Description
Colliding high intensity laser pulses promises to be a pathway to measuring vacuum photon-photon scattering in the optical regime. An experiment is currently being set up at the Centre for Advanced Laser Applications (CALA) in Garching near Munich to search for photon-photon scattering with the ATLAS-3000 Petawatt class laser. We plan to collide two beams of same wavelength in a counter-propagating geometry. The signal will be collected in the shadow of the beams created by an annular beam profile. In this setup, we expect a few (<10) photons to scatter into our detector per shot. This signal will be accompanied by unwanted background contributions attributable to stray scattered light from optics and other surfaces, as well as scattering from the residual gas. While colliding two pulses is currently not yet possible in the setup, we are able to study these background contributions in detail. We will present the design, theoretical predictions and current state of the experiment as well as background measurement results. So far, these indicate we may be able to measure photon-photon scattering in the all-optical regime for the first time in the near future.
