The VIP (Violation of Pauli exclusion principle) experiment and its follow-up
experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for
X-rays from Cu atomic states that are prohibited by the Pauli Exclusion
Principle (PEP). The candidate events, if they exist, will originate from the
transition of a $2p$ orbit electron to the ground state which is already
occupied by two electrons. The present limit on the probability for PEP
violation for electron is 4.7 $\times10^{-29}$ set by the VIP experiment. With
upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment
will improve the sensitivity by two orders of magnitude.Comment: 5 pages, 3 figures, 1 table. Conference proceedings for oral
  presentation at TAUP 2015, Torin

Bartalucci, S.

Bertolucci, S.

Berucci, C.

Bragadireanu, A. M.

Cargnelli, M.

Clozza, A.

Curceanu, C.

d'Uffizi, A.

De Paolis, L.

Di Matteo, S.

Doce, O. Vazquez

Egger, J. -P.

Guaraldo, C.

Iliescu, M.

Ishiwatari, T.

Laubenstein, M.

Marton, J.

Milotti, E.

Pietreanu, D.

Piscicchia, K.

Ponta, T.

Sbardella, E.

Scordo, A.

Shi, H

Sirghi, D. L.

Sirghi, F.

Sperandio, L.

Vidal, A. Romero

Widmann, E.

Zmeskal, J.

Journal of Physics : Conference Series

English

arXiv

The VIP (Violation of Pauli exclusion principle) experiment and its follow-up experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays from Cu atomic states that are prohibited by the Pauli Exclusion Principle (PEP). The candidate events, if they exist, will originate from the transition of a 2p orbit electron to the ground state which is already occupied by two electrons. The present limit on the probability for PEP violation for electron is 4.7 ×10^-29 set by the VIP experiment. With upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by 2 orders of magnitude

Shi, H.

D'Ufflzi, A.

Egger, J. P.

