Dark matter detector. Frontal view of the cryostat of the PVLAS (Polarizzazione del Vuoto con Laser) optical apparatus. The cryostat contains PVLAS's superconductor magnet, which it keeps at an extremely low temperature. The PVLAS is used to search for the presence of dark matter by detecting the small flattening acquired by a linearly polarised laser beam after it passes through a vacuum space where an intense magnetic field has been applied. Photographed at the Legarno National Laboratory, National Institute of Nuclear Physics, Padova, Italy.