We demonstrate a photon-counting technique for detecting Bragg excitation of an ultracold gas of atoms. By measuring the response of the light field to the atoms, we derive a signal independent of traditional time-of-flight atom-imaging techniques. With heterodyne detection we achieve photon shot-noise limited detection of the amplification or depletion of one of the Bragg laser beams. Photon c...

Electron correlations can be found in various fields of physics whenever we have to go beyond the independent particle model. A convenient method to study electron correlations in gas-phase atoms and molecules is to measure the probability to remove two electrons simultaneously with a single photon (called double photoionization) from the sample. Because a single photon can interact with only o...

The photon drag effect of a 2D electron gas is measured using the ps infrared pulses of the wavelength-tunable free electron laser source FELIX. The pulsed photon drag response is found to depend critically on the coupling characteristics of the electrical circuit. We therefore developed an impedance and velocity matched photon drag detector. It consists of a GaAs/ AlGaAs multi quantum well sam...

Betatron x-rays with multi-keV photon energies have been observed from a GeV-class laser-plasma accelerator. The experiment was performed using the 200 TW Callisto laser system at LLNL to produce and simultaneously observe GeV-class electron beams and keV Betatron x-rays. The laser was focused into various gas cells with sizes ranging from 3 to 10 mm, and containing mixed gases (He, N, CO2, Ar,...