Tag Archives: Evento scientifico

Dark sectors are ubiquitous in physics beyond the Standard Model (SM), and may play a role in explaining many of the long-standing problems of the SM such as the existence of dark matter or the electroweak hierarchy problem. By definition, dark sectors are not charged under any of the known forces. Discovering their possible existence is thus challenging. I will describe how a a broad program combining particle, nuclear and atomic physics experiments can effectively probe a large region of the parameter space. I will show how the unique signatures of such physics can already be searched for with existing/planned experiments, including neutrino-proton fixed-target experiments and precision atomic measurements.

Active plasma lenses are promising technologies for the focusing of high brightness electron beams due to their radially symmetric focusing and their high field gradients (up to several kT/m). However, in a number of experimental situations, the transverse non-uniformity of the current density flowing in the lens causes beam emittance growth and increases the minimum achievable spot size. To study the physics of the capillary discharge processes employed as active plasma lenses, we developed a 2-D hydrodynamic computational model. Here, we present preliminary simulation results and we compare the computed magnetic field profile with one from literature, which has been experimentally inferred. The result of the comparison is discussed.

We present a unique way to detect the jet-medium interaction in p+Pb collisions at 5.02 TeV using 3 particle correlation (C112) observable constructed with particles from low and intermediate pT (0.5 < pT < 10 GeV/c) region. In case of small collision systems, the intrinsic momentum scale of the low energy jets is comparable to the characteristic scale of the medium and therefore have a larger probability of interaction with the medium. The short range of the 3 particle correlation is dominated by the jet like correlation and has a unique charge dependence as observed in the minimum bias p+Au collisions at the RHIC energy. The similar effect has been observed in EPOS in the lower multiplicity classes of p+Pb collisions where jet fragmentation plays the dominant role. Interestingly, the charge dependence of the C112 gets diminished in the higher multiplicity classes of p+Pb collisions where the jet-medium interplay may have significant contribution. The results from EPOS and AMPT and JEWEL will be presented for both p+Pb and Pb+Pb collisions at the LHC energies. The effectiveness of this observable as a probe to study jet-medium interaction in small collision systems will also be discussed.

Jet physics plays an essential role in understanding the nuclear structure at short distance and properties of the hot and dense QCD matter in heavy-ion collisions. The forward rapidity in experiments such as LHCb provide a window for furthering these studies in a difference regime of energy and density. In this talk, I will discuss about jet and electroweak boson studies in p+A collisions which can help to provide constraints on parton distributions in large nuclei. I will also discuss jet quenching in the forward direction and their implication on jet tomography of hot QCD matter.

New generation of particle accelerators is based on the excitation of large amplitude plasma waves driven by either electron or laser beams, named as Plasma Wakefield Accelerator (PWFA) and Laser Wakefield Accelerator (LWFA), respectively. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the local plasma electron density whose shaping is mandatory for ensuring the correct acceleration and manipulation of the electron beams. This presentation will summarize the study on the plasma sources for both these acceleration schemes that will be implemented in the SPARC_LAB test facility.

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 …