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Particles and Nuclei International Conference (PANIC)

Testing Pauli Exclusion Principle for electrons at the LNGS underground laboratory: The VIP-2 experiment

Luca De Paolis, Fabrizio Napolitano, Kristian Piscicchia, Sergio Bartalucci, S. Bertolucci, M. Bazzi, Mario Alexandru Bragadireanu, M. Cargnelli, A. Clozza, Carlo Ettore Fiorini, C. Guaraldo, Mihai Iliescu, Matthias Laubenstein, Johann Marton, Marco Miliucci, E. Milotti, Alessio Porcelli, A. Scordo, Francesco Sgaramella, Hexi Shi, Florin Catalin Sirghi, Johann Zmeskal, Catalina Curceanu, R. Del Grande, Diana Laura Sirghi

Published Mar 2, 2022• 0 citations
Publisher

Abstract

The VIP-2 experiment tests the Pauli Exclusion Principle (PEP) for electrons at the Gran Sasso underground National Laboratory (LNGS) of INFN in Italy, looking for a possible violation. The LNGS provide an extremely low background environment, ideal for performing high precision X-ray spectroscopy measurements on electrons atomic transitions. The core of the VIP-2 experimental apparatus is based on a copper target circulated by a Direct Current (DC) and surrounded by silicon drift detectors (SDDs), which offer excellent performance in X-ray spectroscopy in the energy range experimentally observed by VIP-2. The aim of VIP-2 is to look for eventual PEP-forbidden K$\alpha$ transitions (2p $\rightarrow$ 1s) in copper atoms, when the 1s level would be already occupied by two electrons, in contradiction with PEP. The energy of the K$\alpha$ forbidden transitions is about 300 eV less than the nominal energy of the K$\alpha$ PEP-allowed transition. This energy shift is due to the screening effect produced by the extra electron in fundamental level, and is detectable by means of a high precision X-ray spectroscopy measurement. About ten years ago, the VIP experiment set the best upper limit on the PEP violation probability $\beta^2/2<$4.7$~\times~10^{-29}$ for electrons. The goal of the VIP-2 experiment is to improve this limit by two orders of magnitude. This paper presents a new preliminary result, obtained by analysing two sets of data collected with a partial configuration of the VIP-2 apparatus.