MILOTTI, EDOARDO

Archivio istituzionale della ricerca - Università di Trieste

This content has been downloaded from IOPscience. Please scroll down to see the full text.Download details:IP Address: 151.38.93.178This content was downloaded on 16/06/2016 at 06:34Please note that terms and conditions apply.Searches for the violation of Pauli exclusion principle at LNGS in VIP(-2) experimentView the table of contents for this issue, or go to the journal homepage for more2016 J. Phys.: Conf. Ser. 718 042055(http://iopscience.iop.org/1742-6596/718/4/042055)Home Search Collections Journals About Contact us My IOPscienceSearches for the violation of Pauli exclusion principleat LNGS in VIP(-2) experimentH Shi1, S Bartalucci1, S Bertolucci2, C Berucci3,1, AM Bragadireanu1,4, M Cargnelli3, A Clozza1, C Curceanu1,4,5, L DePaolis1, S Di Matteo6, A d’Uffizi1, J-P Egger7, C Guaraldo1,M Iliescu1, T Ishiwatari2, J Marton2, M Laubenstein8, E Milotti9,D Pietreanu1,4, K Piscicchia1,5, T Ponta4, A Romero Vidal10,E Sbardella1, A Scordo1, D L Sirghi1,4, F Sirghi1,4, L Sperandio1,O Vazquez Doce11, E Widmann2 and J Zmeskal21INFN, Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati(Roma), Italy2CERN, CH-1211, Geneva 23, Switzerland3Stefan-Meyer-Institut fu¨r Subatomare Physik, Boltzmanngasse 3, 1090 Wien, Austria4IFIN-HH, Institutul National pentru Fizica si Inginerie Nucleara Horia Hulubbei, Reactorului30, Magurele, Romania5Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Piazza del Viminale 1,00183 Roma, Italy6Institut de Physique UMR CNRS-UR1 6251, Universite´ de Rennes1, F-35042 Rennes, France7Institut de Physique, Universite´ de Neuchaˆtel, 1 rue A.-L. Breguet, CH-2000 Neuchaˆtel,Switzerland8INFN, Laboratori Nazionali del Gran Sasso, S.S. 17/bis, I-67010 Assergi (AQ), Italy9Dipartimento di Fisica, Universita´ di Trieste and INFN-Sezione di Trieste, Via Valerio, 2,I-34127 Trieste, Italy10Universidade de Santiago de Compostela, Casas Reais 8, 15782 Santiago de Compostela,Spain11Excellence Cluster Universe, Technische Universita¨t Mu¨nchen, Boltzmannstraße 2, D-85748Garching, GermanyE-mail: hexishi@lnf.infn.itAbstract. The VIP (Violation of Pauli exclusion principle) experiment and its follow-upexperiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays fromCu atomic states that are prohibited by the Pauli Exclusion Principle (PEP). The candidateevents, if they exist, will originate from the transition of a 2p orbit electron to the groundstate which is already occupied by two electrons. The present limit on the probability for PEPviolation for electron is 4.7 ×10−29 set by the VIP experiment. With upgraded detectors forhigh precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by 2 ordersof magnitude.1. IntroductionIn quantum mechanics the Pauli exclusion principle can be formalized with two fundamentalprinciples. First, the states of identical particles are described in terms of wave functions.Second, with respect to the permutation of identical particles, the states are necessarily eitherXIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015) IOP PublishingJournal of Physics: Conference Series 718 (2016) 042055 doi:10.1088/1742-6596/718/4/042055Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing Ltd 1all symmetrical for bosons, or all antisymmetrical for fermions. The second part containsthe “symmetrization postulate” [1], which excludes mixing of different symmetrization groups.Messiah and Greenberg noted in [2] that this superselection rule “does not appear as a necessaryfeature of the QM description of nature.” In this context, the violation of PEP is equivalentto the violation of statistics [4], and experimentally to the existence of states of particles thatfollow the statistics other than the fermion or the boson ones.Exhaustive reviews of the experimental and theoretical searches for a small violation of thePEP or the violation of statistics can be found for example in [3] and [4]. We point out that firstly,there is no established model in quantum field theory that can include small violations of thePEP explicitly. Secondly, although many experimental searches present limits for the violation,the parameters that quantify the limits are model/system dependent and are not generallycomparable. Moreover, to search for states that are in an abnormal or a mixed symmetry, itis crucial to introduce into the system an abundance of new states, among which the abnormalstates may be found. Ramberg and Snow [5] took this argument into account, by running ahigh electric current through a Cu conductor, and they searched for X-rays from transitions thatare PEP-forbidden after one electron is captured by a Cu atom. Due to the shielding effect ofthe additional electron in the ground level, the energy of such abnormal transitions will deviatefrom the Cu Kα X-ray at 8 keV by about 200 eV [6], which will be distinguishable in precisionspectroscopy. Since the new electrons from the current are supposed to have no establishedsymmetry with the electrons inside the Cu atoms, the detection of the abnormal X-ray is anexplicit indication of the violation of statistics, and thus the violation of the PEP.We want to mention that, one known system in which the dichotomy of fermions andbosons does not work is in the 2-dimensional condensed matter physics through the (fractional)Quantum Hall effect [7]. Particles that are neither fermions nor bosons, and that may exist inelectronic systems confined to two spatial dimensions have been constructed theoretically andinvestigated in the laboratory with great consistency with the theories as reviewed in [8]. Thephysics of this special system is exciting in itself and may provide hints to the searches for theviolation of the exclusion principle in other systems.Table 1. The improvement factors for VIP2 in comparison to the features of VIP [13] :Changes in VIP2 value VIP2 (VIP) expected gainacceptance 12 % (∼ 1 %) 12increase current 100 A (40 A) > 2reduced length 3 cm (8.8 cm ) 1/3total linear factor 8energy resolution 170 eV (320 eV) @ 8 keV 4reduced active area 6 cm 2 (114 cm 2) 20better shielding and veto 5-10higher SDD efficiency 1/2background reduction 200 - 400overall improvement > 1202. VIP-2 ExperimentThe VIP experiment used a similar method to the Ramberg-Snow experiment, and the samedefinition of the parameter to represent the probability that the PEP is violated for a directcomparison of the experimental results. An improvement in sensitivity was achieved firstly byXIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015) IOP PublishingJournal of Physics: Conference Series 718 (2016) 042055 doi:10.1088/1742-6596/718/4/0420552performing the experiment in the low radioactivity laboratory at LNGS, which has the advantageof the excellent shielding against cosmic rays. Secondly the application of Charge Coupled Device(CCD) as the X-ray detector with a typical energy resolution of 320 eV at 8 keV, increased theprecision in the definition of the region of