references More (earlier) information appears in P. B. Schwinberg, R. S. van Dyck, and H. G. Dehmelt, Phys. Rev. Lett. 47 (1981) 1679;
R. S. van Dyck, P. B. Schwinberg, and H. G. Dehmelt, Phys. Rev. D34 (1986) 722;
P. B. Schwinberg, R. S. van Dyck, and H. G. Dehmelt, Phys. Lett. 81A (1981) 119;
High precision measurements of electron and positron g-2 factors. High precision test of QED and CPT symmetry.