Friday 18 May, 11.00h, at Nikhef in H331.
Speaker: Chris Rasmussen (Alpha Collaboration)
Title: “1S-2S Spectroscopy of Antihydrogen in the ALPHA Experiment”
Abstract:
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[1] 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[2] of the 1S-2S transition in antihydrogen, and very recently this measurement was drastically improved[3] 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.
[1] Parthey, C.G. et al, Phys. rev. lett. 107, 203001 (2011).
[2] Ahmadi, M. et al, Nature 541, 506-510 (2017).
[3] Ahmadi, M et al, Nature (2018)