interest to search for anomalous X-rays. The VIPexperiment set a limit for the probability of the PEP violation to be 4.7 ×10−29 [9, 10].By introducing new X-ray detectors and an active shielding, as listed in the Table 1, theVIP-2 experiment expects to further improve the sensitivity by two orders of magnitude. Thedetectors and the setup of the VIP-2 experiment are introduced by more detail in [11] from thisconference proceedings and in [12, 13],3. Status of preparationFrom 2014 to 2015, we finished the production of 32 pieces of veto detectors made of plasticscintillators coupled to Silicon PhotoMmultipliers(SiPM). The preamplifiers for the SiPMsdeveloped by the Stefan-Meyer-Institut (SMI) in Vienna, were fine tuned and with the vetodetectors we took background data inside the laboratory. The six SDD elements with a totalactive area of 6 cm2 were mounted inside the vacuum chamber and cooled down to 110 K, andwe successfully took calibration data using an Fe-55 source. All the SDDs were performingaccording to expectation with an energy resolution of about 150 eV (FWHM) at 6 keV.Figure 1. Pictures of the detectors inside the setup. Left : a top view of the setup after theSDDs and their preamplifier board were mounted close to the Cu conductor; the bottom layer ofscintillators is also visible in the background; right : same angle of view after the heat insulatorwas wrapped around the SDDs, and the side layer of scintillators were mounted.We define the trigger for data taking by either an event at any SDD or a coincidence betweentwo layers of the veto detector. The trigger logic was implemented using the NIM standardmodules and a VME-based data acquisition system was customized. From the cosmic ray eventsthat produce coincidences between the veto scintillators and the SDDs, we confirmed the timecorrelation whose spread is characterized by the drift time of the SDD of less than 1 µs. TheSDD spectra and the timing correlation plots are shown in [11] of this conference proceedings.To make sure the heat from the Cu conductor when the electric current is applied does notaffect the silicon detectors nearby, we monitored the temperatures of the setup while applyingXIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015) IOP PublishingJournal of Physics: Conference Series 718 (2016) 042055 doi:10.1088/1742-6596/718/4/0420553an electric current up to 80 Ampere. A water chiller with cooling capacity less than 900 W wasconfirmed to be sufficient to keep the Cu at the room temperature level.The series of tests for the detectors, the trigger logic and the slow control/monitors haveconfirmed that the expected performances of the apparatus, as listed in Table 1, were reached.In November 2015, we transported the full setup from Vienna to the VIP-2 experiment site inGran Sasso. We assembled the cryogenic system and the readout logic as shown in Fig. 2 andstarted the test run.Figure 2. A picture of the VIP-2 setup in the barrack at LNGS as in November 2015.As an important step to confirm the operation of the SDDs after the transportation, we tookcalibration data by shining 22 keV X-rays on Zr and Ti foils placed near the SDDs. The spectraobtained are shown in Fig. 3, where all SDDs were in working condition and a preliminaryanalysis showed that the energy resolution is compatible to the one obtained in the tests in theSMI laboratory.4. Summary and perspectivesWe are searching for possible violation of the Pauli exclusion principle for electrons by improvingthe method originally proposed by Ramberg and Snow. The application of high resolution X-raydetectors with timing capability is the key factor to improve the sensitivity.In year 2015, we finished the productions of all the detectors and the apparatus of the VIP-2experiment, and transported the whole setup to LNGS. From the test run in December 2015,the detectors showed same performance as confirmed in previous tests.We started a data taking of about 3 years with the aim to either improve by two orders ofmagnitude the probability of the PEP violation by electrons, or to find a small violation.XIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015) IOP PublishingJournal of Physics: Conference Series 718 (2016) 042055 doi:10.1088/1742-6596/718/4/0420554Energy [eV]4000 6000 8000 10000 12000 14000 16000 18000 200000100200300400500600700800 Ti KaZr KaCu KaEnergy [eV]4000 6000 8000 10000 12000 14000 16000 18000 2000002004006008001000120014001600Energy [eV]4000 6000 8000 10000 12000 14000 16000 18000 20000020040060080010001200140016001800Ti Ka Cu KaZr KaZr KaCu KaTi KaEnergy [eV]4000 6000 8000 10000 12000 14000 16000 18000 2000002004006008001000count / 64 eVEnergy [eV]4000 6000 8000 10000 12000 14000 16000 18000 2000002004006008001000120014001600Energy [eV]4000 6000 8000 10000 12000 14000 16000 18000 200000100200300400500600Ti Ka Ti Ka Ti KaCu KaCu KaCu KaZr Ka Zr Ka Zr Kacount / 64 eVFigure 3. Energy spectra of SDDs from a calibration run in the VIP barrack at LNGS. Therelative intensity of the Cu Ka varies due to geometrical reason.AcknowledgementsWe thank H. Schneider, L. Stohwasser, and D. Stu¨ckler from Stefan-Meyer-Institut for theirfundamental contribution in designing and building the VIP2 setup. We thank the veryimportant assistance of the INFN-LNGS laboratory staff during all phases of preparation,installation and data taking as well as the support from the HadronPhysics FP6(506078),HadronPhysics2 FP7 (227431), HadronPhysics3 (283286) projects and the EU COST 1006Action is gratefully acknowledged. Especially we thank the Austrian Science Foundation (FWF)which supports the VIP2 project with the grant P25529-N20, and we thank the support fromthe EU COST Action MP1006, Fundamental Problems in Quantum Physics, and from CentroFermi (“Problemi aperti nella meccania quantistica”project). Furthermore, this paper was madepossible through the support of a grant from the John Templeton Foundation (ID 581589). Theopinions expressed in this publication are those of the authors and do not necessarily reflect theviews of the John Templeton Foundation.References[1] Messiah A.M.L. 1962 Quantum Mechanics, Vol. II, North-Holland, Amsterdam, p. 595[2] Messiah A.M.L and Greenberg O.W 1964 Physics Review 136 B248[3] Elliott S R et al 2012 Found. Phys. 42 1015[4] Greenberg O.W 2000 AIP Conf. Proc. 545 113[5] Ramberg E and Snow G A 1990 Physics Letters B 238 438[6] Curceanu C et al 2013 INFN preprint INFN-13-21/LNF[7] Prange R and Girvin S M The Quantum Hall Effect, Springer-Verlag, New York[8] Stern A 2008 Annals of Physics 323 204[9] Bartalucci S et al 2006 Physics Letters B 641 18[10] Bartalucci S et al 2009 Found. Phys. 40 765[11] Pichler A et al in this Conference Proceedings[12] Shi H et al 2015 Physics Procedia p.522[13] Marton J et al 2013 Journal of Physics: Conference Series 447 012070XIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015) IOP PublishingJournal of Physics: Conference Series 718 (2016) 042055 doi:10.1088/1742-6596/718/4/0420555

