The key role of the Silicon Drift Detectors in testing the Pauli Exclusion Principle for electrons: the VIP-2 experiment

The VIP experiment performed an accurate investigation of the Pauli Exclusion Principle for electrons. The apparatus was installed in the Gran Sasso Laboratories of the National Institute of Nuclear Physics in Italy, an underground environment with an extremely low cosmic background. The aim of the experiment was to test the Pauli Exclusion Principle for electrons in a copper target circulated by a Direct Current (DC) current, searching for X-rays emission due to an atomic transition forbidden by Pauli exclusion principle, from the L shell to the K shell of copper when the K shell is already occupied by two electrons. VIP set an upper limit on the Pauli exclusion principle violation probability ½ beta^2 <4.7 x 10^–29. The goal of the upgraded VIP-2 experiment, presently in data taking at Gran Sasso Laboratories, is to improve this limit by two orders of magnitude. The VIP-2 experimental apparatus, in which the Silicon Drift Detectors have the key role of X-ray detectors, and preliminary results are presented.