PVLAS
Experiment - Home
Nonlinear
effects in electromagnetic processes in vacuum have been sought after
for many years after having been predicted by Euler and Heisenberg in
their effective Lagrangian published in 1936. The only input to their
calculation was the Heisenberg uncertainty principle leading to virtual
pair creation, which allowed photons to interact with each other.
The direct measurement of this effect is yet to be seen and has been
the aim of the PVLAS experiment since its beginnings. The PVLAS
experiment, financed by the Italian Istituto Nazionale di Fisica
Nucleare (INFN), is located at the
Laboratori Nazionali di Legnaro of INFN (LNL), Padova, Italy.
The setup consists of a sensitive ellipsometer attempting to detect the
small changes in the polarization state of light propagating through a
1 m long magnetic field region in vacuum. It is based on a high finesse
Fabry-Perot cavity and a superconducting 5 T rotating dipole magnet.
Indeed, vacuum will become birefringent in the presence of a strong
magnetic field. A possible secondary effect, which could mask the
vacuum magnetic birefringence, could be due to the existence of a
light, neutral pseudoscalar/scalar particle coupling to two photons via
the Primakoff effect.
Panorama view of the experiment (2006)
Panorama view of the experiment (2008)
Check this link for a more detailed review
of the experiment, and this
link for a list of past and present members of PVLAS.
Additional
information
Webmaster:
Edoardo Milotti - Last
update: january 2009