Catalina Curceanu LNF – INFN On behalf of VIP Collaboration Gr 3 – Roma, 20 Marzo 2012

E ulteriori risultati nonche’ discussioni coi referees

VIP is an experiment to test the Pauli Exclusion Principle (PEP) for electrons in a clean environment (LNGS).

n=2 n=1 Normal 2p –>1s transition Energy 8.05 keV 2p –>1s transition violating Pauli principle Energy 7.7 keV Search for anomalous X-ray transitions when bringing “new” electrons Experimental method: n=2 n=1 Messiah Greenberg superselection rule

Search for anomalous electronic transitions in Cu induced by a circulating current (“new” external electrons, which interact with the valence electrons), namely transition from 2p to 1s already filled by 2 electrons The pre-VIP experiment limit: Ramberg and Snow (RS) Phys. Lett. B238 (1990) 438

The parameter  Ignatiev & Kuzmin model creation and destruction operators connect 3 states connect 3 states - the vacuum state - the vacuum state - the single occupancy state - the single occupancy state - the non-standard double occupancy state - the non-standard double occupancy state 0000 1111 2222 through the following relations: The parameter  quantifies the degree of violation in the transition. It is very small and for   0 we can have the Fermi -. It is very small and for   0 we can have the Fermi - Dirac statistic again.  1   2222

this  can be simply related to the q parameter of the quon theory of Greenberg and Mohapatra quon algebra is a sort of weighted average between fermion and boson algebra: or also

The VIP experiment VIP is a much improved version of the previous (RS) experiment: 1.sensitive, large-area, X-ray detectors: CCD di DEAR (non-triggerable…) 2.clean, low-background experimental area (LNGS) 3.large “electron reservoir”

The VIP setup

Cu Target

Final setup has been used for preliminary measurements at the LNF-Frascati laboratory – 21 nov dec. 2005

subtracted spectra (“current” - “no current”) Phys. Lett. B 641 (2006) 18

VIP setup at LNGS

VIP limit at LNGS (Ph D thesis Laura Sperandio – Tor Vergata) We have thus improved the limit obtained by Ramberg & Snow by a factor  400 We have thus improved the limit obtained by Ramberg & Snow by a factor  400 (Foundation of Physics 41 (2011) 282)

Ad oggi: VIP upgrade

Drawbacks of VIP: -Reused an already done setup (DEAR experiment) – limitations in many aspects: signal and background - No timing (trigger) capabilities - Limited energy (efficiency) range (30 microns) VIP-upgrade:  Use new detectors – triggerable SDD  300 microns – more efficient in a broader energy range  Design a new setup – much more compact; higher acceptance (present one 2.8%) and lower background  guadagnare fattore 100!

Mini-Proceedings ECT*: Speakable in quantum mechanics: atomic, nuclear and subnuclear physics tests Authors: C. Curceanu, J. Marton, E. Milotti arXiv: v1 CERN Courier: Quantum mechanics in the 21st century

-VIP physics of interest!!! - the only experiment checking PEP for elementary particle (electron) with a proper method (see VIP report) – superselection rule of Messiah - Greenberg -Because we think we can improve the limit by 2 orders of magnitude (new detectors – triggerable, more compact geometry – bigger acceptance and smallr background)

it is very important to check PEP for all particle species and for elementary particles as electrons. An eminent theorist – A. Balachandran – writes (private communication): 1) It is extremely important to look for Pauli principle violations in a variety of systems which includes nucleons just as CP violation is looked for both in processes which include strongly interacting particles and in those which involve leptons and QED processes. It is only then that a coherent theory of such processes can be evolved. 2) Theoretical calculations for processes involving nucleons, and worse still nuclei, are subject to many errors. Such errors may not be tolerable when one is studying a very small effect like the Pauli principle violation. Processes involving electron are to be preferred from this point of view. Nucleons are complex and even now, there are many unresolved issues, e.g., about their quark content. In contrast, electrons are very well understood and it is much easier to isolate novel effects like Pauli principle violation in electronic processes.

Theories of Violation of Statistics O.W. Greenberg: AIP Conf.Proc.545: ,2004 “Possible external motivations for violation of statistics include: (a) violation of CPT, (b) violation of locality, (c) violation of Lorentz invariance, (d) extra space dimensions, (e) discrete space and/or time and (f) noncommutative spacetime. Of these (a) seems unlikely because the quon theory which obeys CPT allows violations, (b) seems likely because if locality is satisfied we can prove the spin-statistics connection and there will be no violations, (c), (d), (e) and (f) seem possible………….. Hopefully either violation will be found experimentally or our theoretical efforts will lead to understanding of why only bose and fermi statistics occur in Nature.”

Duck and Sudarshan also suggest that a violation might be connected with modern physical theories: (Duck and E. C. G. Sudarshan: Towards an understanding of the spin-statistics theorem, Am. J. Phys, 66 (1998) 284): “More recently … membrane theorists have been speculating on a large compactification radius for one of their eleven dimensions, which could give a ratio (for PEP violation) of ”

SDD detectors (usati in SIDDHARTA)

Test measurements at LNGS and MCarlo simulations -> metodo funziona (risultati nel Report) calcolo gain factor

Material selection - PIXE Analysis of Al

Gain factors

Signal

Background

Abbiamo incluso (stando alla richiesta dei referee) una nitrogen flow box (riduzione fondi) e fatto dei test su prototipo target

Inside view into the VIP-2 vacuum chamber

The VIP-2 vacuum chamber

The VIP-2 target – detector – veto counter setup

The VIP-2 target

The VIP-2 target – detector configuration

the cooled Cu-target stripes

Attivita’: - preparazione sito LNGS e interazione con: Direttore LNGS, servizi supporto esperimenti e sicurezze - costruzione setup (vacuum chamber; target, cooling system, veto) - piano di lavoro: in linea con le Milestones - richiesta sblocco SJ del cryotiger (discussione con referee)

We then expect either to find a small violation or to be able to bound the probability that PEP is violated by electrons pushing it from about 4· to (this limit is obtained taking into account a data taking period similar to that of VIP, i.e. about 3-4 years). Explore other type of physics – quantum mechanics (collapse models predictions)

Workshop: Open Problems in Quantum Mechanics Organizers: P. Zanghi’, A. Bassi, C. Curceanu, B. Vacchini LNF-INFN from 20 to 22 June 2012

Veto-counter setup scintillator bar – SiPMs with pre-amplifier board

Condenser for target and SDDs