arXiv subjects

F. Sirghi

Publications and source records attributed to F. Sirghi.

At least 55 records · Page 3Linked to original sources

arXiv2017

Test of the Pauli Exclusion Principle in the VIP-2 underground experiment

The validity of the Pauli Exclusion Principle, a building block of Quantum Mechanics, is tested for electrons. The VIP (VIolation of Pauli exclusion principle) and its follow-up VIP-2 experiments at the Laboratori Nazionali del Gran Sasso search for x-rays from copper atomic transition that are prohibited by the Pauli Exclusion Principle. The candidate events, if they exist, 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 Pauli Exclusion Principle violation for electrons set by the VIP experiment is 4.7 $\times$ 10 $^{-29}$. We report a first result from the VIP-2 experiment improving on the VIP limit, that solidifies the final goal to achieve a two order of magnitude gain in the long run.

quant-ph↗

arXiv2017

VIP2 at Gran Sasso - Test of the validity of the spin statistics theorem for electrons with X-ray spectroscopy

In the VIP2 (VIolation of the Pauli Exlusion Principle) 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.

physics.ins-det↗

arXiv2017

VOXES, a new high resolution X-ray spectrometer for low yield measurements with diffused sources

The VOXES project's goal is to realize the first prototype of a high resolution and high precision X-ray spectrometer for diffused sources, using Highly Annealed Pyrolitic Graphite (HAPG) crystals combined with precision position detectors. The aim is to deliver a cost effective and easy to handle system having an energy resolution at the level of few eV for X-ray energies from about 2 keV up to tens of keV. There are many applications of the proposed spectrometer, going from fundamental physics (precision measurements of exotic atoms at DA$Φ$NE collider and J-PARC, precision measurement of the $K^-$ mass solving the existing puzzle, quantum mechanics tests) to synchrotron radiation and applications (X-FEL), astronomy, medicine and industry. Here, the basic concept of such a spectrometer and the first results from a measurement of the characteristic Cu $K_{α1}$ and $K_{α2}$ X-ray lines are presented.

physics.ins-det↗

arXiv2017

Measurement of the running of the fine structure constant below 1 GeV with the KLOE Detector

We have measured the running of the effective QED coupling constant $α(s)$ in the time-like region $0.6<\sqrt s< 0.975$ GeV with the KLOE detector at DA$Φ$NE using the Initial State Radiation process $e^+e^-\toμ^+ μ^-γ$. It represents the first measurement of the running of $α(s)$ in this energy region. Our results show a more than 5$σ$ significance of the hadronic contribution to the running of $α(s)$, which is the strongest direct evidence both in time- and space-like regions achieved in a single measurement. By using the $e^+e^-\toπ^+π^-$ cross section measured by KLOE, the real and imaginary part of the shift $Δα(s)$ has been extracted. By a fit of the real part of $Δα(s)$ and assuming the lepton universality the branching ratio $BR(ω\toμ^+μ^-) = (6.6\pm1.4_{stat}\pm1.7_{syst})\cdot 10^{-5} $ has been determined.

hep-ex↗

arXiv2017

Underground tests of quantum mechanics. Whispers in the cosmic silence?

By performing X-rays measurements in the "cosmic silence" of the underground laboratory of Gran Sasso, LNGS-INFN, we test a basic principle of quantum mechanics: the Pauli Exclusion Principle (PEP), for electrons. We present the achieved results of the VIP experiment and the ongoing VIP2 measurement aiming to gain two orders of magnitude improvement in testing PEP. We also use a similar experimental technique to search for radiation (X and gamma) predicted by continuous spontaneous localization models, which aim to solve the "measurement problem".

quant-ph↗

arXiv2017

VIP-2 at LNGS: An experiment on the validity of the Pauli Exclusion Principle for electrons

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 10E-31. We show preliminary experimental results and discuss implications of a possible violation.

quant-ph↗

arXiv2016

Measurement of the $ϕ\to π^0 e^+e^-$ transition form factor with the KLOE detector

A measurement of the vector to pseudoscalar conversion decay $ϕ\to π^0 e^+e^-$ with the KLOE experiment is presented. A sample of $\sim 9500$ signal events was selected from a data set of 1.7 fb$^{-1}$ of $e^+e^-$ collisions at $\sqrt{s} \sim m_ϕ$ collected at the DA$Φ$NE $e^+e^-$ collider. These events were used to obtain the first measurement of the transition form factor $| F_{ϕπ^0}(q^2) |$ and a new measurement of the branching ratio of the decay: $\rm{BR}\,(ϕ\to π^0 e^+e^-) = (\,1.35 \pm 0.05^{\,\,+0.05}_{\,\,-0.10}\,) \times 10 ^{-5}$. The result improves significantly on previous measurements and is in agreement with theoretical predictions.

