VIP 2: Experimental tests of the Pauli Exclusion Principle for electrons

TL;DR

The VIP 2 experiment aims to test the Pauli Exclusion Principle for electrons with higher sensitivity, using improved detection methods to set more stringent limits on possible violations.

Contribution

This paper reports on the ongoing performance tests of the upgraded VIP 2 setup designed to improve the upper limit for PEP violation detection.

Findings

Preliminary upper limit for PEP violation probability is 4.7 x 10^{-29}

Enhanced energy resolution of detectors is being implemented

Active shielding is being integrated to reduce background noise

Abstract

Many experiments investigated the violation of the Pauli Exclusion Principle (PEP) since its discovery in 1925. The VIP (VIolation of the Pauli Principle) experiment tested the PEP by measuring the probability for an external electron to be captured and undergo a 2p to 1s transition during its cascading process, where the 1s state is already occupied by two electrons. This transition is forbidden by the Pauli Exclusion Principle. The VIP experiment resulted in a preliminary upper limit for the probability of the violation of the PEP of 4.7 x 10^{-29}. Currently a setup for the follow-up experiment VIP 2 is under preparation. The goal of this experiment is to improve the upper limit for the violation of the PEP by two orders of magnitude, by different improvements like enhanced energy resolution of the X-ray detectors and by implementing an active shielding. Here we report currently ongoing performance tests of the new parts of the setup.