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V. Antonelli

Publications and source records attributed to V. Antonelli.

At least 37 records · Page 2Linked to original sources

Neutrino oscillations and Lorentz Invariance Violation in a Finslerian Geometrical model

Neutrino oscillations are one of the first evidences of physics beyond the Standard Model (SM). Since Lorentz Invariance is a fundamental symmetry of the SM, recently also neutrino physics has been explored to verify the eventual modification of this symmetry and its potential magnitude. In this work we study the consequences of the introduction of Lorentz Invariance Violation (LIV) in the high energy neutrinos propagation and evaluate the impact of this eventual violation on the oscillation predictions. An effective theory explaining these physical effects is introduced via Modified Dispersion Relations. This approach, originally introduced by Coleman and Glashow, corresponds in our model to a modification of the special relativity geometry. Moreover, the generalization of this perspective leads to the introduction of a maximum attainable velocity which is specific of the particle. This can be formalized in Finsler geometry, a more general theory of space-time. In the present paper the impact of this kind of LIV on neutrino phenomenology is studied, in particular by analyzing the corrections introduced in neutrino oscillation probabilities for different values of neutrino energies and baselines of experimental interest. The possibility of further improving the present constraints on CPT-even LIV coefficients by means of our analysis is also discussed.

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Nanoseconds Timing System Based on IEEE 1588 FPGA Implementation

Clock synchronization procedures are mandatory in most physical experiments where event fragments are readout by spatially dislocated sensors and must be glued together to reconstruct key parameters (e.g. energy, interaction vertex etc.) of the process under investigation. These distributed data readout topologies rely on an accurate time information available at the frontend, where raw data are acquired and tagged with a precise timestamp prior to data buffering and central data collecting. This makes the network complexity and latency, between frontend and backend electronics, negligible within upper bounds imposed by the frontend data buffer capability. The proposed research work describes an FPGA implementation of IEEE 1588 Precision Time Protocol (PTP) that exploits the CERN Timing, Trigger and Control (TTC) system as a multicast messaging physical and data link layer. The hardware implementation extends the clock synchronization to the nanoseconds range, overcoming the typical accuracy limitations inferred by computers Ethernet based Local Area Network (LAN). Establishing a reliable communication between master and timing receiver nodes is essential in a message-based synchronization system. In the backend electronics, the serial data streams synchronization with the global clock domain is guaranteed by an hardware-based finite state machine that scans the bit period using a variable delay chain and finds the optimal sampling point. The validity of the proposed timing system has been proved in point-to-point data links as well as in star topology configurations over standard CAT-5e cables. The results achieved together with weaknesses and possible improvements are hereby detailed.

cs.NI↗

Charge reconstruction in large-area photomultipliers

Large-area PhotoMultiplier Tubes (PMT) allow to efficiently instrument Liquid Scintillator (LS) neutrino detectors, where large target masses are pivotal to compensate for neutrinos' extremely elusive nature. Depending on the detector light yield, several scintillation photons stemming from the same neutrino interaction are likely to hit a single PMT in a few tens/hundreds of nanoseconds, resulting in several photoelectrons (PEs) to pile-up at the PMT anode. In such scenario, the signal generated by each PE is entangled to the others, and an accurate PMT charge reconstruction becomes challenging. This manuscript describes an experimental method able to address the PMT charge reconstruction in the case of large PE pile-up, providing an unbiased charge estimator at the permille level up to 15 detected PEs. The method is based on a signal filtering technique (Wiener filter) which suppresses the noise due to both PMT and readout electronics, and on a Fourier-based deconvolution able to minimize the influence of signal distortions ---such as an overshoot. The analysis of simulated PMT waveforms shows that the slope of a linear regression modeling the relation between reconstructed and true charge values improves from $0.769 \pm 0.001$ (without deconvolution) to $0.989 \pm 0.001$ (with deconvolution), where unitary slope implies perfect reconstruction. A C++ implementation of the charge reconstruction algorithm is available online at http://www.fe.infn.it/CRA .

physics.ins-det↗

Status and potentialities of the JUNO experiment

One of the main open issues of neutrino physics is the determination of the mass hierarchy, discriminating between the two possible ordering of the mass eigenvalues, known as Normal and Inverted Hierarchies. The solution of this puzzle would have a significant impact both on elementary particle physics and astrophysics. A possible way to investigate the problem is the study, with medium baseline reactor antineutrinos, of the mass dependent corrections to inverse $β$ decays. This is the idea pursued by JUNO, a multipurpose underground liquid scintillator experiment that will start data taking in very few years from now. The main characteristics and the status of the experiment are discussed here, together with its rich physics program. We focus in particular on the potentiality for mass hierarchy determination, the main goal of the experiment, on the oscillation parameters accurate measurements and on the supernova and solar neutrinos and geoneutrino studies.

