Tag Archives: Evento scientifico

I discuss scenarios in which a dark light sector couples to the Standard Model via the so-called “neutrino portal”. A generic implication of this framework is the existence of gauge-singlet fermions (sterile neutrinos) that act as messengers between the dark sector and the active neutrinos. I show under which conditions cosmological constraints become inefficient and discuss what new phenomena neutrino oscillation​ experiments may be able to observe.

When a fast particle is moving close to parallel to a chain of atoms in a crystal or nanotube, particle scattering by atoms becomes strongly correlated, being described by effective Lindhard field, the strength of which can exceed 10^11 eV/cm, equivalent to tens of kilotesla. This field can be a source of both to new fundamental phenomena and various applications. Indeed, coherent effects in particle scattering by atomic string the scattering process much more intense than that in amorphous medium. The point is that all the typical angles, in that number the ones of particle incidence w.r.t. atomic strings, decrease with energy making the scattering by the latter more and more intensive and advantageous for applications. Among the latter are the halo scraping of superconducting accelerator beams, measurement of short living neutral charm and beauty hyperon magnetic and electric dipole moments, intense coherent radiation process, which can be used both for radiation production and study of Landau-Pomeranchuk effect, greatly enhanced in comparison with amorphous substance. These possible applications rise up a question of adequate treatment of particle scattering by atomic strings. A model of chaotic or random particle scattering by the latter is known since 70-th. However both the detail experimental and computer studies of the last decade have demonstrated that this simple and attractive model is considerably violated by the particle capture into the regime of channeling in the field of planes formed by atomic strings in crystals, especially at large thicknesses of the latter. In addition, the effect …

Quest’anno i Laboratori Nazionali di Frascati (LNF) dell’INFN desiderano proporre un incontro con gli studenti universitari in procinto di chiedere una tesi magistrale, per illustrare il programma scientifico e tecnologico dei laboratori e per proporre occasioni di attivita’ di ricerca all’interno di un gruppo sperimentale. I LNF sono protagonisti nello sviluppo di nuove macchine acceleratrici ma anche nella realizzazione di rivelatori, dai tubi a streamer, alla grande camera a deriva dell’esperimento KLOE, ai più recenti rivelatori a MPGD (Micro Pattern Gas Detectors), etc. Inoltre, la comunità scientifica dei LNF è impegnata in diverse collaborazioni internazionali al CERN di Ginevra, negli Stati Uniti, in Giappone, in Cina e negli altri laboratori dell’INFN. La presenza di un programma di ricerca scientifica e tecnologica di altissima qualità rende i nostri Laboratori un’ottima scuola per formare le nuove generazioni alla ricerca.    

We shall present result of investigation of free-standing graphene using angular patterns of transmitted non-neutralized 5-keV protons. The main purpose of this study is to show that structural stability of the rainbow scattering process (i.e. its robustness and high sensitivity) could be used as a tool for studying proton-graphene interaction. To demonstrate sensitivity of the effect on the fine details of the interaction potential we have constructed the static proton-graphene interaction potential using: Doyle-Turner, ZBL, and Molière proton-carbon interaction potentials. The effect of the thermal vibrations was incorporated by averaging the static proton-graphene interaction potentials over the distribution of the atom thermal vibrations. Proton trajectories were obtained by numerical solution of the corresponding Newton’s equations of motion and used to construct the mapping of initial positions to corresponding scattering angles. Multiplicity and singularities (i.e. rainbow lines) of the introduced mapping were used to explain important features of calculated angular distributions, and to demonstrate significant difference in the shape of transmitted yields corresponding to the different assumed proton-carbon interaction potentials. We have also investigated graphene thermal vibrations in detail. Covariance matrix of graphene atom displacements was modeled according the Debye theory, and calculated using Molecular Dynamic approach. The shape of transmitted angular yields and their evolution with the change of the tilt angle was explained by the corresponding evolution of introduced singularities. Rainbow lines formed by protons experiencing the close collisions with the carbon atoms were modeled by elliptical lines which parameters were find to be very sensitive to the structure …

