Friday 18 May, 11.00h, at Nikhef in H331.
Speaker: Chris Rasmussen (Alpha Collaboration)
Title: “1S-2S Spectroscopy of Antihydrogen in the ALPHA Experiment”
Precision measurements of magnetically trapped antihydrogen provides a unique and powerful way to test matter-antimatter symmetries. A cornerstone of the standard model, CPT symmetry demands that the spectrum of antihydrogen be identical to that of its ordinary matter counterpart. Of particular interest is the 1S-2S transition which has been measured in hydrogen with the remarkable relative precision of a few parts in 1015, and promises a particularly elegant and high precision test of CPT symmetry by comparis onto antihydrogen.
In 2016, the ALPHA collaboration made the first observation of the 1S-2S transition in antihydrogen, and very recently this measurement was drastically improved to reach
a fractional precision of 2x 10-12. The observed frequency in antihydrogen is consistent with CPT symmetry at the current level of precision.
In this talk, I will present this latest measurement of the 1S-2S transition and introduce the methods of anti-atom spectroscopy developed by ALPHA. Finally, I will touch on future improvements needed to take this milestone measurement to the same precision as its hydrogen counterpart.
 Parthey, C.G. et al, Phys. rev. lett. 107, 203001 (2011).
 Ahmadi, M. et al, Nature 541, 506-510 (2017).
 Ahmadi, M et al, Nature (2018)