hep-ex↗

arXiv2016

$K$-series X-ray yield measurement of kaonic hydrogen atoms in a gaseous target

We measured the $K$-series X-rays of the $K^{-}p$ exotic atom in the SIDDHARTA experiment with a gaseous hydrogen target of 1.3 g/l, which is about 15 times the $ρ_{\rm STP}$ of hydrogen gas. At this density, the absolute yields of kaonic X-rays, when a negatively charged kaon stopped inside the target, were determined to be 0.012$^{+0.004}_{-0.003}$ for $K_α$ and 0.043$^{+0.012}_{-0.011}$ for all the $K$-series transitions $K_{tot}$. These results, together with the KEK E228 experiment results, confirm for the first time a target density dependence of the yield predicted by the cascade models, and provide valuable information to refine the parameters used in the cascade models for the kaonic atoms.

nucl-ex↗

arXiv2016

Strong interaction studies with kaonic atoms

The strong interaction of antikaons with nucleons and nuclei in the low-energy regime represents an active research field connected intrinsically with few-body physics. There are important open questions like the question of antikaon nuclear bound states. A unique and rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions in low-lying states of light kaonic atoms like kaonic hydrogen isotopes. In the SIDDHARTA experiment at the electron-positron collider DAFNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound kaonic hydrogen atom leading to a hadronic shift and a hadronic broadening of the 1s state. The SIDDHARTA result triggered new theoretical work which achieved major progress in the understanding of the low-energy strong interaction with strangeness. Antikaon-nucleon scattering lengths have been calculated constrained by the SIDDHARTA data on kaonic hydrogen. For the extraction of the isospin-dependent scattering lengths a measurement of the hadronic shift and width of kaonic deuterium is necessary. Therefore, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2). Many improvements in the experimental setup will allow to measure kaonic deuterium which is challenging due to the anticipated low X-ray yield. Especially important are the data on the X-ray yields of kaonic deuterium extracted from a exploratory experiment within SIDDHARTA.

nucl-ex↗

arXiv2016

Limit on the production of a new vector boson in $\mathrm{e^+ e^-}\rightarrow {\rm U}γ$, U$\rightarrow π^+π^-$ with the KLOE experiment

The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in ${\rm e^+ e^-}\rightarrow {\rm U}γ$, U$\rightarrow π^+π^-$ based on 28 million $\mathrm{e^+ e^-} \rightarrow π^+ π^-γ$ events collected at DA$Φ$NE by the KLOE experiment. The $π^+ π^-$ production by initial-state radiation compensates for a loss of sensitivity of previous KLOE ${\rm U} \rightarrow \mathrm{e^+ e^-}$, $μ^+μ^-$ searches due to the small branching ratios in the $ρ-ω$ resonance region. We found no evidence for a signal and set a limit at 90\% CL on the mixing strength between the photon and the dark photon, $\varepsilon^2$, in the U mass range between $527$ and $987$~MeV. Above 700 MeV this new limit is more stringent than previous ones.

hep-ex↗

arXiv2016

Structure near $K^-$+$p$+$p$ threshold in the in-flight $^3$He$(K^-,Λp)n$ reaction

To search for an S= -1 di-baryonic state which decays to $Λp$, the $ {\rm{}^3He}(K^-,Λp)n_{missing}$ reaction was studied at 1.0 GeV/$c$. Unobserved neutrons were kinematically identified from the missing mass $M_X$ of the $ {\rm{}^3He}(K^-,Λp)X$ reaction in order to have a large acceptance for the $Λpn$ final state. The observed $Λp n$ events, distributed widely over the kinematically allowed region of the Dalitz plot, establish that the major component comes from a three nucleon absorption process. A concentration of events at a specific neutron kinetic energy was observed in a region of low momentum transfer to the $Λp$. To account for the observed peak structure, the simplest S-wave pole was assumed to exist in the reaction channel, having Breit-Wigner form in energy and with a Gaussian form-factor. A minimum $χ^2$ method was applied to deduce its mass $M_X\ =$ 2355 $ ^{+ 6}_{ - 8}$ (stat.) $ \pm 12$ (syst.) MeV/c$^2$, and decay-width $Γ_X\ = $ 110 $ ^{+ 19}_{ - 17}$ (stat.) $ \pm 27$ (syst.) MeV/c$^2$, respectively. The form factor parameter $Q_X \sim$ 400 MeV/$c$ implies that the range of interaction is about 0.5

nucl-ex↗

arXiv2016

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

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.