This talk will be devoted to the rainbow proton-silicon interaction potential. We show that it can be obtained as a modification of the corresponding Molière proton-silicon interaction potential by applying the theory of crystal rainbows [1] and the experimental high-resolution angular pattern of 2 MeV protons transmitted through a 55 nm thick Si crystal [2]. The fitting procedure has been performed so that the peripheral rainbow line, generated by the corresponding ZBL interaction potential [3], and the central rainbow line, generated by the Molière interaction potential used by Krause et al. [4], were at the same time well approximated by the rainbow lines generated by the rainbow interaction potential. As a result, the theoretical angular distributions of transmitted protons are in excellent agreement with the corresponding experimental ones. Possible applications of the rainbow ion–atom interaction potential has been discussed. [1] S. Petrović, L. Miletić, and N. Nešković, Theory of rainbows in thin crystals: The explanation of ion channeling applied to Ne10+ ions transmitted through a thin crystal, Phys. Rev. B 61, 184 (2000). [2] M. Motapothula, S. Petrović, N. Nešković, Z. Y. Dang, M. B. H. Breese, M. A. Rana, and A. Osman, Origin of ringlike angular distributions observed in rainbow channeling in ultrathin crystals, Phys. Rev. B 86, 205426 (2012). [3] J. F. Ziegler, J. P. Biersack and U. Littmark, The stopping and range of ions in solids (Pergamon Press, 1985). [4] H. F. Krause, J. H. Barrett, S. Datz, P. F. Dittner, N. L. Jones, J. Gomez del …

The INFN-Milan proposes the design of a Multi-disciplinary Advanced Infra-structure for Research with X-rays (MariX) to be installed in the future Technological Pole of the University of Milan, by the Expo area. MariX will be an FEL (free electron laser) light source and it will produce highly coherent X-rays, in the range 1-5 keV, with ultra-short pulses (10-50 fs) and a repetition rate up to 1MHz. At the same time, MariX will host a compact monochromatic X-ray source, called BriXS, by using an inverse-Compton scattering scheme, with energies up to 150 keV and a repetition rate of 100 MHz (continuous-wave CW operation) that will generate fluxes up to 1013 photons per second. In this presentation, the main guidelines for the electron injector will be discussed as well as the choices for the main operating layouts and parameters for CW (continuous-wave) operation, such as the electron gun and the accelerating linear accelerators.

Inflation is a phase of accelerated expansion, taking place at very high energy in the early Universe. During this epoch, inhomogeneities are generated on cosmological scales from the amplification of quantum fluctuations of the gravitational and matter fields, that are stretched to distances of astrophysical interest today. Inflation has become a very active field of research because the energy scales involved during this early epoch are many orders of magnitude greater than those accessible in particle physics experiments. The early Universe is thus one of the most promising probes to test far beyond standard model physics. I will review the current theoretical and observational status of cosmic inflation, and discuss what we may learn from future experiments.

One of the main goals of the SPARC Lab activities is to deliver high qual- ity electron beam accelerated in plasma. The quality of the beam in plasma basedacceleration depends on the proper matching of the beam before the injection to the plasma and after the acceleration. In order to succeed in both of thosetasks a proper diagnostics system is a paramount. Thus in this work our main objective is creation/modification of the conventional diagnostics tools to meet the requirements for the plasma based acceleration. Namely, the matching of the beam to the plasma requires sub-micron resolution in transverse and f s resolution in longitudinal directions. Alongside with conventional tools at SPARC Lab we investigate an alter- native possibilities for diagnostics. Duringthe plasma wake-field acceleration the electron beams emit so called betatron radiation (BR). Since the param- eters of BR (e.g. spectrum) depend on parameters of the beam, we study the possibilities to use BR in order to reconstruct certain parameters of the beam – its transverse size for example

The XIX LNF Spring School “Bruno Touschek” in Nuclear, Subnuclear and Astroparticle Physics will take place at the INFN, Laboratori Nazionali di Frascati, Italy from Monday, May 7th to Friday, May 11th, 2018. The School is intended for graduate students and post-doctoral fellows in theoretical and experimental high-energy physics. The 2018 edition of the School includes lectures on selected theoretical and experimental topics, discussion sessions, and the 6th Young Researchers Workshop on `Physics Challenges in the LHC Era’, which will take place on Monday, May 7th and on Thursday, May 10th. Students planning to participate in the School are strongly encouraged to apply to give a presentation of their research in the Workshop. The contributions will be published in Frascati Physics Series. A few fellowships covering the registration fee and/or accommodation are available for selected participants giving talks. The XIX LNF Spring School program will also feature the Spring School Colloquium `The Origin of Life The Incredible Experiments of the Evolution in the Primordial Seas’, given by Marco Signore, Senior Researcher at Stazione Zoologica ‘Anton Dohrn’, Naples. The 2018 edition of the School consists of six sets of lectures, divided equally between theoretical and experimental topics, two discussion sessions, and the Spring School Colloquium on Science and Technology. Lecture topics: Dark Sectors: Theory Experimental Searches for Axions and Axion-Like Particles Experimental Searches for Dark Photons Top-quark and Higgs Physics at the LHC: Theory and Experiments Gravitational Waves: Theory, Detectors and Data Analysis Invited Lecturers: Maxim Pospelov (Victoria U. & Perimeter …