DOI
10.22323/1.380.0456

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The VIP-2 experiment tests the Pauli Exclusion Principle (PEP) for electrons at the Gran Sasso underground National Laboratory (LNGS) of INFN in Italy, looking for a possible violation. The LNGS provide an extremely low background environment, ideal for performing high precision X-ray spectroscopy measurements on electrons atomic transitions. The core of the VIP-2 experimental apparatus is based on a copper target circulated by a Direct Current (DC) and surrounded by silicon drift detectors (SDDs), which offer excellent performance in X-ray spectroscopy in the energy range experimentally observed by VIP-2. The aim of VIP-2 is to look for eventual PEP-forbidden Kα\alphaα transitions (2p →\rightarrow→ 1s) in copper atoms, when the 1s level would be already occupied by two electrons, in contradiction with PEP. The energy of the Kα\alphaα forbidden transitions is about 300 eV less than the nominal energy of the Kα\alphaα PEP-allowed transition. This energy shift is due to the screening effect produced by the extra electron in fundamental level, and is detectable by means of a high precision X-ray spectroscopy measurement. About ten years ago, the VIP experiment set the best upper limit on the PEP violation probability β2/2<\beta^2/2<β2/2<4.7 × 10−29~\times~10^{-29} × 10−29 for electrons. The goal of the VIP-2 experiment is to improve this limit by two orders of magnitude. This paper presents a new preliminary result, obtained by analysing two sets of data collected with a partial configuration of the VIP-2 apparatus.
We are experimentally investigating possible violations of standard quantum mechanics predictions in the Gran Sasso underground laboratory in Italy. We test with high precision the Pauli Exclusion Principle and the collapse of the wave function (collapse models). We present our method of searching for possible small violations of the Pauli Exclusion Principle (PEP) for electrons, through the search for "anomalous" X-ray transitions in copper atoms. These transitions are produced by "new" electrons (brought inside the copper bar by circulating current) which can have the possibility to undergo Pauli-forbidden transition to the 1s level already occupied by two electrons. We describe the VIP2 (VIolation of the Pauli Exclusion Principle) experimental data taking at the Gran Sasso underground laboratories. The goal of VIP2 is to test the PEP for electrons in agreement with the Messiah-Greenberg superselection rule with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10 −31 . We show preliminary experimental results and discuss implications of a possible violation.
The VIP-2 (VIolation of the Pauli Exclusion Principle) experiment conducted at the Gran Sasso underground laboratory (LNGS) of INFN is searching for possible tiny violations of standard quantum mechanics in copper atoms with extremely high sensitivity. We investigate atomic transitions with precision X-ray spectroscopy in order to test the Pauli Exclusion Principle (PEP) and therefore the spin-statistics theorem. We present the experimental method for the search for "anomalous" (i.e. Pauli-forbidden) X-ray transitions in copper atoms, produced by "new" electrons, which could have a tiny probability to undergo a Pauli-forbidden transition to the 1s ground state already occupied by two electrons. We describe the VIP-2 experimental setup and its recent optimisations. Presently VIP-2 is taking data at LNGS. The goal of VIP-2 is to test PEP for electrons with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10 −31 (and using a more elaborate analysis even 10 −40 ). We present current experimental results.
Abstract The VIP2 (VIolation of the Pauli Exclusion Principle) experiment at the Gran Sasso underground laboratory (LNGS) is searching for possible violations of standard quantum mechanics predictions in atoms at very high sensitivity. We investigate atomic transitions with precision X-ray spectroscopy in order to test the Pauli Exclusion Principle (PEP) and therefore the related spin-statistics theorem. We will present our experimental method for the search for “anomalous” (i.e. Pauli-forbidden) X-ray transitions in copper atoms, produced by “new” electrons, which could have tiny probability to undergo Pauli-forbidden transition to the ground state already occupied by two electrons. We will describe the VIP2 experimental setup, which is taking data at LNGS presently. The goal of VIP2 is to test the PEP for electrons with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10−31. We will present current experimental results and discuss implications of a possible violation.
The Pauli Exclusion Principle (PEP) is a fundamental law in physics, governing the behavior of fermionic particles. The VIP2 Experiment tests this principle with high sensitivity, by search for Pauli-forbidden atomic transitions from the 2p to the 1s shell in copper. The principle of the experiment is to introduce “new” electrons into a copper conductor via a current. The electrons have the possibility to form states with a symmetric component with the atoms of the conductor. These states would violate the Pauli Exclusion Principle. A possible violation is observed by detecting and counting X-rays, originating from the conductor. The transition energy of Pauli-forbidden Kα X-rays is shifted in energy by 300 eV with respect to the normal Kα line. This energy difference can be resolved using Silicon Drift Detectors. From the number of photons in the energy region, where the Pauli-forbidden transition is expected, an upper limit for the probability of a violation of the PEP can be calculated. The thesis starts by explaining the physics behind the VIP2 experiment. Subsequently, the experimental setup is discussed, including: Silicon Drift detectors for X-ray detection, scintillators with Silicon photomultiplier readout for active shielding, a cryogenic system for cooling the detectors and a data acquisition system and an experiment control system. The data taken with the described setup in Vienna and in the underground laboratory in Gran Sasso (LNGS) is compared to simulations. The data selection and the detector calibration is described in detail. The final chapter deals with different methods for the analysis of the data taken at LNGS.
The Pauli Exclusion Principle (PEP) was famously discovered in 1925 by the austrian physicist Wolfgang Pauli. Since then, it underwent several experimental tests. Starting in 2006, the VIP (Violation of the Pauli Principle) experiment looked for 2p to 1s X-ray transitions in copper, where 2 electrons are present in the 1s state before the transition happens. These transitions violate the PEP, and the lack of detection of the corresponding X-ray photons lead to a preliminary upper limit for the violation of the PEP of 4.7 * 10^(-29). The follow-up experiment VIP 2 is currently in the testing phase and will be transported to its final destination, the underground laboratory of Gran Sasso in Italy, in autumn 2015. Several improvements compared to its predecessor like the use of new X-ray detectors and active shielding from background gives rise to a goal for the improvement of the upper limit of the probability for the violation of the Pauli Exclusion Principle of 2 orders of magnitude.
Abstract In the VIP2 VIolation of the Pauli Exlusion Principle (PEP) experiment at the Gran Sasso underground laboratory (LNGS) we are searching for possible violations of standard quantum mechanics predictions. With high precision we investigate the Pauli Exclusion Principle and the collapse of the wave function (collapse models). We will present our experimental method of searching for possible small violations of the Pauli Exclusion Principle for electrons, via the search for “anomalous” X-ray transitions in copper atoms, produced by “new” electrons (brought inside a copper bar by circulating current) which could have the probability to undergo Pauli-forbidden transition to the ground state (1 s level) already occupied by two electrons. We will describe the concept of the VIP2 experiment taking data at LNGS presently. The goal of VIP2 is to test the PEP for electrons with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10−31. We will show preliminary experimental results obtained at LNGS and discuss implications of a possible violation.