Testing the Pauli Exclusion Principle for Electrons at LNGS

Abstract

High-precision experiments have been done to test the Pauli exclusion principle (PEP) for electrons by searching for anomalous K-series X-rays from a Cu target supplied with electric current. With the highest sensitivity the VIP (VIolation of Pauli Exclusion Principle) experiment set an upper limit at the level of 10−29 for the probability that an external electron captured by a Cu atom can make the transition from the 2p state to a 1s state already occupied by two electrons. In a follow-up experiment at Gran Sasso, we aim to increase the sensitivity by two orders of magnitude. We show proofs that the proposed improvement factor is realistic based on the results from recent performance tests of the detectors we did at Laboratori Nazionali di Frascati (LNF)

Test of the Pauli Exclusion Principle in the VIP-2 Underground Experiment

“…Finally, in addition to the improved passive shielding surrounding the setup to reduce the background generated by the environmental radiations, the use of silicon drift detectors (SDDs) as the X-ray detectors allows the implementation of an active shielding using scintillators, as illustrated in Figure 1a, which removes the background induced by the high-energy charged particles that are not shielded. More details of the detectors and the VIP-2 setup are given in [12][13][14][15]. The VIP-2 trigger logic was implemented using the Nuclear Instrumentation Module (NIM) standard modules, and it is defined by either an event at any SDD or a coincidence between two layers of the veto detector.…”

Experimental search for the violation of Pauli exclusion principle

“…Using the electron and positron test beam at BTF, we measured the efficiency and the response of the scintillator with SiPM readout to the charged particles. The confirmed efficiency of above 97% and the time response of 2 ns [21] were sufficient to identify cosmic ray events that lead to background at the SDDs. With the detectors and the trigger logic assembled at SMI, we tested the veto scintillators together with the SDDs.…”

Searches for the violation of Pauli exclusion principle at LNGS in VIP(-2) experiment

“…By introducing new X-ray detectors and an active shielding, as listed in the Table 1, the VIP-2 experiment expects to further improve the sensitivity by two orders of magnitude. The detectors and the setup of the VIP-2 experiment are introduced by more detail in [11] from this conference proceedings and in [12,13],…”