hep-ph↗

JUNO Conceptual Design Report

The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine the neutrino mass hierarchy using an underground liquid scintillator detector. It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants in Guangdong, China. The experimental hall, spanning more than 50 meters, is under a granite mountain of over 700 m overburden. Within six years of running, the detection of reactor antineutrinos can resolve the neutrino mass hierarchy at a confidence level of 3-4$σ$, and determine neutrino oscillation parameters $\sin^2θ_{12}$, $Δm^2_{21}$, and $|Δm^2_{ee}|$ to an accuracy of better than 1%. The JUNO detector can be also used to study terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard Model. The central detector contains 20,000 tons liquid scintillator with an acrylic sphere of 35 m in diameter. $\sim$17,000 508-mm diameter PMTs with high quantum efficiency provide $\sim$75% optical coverage. The current choice of the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of detected photoelectrons per MeV is larger than 1,100 and the energy resolution is expected to be 3% at 1 MeV. The calibration system is designed to deploy multiple sources to cover the entire energy range of reactor antineutrinos, and to achieve a full-volume position coverage inside the detector. The veto system is used for muon detection, muon induced background study and reduction. It consists of a Water Cherenkov detector and a Top Tracker system. The readout system, the detector control system and the offline system insure efficient and stable data acquisition and processing.

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Solar Neutrinos

The study of solar neutrinos has given since ever a fundamental contribution both to astroparticle and to elementary particle physics, offering an ideal test of solar models and offering at the same time relevant indications on the fundamental interactions among particles. After reviewing the striking results of the last two decades, which were determinant to solve the long standing solar neutrino puzzle and refine the Standard Solar Model, we focus our attention on the more recent results in this field and on the experiments presently running or planned for the near future. The main focus at the moment is to improve the knowledge of the mass and mixing pattern and especially to study in detail the lowest energy part of the spectrum, which represents most of solar neutrino spectrum but is still a partially unexplored realm. We discuss this research project and the way in which present and future experiments could contribute to make the theoretical framemork more complete and stable, understanding the origin of some "anomalies" that seem to emerge from the data and contributing to answer some present questions, like the exact mechanism of the vacuum to matter transition and the solution of the so called solar metallicity problem.

hep-ex↗

Tests of the Standard Model with Low-Energy Neutrino Beams

We discuss the possibility of using future high--intensity low--energy neutrino beams for precision tests of the Standard Model. In particular we consider the determination of the electroweak mixing angle from elastic and quasi--elastic neutrino--nucleon scattering at a superbeam or $β$--beam.

hep-ph↗

Statistically improved Analysis of Neutrino Oscillation Data with the latest KamLAND result

We present an updated analysis of all available solar and reactor neutrino data, emphasizing in particular the totality of the KamLAND (314d live time) results and including for the first time the solar $SNO$ (391d live time, phase II NaCl-enhanced) spectrum data. As a novelty of the statistical analysis, we study the variability of the KamLand results with respect the use of diverse statistics. A new statistic, not used before is proposed. Moreover, in the analysis of the SNO spectrum a novel technique is used in order to include full correlated errors among bins. Combining all data, we obtain the following best-fit parameters: we determine individual neutrino mixing parameters and their errors $ Δm^2= 8.2\pm 0.08\times 10^{-5} \eV^2,\quad \tan^2θ= 0.50^{+0.12}_{-0.07}.$ The impact of these results is discussed. We also estimate the individual elements of the neutrino mass matrix. In the framework of three neutrino oscillations we obtain the mass matrix: \begin{eqnarray}M&=& eV \pmatrix{1.0+ 4.0\pm 3.2 10^{-5}& 4.2\pm 3.2 10^{-5} &-13.5\pm 14.0 10^{-5} \cr 4.2\pm 3.2 10^{-5}& 1.0+4.3\pm 3.5 10^{-5} &-13.5\pm 14.5 10^{-5} \cr 13.5\pm 14.0 10^{-5}& -13.5\pm 14.5 10^{-5} &1.0+100.0\pm 30.0\ 10^{-5}}.\end{eqnarray}

hep-ph↗

Analysis of Neutrino oscillation data with the recent KamLAND results

We present an updated analysis of all available solar and reactor neutrino data, emphasizing in particular the totality of the KamLAND results and including the SNO phase III spectrum data. In a two active-neutrino framework, we determine the solutions in the $Δm_{\odot}^2, \tan^2θ_{\odot}$ parameter space compatible with experimental data. Combining all data, we obtain the following best-fit parameters: $Δm_{\odot}^2 =8.17*10^-5$, $\tan^2θ_{\odot}=0.40$

hep-ph↗

Neutrino transition magnetic moments and the solar magnetic field on the light of the Kamland evidence

