Electro-optic sampling of near-infrared waves, and attosecond polarization spectroscopy (Dr. Karpowicz) / Laser spectroscopy of pionic and antiprotonic helium atoms (Dr. Hori)
- Double Feature!
- Date: Apr 19, 2016
- Time: 02:30 PM - 04:00 PM (Local Time Germany)
- Speaker: Dr. N. Karpowicz, MPQ, Attosecond Physics Division / Dr. M. Hori, MPQ, Laser Spectroscopy Division
- Room: Herbert Walther Lecture Hall
- Host: MPQ
Electro-optic sampling of near-infrared waves, and attosecond
polarization spectroscopy (Dr. Karpowicz)
Direct access to the electric
field waveform of near-infrared and visible light allows for a detailed
view of light-matter interaction on the femtosecond or even attosecond
time scale. Two techniques, attosecond streaking and electro-optic
sampling, are able to provide this access, the latter being adopted from
the THz frequency range and recently improved in temporal resolution to
the point where field oscillations at 240 THz can be observed. I will
show how this has enabled direct reconstruction of the time-dependent
nonlinear polarization of materials interacting with strong laser fields
and the observation of sub-cycle energy exchange between a laser field
and solid and atomic targets. This approach to attosecond physics is
capable of providing sub-femtosecond time resolution without requiring
the sample under study to interact with extreme ultraviolet radiation,
presenting a number of new opportunities for experiments with extreme
temporal resolution.
Laser spectroscopy of pionic and antiprotonic
helium atoms (Dr. Hori)
The pion is the lightest and most long-lived
meson consisting of two valance quarks. Metastable pionic helium is a
heretofore hypothetical three-body atom composed of a helium nucleus, an
electron in the 1s-state, and a pion in a Rydberg state. In this talk,
we describe the latest efforts at achieving the first laser spectroscopy
of this atom using the Ring Cyclotron facility of the Paul Scherrer
Institute.Antiprotonic helium is a “cousin” of pionic helium, wherein an
antiproton replaces the pion. We recently attempted to cool down these
atoms to cryogenic temperatures by buffer gas cooling. By measuring the
transition frequencies very precisely, the antiproton-to-electron mass
ratio can be precisely determined, and compared with the
proton-to-electron value. The recent results of experiments carried out
at the Antiproton Decelerator facility of CERN will be presented.