physics.ins-det↗

arXiv2016

Application of photon detectors in the VIP2 experiment to test the Pauli Exclusion Principle

The Pauli Exclusion Principle (PEP) was introduced by the austrian physicist Wolfgang Pauli in 1925. Since then, several experiments have checked its validity. From 2006 until 2010, the VIP (VIolation of the Pauli Principle) experiment took data at the LNGS underground laboratory to test the PEP. This experiment looked for electronic 2p to 1s transitions in copper, where 2 electrons are in the 1s state before the transition happens. These transitions violate the PEP. The lack of detection of X-ray photons coming from these transitions resulted in a preliminary upper limit for the violation of the PEP of $4.7 \times 10^{-29}$. Currently, the successor experiment VIP2 is under preparation. The main improvements are, on one side, the use of Silicon Drift Detectors (SDDs) as X-ray photon detectors. On the other side an active shielding is implemented, which consists of plastic scintillator bars read by Silicon Photomultipliers (SiPMs). The employment of these detectors will improve the upper limit for the violation of the PEP by around 2 orders of magnitude.

physics.ins-det↗

arXiv2016

Precision measurement of the $η\toπ^+π^-π^0$ Dalitz plot distribution with the KLOE detector

Using $1.6$ fb$^{-1}$ of $e^+ e^-\toϕ\toηγ$ data collected with the KLOE detector at DA$Φ$NE, the Dalitz plot distribution for the $η\to π^+ π^- π^0$ decay is studied with the world's largest sample of $\sim 4.7 \cdot 10^6$ events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables $X$ and $Y$. The experiment is sensitive to all charge conjugation conserving terms of the expansion, including a $gX^2Y$ term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements.

hep-ex↗

arXiv2016

Spontaneously emitted X-rays: an experimental signature of the dynamical reduction models

We present the idea of searching for X-rays as a signature of the mechanism inducing the spontaneous collapse of the wave function. Such a signal is predicted by the continuous spontaneous localization theories, which are solving the "measurement problem" by modifying the Schrodinger equation. We will show some encouraging preliminary results and discuss future plans and strategy.

quant-ph↗

arXiv2016

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

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.

physics.ins-det↗

arXiv2016

Precision X-ray spectroscopy of kaonic atoms as a probe of low-energy kaon-nucleus interaction

In the exotic atoms where one atomic $1s$ electron is replaced by a $K^{-}$, the strong interaction between the $K^{-}$ and the nucleus introduces an energy shift and broadening of the low-lying kaonic atomic levels which are determined by only the electromagnetic interaction. By performing X-ray spectroscopy for Z=1,2 kaonic atoms, the SIDDHARTA experiment determined with high precision the shift and width for the $1s$ state of $K^{-}p$ and the $2p$ state of kaonic helium-3 and kaonic helium-4. These results provided unique information of the kaon-nucleus interaction in the low energy limit.

nucl-ex↗

arXiv2015

Shedding New Light on Kaon-Nucleon/Nuclei Interaction and Its Astrophysical Implications with the AMADEUS Experiment at DAFNE

The AMADEUS experiment deals with the investigation of the low-energy kaon-nuclei hadronic interaction at the DAΦNE collider at LNF-INFN, which is fundamental to respond longstanding questions in the non-perturbative QCD strangeness sector. The antikaon-nucleon potential is investigated searching for signals from possible bound kaonic clusters, which would open the possibility for the formation of cold dense baryonic matter. The confirmation of this scenario may imply a fundamental role of strangeness in astrophysics. AMADEUS step 0 consisted in the reanalysis of 2004/2005 KLOE dataset, exploiting K- absorptions in H, 4He, 9Be and 12C in the setup materials. In this paper, together with a review on the multi-nucleon K- absorption and the particle identification procedure, the first results on the Σ0-p channel will be presented including a statistical analysis on the possible accomodation of a deeply bound state

nucl-ex↗