We present here a recopilation of recent results about the possibility of detecting solar electron antineutrinos produced by solar core and convective magnetic fields. These antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. Using the recent Kamland results and assuming a concrete model for antineutrino production by spin-flavor precession in the convective zone based on chaotic magnetic fields,we obtain bounds on the flux of solar antineutrinos, on the average conversion neutrino-antineutrino probability and on intrinsic neutrino magnetic moment. In the most conservative case, $μ\lsim 2.5\times 10^{-11} μ_B$ (95% CL). When studying the effects of a core magnetic field, we find in the weak limit a scaling of the antineutrino probability with respect to the magnetic field profile in the sense that the same probability function can be reproduced by any profile with a suitable peak field value. In this way the solar electron antineutrino spectrum can be unambiguosly predicted. We use this scaling and the negative results indicated by the KamLAND experiment to obtain upper bounds on the solar electron antineutrino flux. We find that, for a wide family of magnetic field profiles in the sun interior, the antineutrino appearance probability is largely determined by the magnetic field intensity but not by its shape. Explicit limits on neutrino transition moments are also obtained consistent with the convective case. These limits are therefore largerly independent of the detailed structure of the magnetic field in the solar interior.

hep-ph↗

The Neutrino mass matrix after Kamland and SNO salt enhanced results

An updated analysis of all available neutrino oscillation evidence in Solar experiments including the latest SNO ES,CC and NC data (254d live time, NaCL enhanced efficiency) is presented. We obtain, for the fraction of active oscillating neutrinos: sin^2alpha=(Φ_{NC}-Φ_{CC})/(Φ_{SSM}-Φ_{CC})=0.94^{+0.0.065}_{-0.060} nearly 20σfrom the pure sterile oscillation case. The fraction of oscillating sterile neutrinos cos^2α\lsim 0.12 (1 sigma CL). At face value, these results might slightly favour the existence of a small sterile oscillating sector. In the framework of two active neutrino oscillations we determine individual neutrino mixing parameters and their errors we obtain Delta m^2= 7.01\pm 0.08 \times 10^{-5} eV^2, tan^2 theta=0.42^{+0.12}_{-0.07}. The main difference with previous analysis is a better resolution in parameter space. In particular the secondary region at larger mass differences (LMAII) is now excluded at 95% CL. The combined analysis of solar and Kamland data concludes that maximal mixing is not favoured at 4-5 sigma. This is not supported by the antineutrino reactor results alone. We estimate the individual elements of the two neutrino mass matrix, writing M^2=m^2 I+M_0^2, we obtain (1 sigma errors): M_0^2=10^{-5} eV^2\pmatrix{ 2.06^{+0.29}_{-0.31} & 3.15^{+0.29}_{-0.35} \cr 3.15^{+0.29}_{-0.35} & 4.60^{+0.56}_{-0.44} }.

hep-ph↗

Neutrino mass parameters from Kamland, SNO and other solar evidence

An updated analysis of all available neutrino oscillation evidence in Reactor (Kamland, first 145 days of data) and Solar experiments (SK day and night spectra, global rates from Homestake, SAGE and GALLEX) including the $SNO CC$ and $NC$ data is presented. In the framework of two active neutrino oscillations we determine the allowed regions in neutrino parameter space, we obtain, from the Kamland spectral shape and global signal, the following antineutrino best solution parameters, $ Δm^2_{kl}= 7.7\times 10^{-5} \eV^2, \tan^2θ_{kl}= 0.98.$ The overall effect of the measured observed ratio $R\sim 0.6$ is that the LMA region remains the only one which is still favored. Combining Kamland and Solar data and assuming CPT invariance, i.e. the same mass matrix for neutrino and antineutrinos, we obtain the following antineutrino best solution parameters (LMAI solution), $ Δm^2= 7.1\times 10^{-5} \eV^2,\tan^2θ= 0.47.$ A second solution (LMAII) appears for values $ Δm^2= 1.5\times 10^{-4} \eV^2, \tan^2θ= 0.48.$ We determine additionally individual neutrino mixing parameters and their errors from fits to marginal likelihood distributions, the values are compatible with previous results. In both methods, $χ^2$ minimization and marginal likelihood, the combined analysis of solar and Kamland data concludes that maximal mixing is not favored at the $\sim 3σ$ level at least.

hep-ph↗

Hamevol1.0: a C++ code for differential equations based on Runge-Kutta algorithm. An application to matter enhanced neutrino oscillation

