Speaker
Alexey Grinin
(MPQ Garching)
Description
High precision spectroscopy has been always the driving force for new fundamental theories
in physics. The so called proton size problem is a so far unexplained disagreement of the value of the proton charge radius extracted from the muonic spectroscopy, hydrogen spectroscopy and elastic electron-proton scattering by more than 5 sigma \cite{Antognini2013}.
Our experiment is highly suitable to verify or falsify the true existence of this problem since it is based on a completely different spectroscopy method than previously performed hydrogen spectroscopy experiments. \newline
In our experiment we were able recently to give a preliminary value of the 1s3s two-photon transition frequency with an accuracy of 17kHz for the first time with the Direct Frequency Comb Spectroscopy (DFCS) \cite{Baklanov1977}. This measurement was limited by an so far unobserved effect, which occurs in DFCS with chirped pulses and atomic beams. It can be understood as Chirp-Induced First Order Residual Doppler Shift (FORDS) and it is an important effect for future XUV and VUV DFCS experiments. \newline
In our setup we produce a frequency comb at 205 nm (2ps) by two subsequent frequency
doubling cavities from a Ti:Sa mode-locked laser at 820 nm \cite{Peters2013}. The atomic beam of hydrogen atoms is excited in an enhancement cavity and photons from 3s2p transition are collected and detected.
Authors
Alexey Grinin
(MPQ Garching)
Dr
Artur Matveev
(MPQ Garching)
Prof.
Dylan Yost
(Colorado State University)
Prof.
T.W. Hänsch
(MPQ Garching)
Dr
Thomas Udem
(MPQ Garching)