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

International audienceThe VIP (Violation of Pauli exclusion principle) experiment and its follow-up experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays from Cu atomic states that are prohibited by the Pauli Exclusion Principle (PEP). The candidate events, if they exist, will originate from the transition of a 2p orbit electron to the ground state which is already occupied by two electrons. The present limit on the probability for PEP violation for electron is 4.7 ×10-29 set by the VIP experiment. With upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by 2 orders of magnitude

Bragadireanu, A.M.

de Paolis, L.

Di Matteo, Sergio

d'Ufflzi, A.

Egger, J.-P.

Vidal, A.R.

Sirghi, D.L.

Doce, O.V.

HAL-Rennes 1

H Shi

S Bartalucci

S Bertolucci

C Berucci

A M Bragadireanu

M Cargnelli

A Clozza

C Curceanu

L De Paolis

S Di Matteo

A d’Ufflzi

J-P Egger

C Guaraldo

M Iliescu

T Ishiwatari

J Marton

M Laubenstein

E Milotti

D Pietreanu

K Piscicchia

T Ponta

A Romero Vidal

E Sbardella

A Scordo

D L Sirghi

F Sirghi

L Sperandio

O Vazquez Doce

E Widmann

J Zmeskal

Crossref

Journal of Physics Conference Series

HAL: Hyper Article en Ligne

The VIP (Violation of Pauli exclusion principle) experiment and its follow-up experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays from Cu atomic states that are prohibited by the Pauli Exclusion Principle (PEP). The candidate events, if they exist, will originate from the transition of a $2p$ orbit electron to the ground state which is already occupied by two electrons. The present limit on the probability for PEP violation for electron is 4.7 $\times10^{-29}$ set by the VIP experiment. With upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by two orders of magnitude.The VIP (Violation of Pauli exclusion principle) experiment and its follow-up experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays from Cu atomic states that are prohibited by the Pauli Exclusion Principle (PEP). The candidate events, if they exist, will originate from the transition of a 2p orbit electron to the ground state which is already occupied by two electrons. The present limit on the probability for PEP violation for electron is 4.7 ×10(–)(29) set by the VIP experiment. With upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by 2 orders of magnitude.The VIP (Violation of Pauli exclusion principle) experiment and its follow-up experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays from Cu atomic states that are prohibited by the Pauli Exclusion Principle (PEP). The candidate events, if they exist, will originate from the transition of a $2p$ orbit electron to the ground state which is already occupied by two electrons. The present limit on the probability for PEP violation for electron is 4.7 $\times10^{-29}$ set by the VIP experiment. With upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by two orders of magnitude

Romero Vidal, A.

Vazquez Doce, O.

CERN Document Server

Searches for the Violation of Pauli Exclusion Principle at LNGS in VIP(-2) experiment

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Searches for the Violation of Pauli Exclusion Principle at LNGS in
  VIP(-2) experiment

Searches for the Violation of Pauli Exclusion Principle at LNGS in VIP(-2) experiment

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