We present a C++ implementation of a fifth order semi-implicit Runge-Kutta algorithm for solving Ordinary Differential Equations. This algorithm can be used for studying many different problems and in particular it can be applied for computing the evolution of any system whose Hamiltonian is known. We consider in particular the problem of calculating the neutrino oscillation probabilities in presence of matter interactions. The time performance and the accuracy of this implementation is competitive with respect to the other analytical and numerical techniques used in literature. The algorithm design and the salient features of the code are presented and discussed and some explicit examples of code application are given.

cs.CE↗

Phenomenological implication of KamLAND on lepton mass matrices

By using a model independent Monte Carlo approach, we study the possible structure of charged and neutral lepton mass matrices, under the assumption of an U(2) horizontal symmetry (additional to the usual Standard Model ones) involving the light fermion generations. We assume the most general Majorana mass matrix for neutrinos. We update the results of our previous similar study, by inserting in the analysis the recent KamLAND data, that contributed to find a final solution to the Solar neutrino problem. The introduction of the new experimental data reduce the allowed regions in the nine dimensional space parameters, and show that our procedure gives stable solutions.

hep-ph↗

Neutrino masses and non abelian horizontal symmetries

Recent neutrino experiments have made very significant progresses and our knowledge of neutrino masses and mixing has considerably improved. In a model independent Monte Carlo approach, we have examined a very large class of textures, in the context of non abelian horizontal symmetries; we have found that neutrino data select only those charged lepton matrices with left-right asymmetric texture. The large atmospheric mixing angle needs m_{23} ~= m_{33}. This result,if combined with similar recent findings for the quark sector in the B oscillations, can be interpreted as a hint for SU(5) unification. In the neutrino sector strict neutrino anarchy is disfavored by data, and at least a factor 2 of suppression in the first row and column of the neutrino majorana mass matrix is required.

hep-ph↗

After Sno and Before Kamland: Present and Future of Solar and Reactor Neutrino Physics

We present a short review of the existing evidence in favor of neutrino mass and neutrino oscillations which come from different kinds of experiments. We focus our attention in particular on solar neutrinos, presenting a review of some recent analysis of all available neutrino oscillation evidence in Solar experiments including the recent $SNO CC$ and $NC$ data. We present in detail the power of the reactor experiment KamLAND for discriminating existing solutions to the SNP and giving accurate information on neutrino masses and mixing angles.

hep-ph↗

KamLAND, solar antineutrinos and their magnetic moment

We investigate the possibility of detecting solar antineutrinos with the KamLAND experiment. These antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. The recent evidence from SNO shows that a) the neutrino oscillates, only around 34% of the initial solar neutrinos arrive at the Earth as electron neutrinos and b) the conversion is mainly into active neutrinos, however a non e, mu, tau component is allowed: the fraction of oscillation into non-mu-tau neutrinos is found to be cos^2(alpha) = 0.08^{+0.20}_{-0.40}. This residual flux could include sterile neutrinos and/or the antineutrinos of the active flavors. KamLAND is potentially sensitive to antineutrinos derived from solar ^8 B neutrinos. In case of negative results, we find that KamLAND could put strict limits on the flux of solar antineutrinos, Phi(^8 B) < 1.0 times 10^4 cm^{-2} s^{-1}, more than one order of magnitude smaller than existing limits, and on their appearance probability P < 0.20-0.15% (95% CL) after 1-3 years of operation. Assuming a concrete model for antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field mu B < 10^{-21} MeV (95% CL). For B ~ 10-100 kG, we would have mu < 10^{-11}-10^{-12} mu_B (95% CL). In the opposite case, if spin-flavor precession is indeed at work even at a non-leading rate, the additional flux of antineutrinos could strongly distort the signal spectrum seen at KamLAND at energies above 4-5 MeV and their contribution should properly be taken into account.

hep-ph↗

KamLAND potentiality on the determination of Neutrino mixing parameters in the post SNO-NC era

We study in detail the power of the reactor experiment kamLAND for discriminating existing solutions to the SNP and giving accurate information on neutrino masses and mixing angles. Assuming the expected signal corresponding to various ``benchmark'' points in the 2 dimensional $(Δm^2,\tan^2 θ)$ mixing plane, we develop a full-fledged $χ^2$ analysis which includes KamLAND spectrum and all the existing solar evidence. A complete modelling of statistical and known systematics errors for 1 and 3 years of data taking is also included, exclusion plots are presented. We find a much higher sensitivity especially for values of $Δm^2$ lying in the central part of the LMA region. The situation would be more complicate for values closer to the border of the LMA region (the so called HLMA region, i.e. $Δm^2 \leq 2 \times 10^{5}$ and $Δm^2 \geq 8-9 \times 10^{-5}$ or $tan^2 θ$ far from $\tan^2 θ= 0.5$). In this case kamLAND, with or without solar evidence, will be able only to select multiple regions in the parameter space, in the sense that different possible values of the parameters would produce the same signal.

hep-ph↗