When compared to their matter counterparts, precision measurements of antiprotons
such as the one of their charge-to-mass ratio [1] or of antihydrogen provide very
stringent tests of the CPT symmetry (charge conjugation, parity and time reversal) that is fundamental to our formulation of the Standard Model of particle physics in terms of Lorentz invariant, local quantum field theories.
At ATRAP, this type of research is currently pursued along two aspects. One goal is to
perform precise spectroscopy of antihydrogen in a magnetic atom trap. Here, a
milestone has recently been accomplished by simultaneously trapping 5 antihydrogen
atoms on average with confinement times of 15 to 1000 s- long enough to ensure that
they have reached their ground state [2].
A second goal is to precisely determine the antiproton’s magnetic moment μp. By
utilizing one-particle methods in a Penning trap [3,4,5] ATRAP has performed the first
direct measurement of μp with a precision of 4.4 parts per million [6], a 680-fold
improvement over the previous values [7]. These techniques that can be applied to
both, proton and antiproton, ultimately promise a gain in experimental precision of μp by at least a factor of 103 in addition to the present measurement. This has been
demonstrated recently with a proton measurement by the BASE collaboration [8].
This talk will present recent progress in ATRAP’s anti-hydrogen efforts as well as the
first direct measurement of the anti-proton’s magnetic moment.
[1] G. Gabrielse et al., Phys. Rev. Lett. 82, 3198 (1999)
[2] G. Gabrielse et al., Phys. Rev. Lett. 108, 113002 (2012)
[3] N. Guise, J. DiSciacca, and G. Gabrielse, Phys. Rev. Lett. 104, 143001 (2010)
[4] S. Ulmer et al., "Phys. Rev. Lett. 106, 253001 (2011)
[5] J. DiSciacca and G. Gabrielse, Phys. Rev. Lett. 108, 153001 (2012)
[6] J. DiSciacca et al., Phys. Rev. Lett. 110, 130801 (2013)
[7] T. Pask et al., Phys. Lett. B 678, 55 (2009)
[8] A. Mooser et al., Nature 509, 596 (2014)
