seminari 2019

Dipartimento di Fisica e Scienze della Terra

Dipartimento di Fisica e Scienze della Terra

Via Saragat 1, Blocco C, 44122 Ferrara

Seminari di Fisica del Dipartimento di Fisica e Scienze della Terra dell'Università di Ferrara e dell'INFN, sezione di Ferrara

    • 11:30 12:30
      Cosmology with Gaussian process: inferring late-time expansion, implications for H0 and q0. (RINVIATO A DATA DA DEFINIRE) 1h aula 412 (Dip. Fisica e Scienze della Terra)

      aula 412

      Dip. Fisica e Scienze della Terra

      GP has been a popular “model-independent” method, utilised to reconstruct the low-redshift cosmic expansion history, henceforth the dynamics of the late-time evolution. In this talk, I will present an extension of the standard Gaussian Process formalism, the Multi-Task GP with the ability to perform joint learning of several “low-redshift” cosmological data and on the robustness of several assumptions involved. Utilising the ``low-redshift'' expansion-rate we obtain constraints on H0 = 68.52 +- 0.94 (stat) +- 2.51 (sys) km/s Mpc^-1 and a corresponding rd = 145.61 +- 2.82 (stat) +- 4.3 (sys) Mpc. Subsequently, one can further constrain $q_0 = -0.52 \pm 0.06$ and the transition redshift zT = 0.64^{+0.12}_{-0.09}. Using the Om(z) diagnostic, we find that the concordance model is very consistent within the redshift range z<=2 and mildly discrepant for z>2. While GP provides flexibility, it can also lead to biases and incorrect inferences which become more apparent, for higher order derivatives.

      Speaker: Sandeep Haridasu (Universtita di Tor Vergata)
    • 15:00 16:00
      Performances of Lobster Eye Optics and Their calculation. 1h Aula 300 -- Blocco C ()

      Aula 300 -- Blocco C

      The grazing incidence lobster eye X-ray optics is introduced. The main advantage of this concept is large field of view. Two methods of calculation of its performances are presented. First, it is a numerical method based on simplified ray-tracing. The other method is an analytical method of direct calculation of effective collecting length. Results of tests of lobster eye prototypes are shown.

      Speaker: Vladimir Tichy (Leicester University)
    • 15:00 16:00
      A view of the ProtoDUNE Single-Phase experiment at the CERN Neutrino Platform 1h Aula 300 Blocco C ()

      Aula 300 Blocco C

      After some years of planning and two intense years of engineering, fabrication, assembly, installation, and as much commissioning as feasible, the prototype for the single-phase liquid argon detector for the DUNE experiment, ProtoDUNE SP, has been completed, and has been exposed to beam from a new SPS beam line during Fall 2018.
      I will give some examples of the technical challenges addressed by this, the largest liquid argon time projection chamber ever constructed, the solutions adopted, and some initial data on some aspects of the performance of the apparatus.

      Speaker: Enrico Gamberini (CERN Fellow)
    • 16:30 17:30
      Atomic scale metrology 1h Aula 300 ()

      Aula 300

      The activity is focused on the measurement of the (220) lattice plane spacing of silicon by means of combined optical and X-ray interferometry - COXI, which is one of the most advanced tools for atomic-scale displacement metrology. The aim is to determine the spacing of the (220) lattice planes in silicon to within 1 ppb relative uncertainty.

      Speaker: Enrico Massa (Istituto Nazionale di Metrologia)
    • 11:00 12:00
      Hydrodynamic transport in graphene 1h

      Electron-electron (e-e) collisions can impact transport in a variety of surprising and sometimes counterintuitive ways. Despite strong interest, experiments on the subject proved challenging because of the simultaneous presence of different scattering mechanisms that suppress or obscure consequences of e–e scattering. Only recently, sufficiently clean electron systems with transport dominated by e-e collisions have become available, showing behavior characteristic of highly viscous fluids. Examples of these new and counterintuitive measurable phenomena are the negative nonlocal resistance, the occurrence of current whirlpools, and the superballistic transport through a constriction. Furthermore, it is well known that materials subjected to a magnetic field exhibit the Hall effect, a phenomenon studied and understood in fine detail. Here, we report a qualitative breach of this classical behavior in electron systems with high viscosity. The viscous fluid in graphene is found to respond to non-quantizing magnetic fields by producing an electric field opposite to that generated by the classical Hall effect.

      Speaker: Francesco Pellegrino (Universita' di Catania)
    • 15:00 16:00
      The HERMES Project (High Energy Rapid Modular Ensamble of Satellites): Probing Space-time Quantum Foam and Hunting for Gravitational Wave Electromagnetic Counterpart 1h

      I discuss how several of the proposed models for space-time quantization predict an energy dependent speed for photons.
      Although the predicted discrepancies with the general speed of light are minuscule, I discuss how it is possible to detect this intriguing signature of space-time granularity with a new concept of modular observatory for photons in the energy band from few keV to few MeV.
      This observatory may consist of a swarm of micro/nano-satellites on low orbits. Sub-microsecond time resolution and wide energy band allows to probe tiny energy dependent delays, expected to be the signature of the granular structure of space-time in several of the proposed theories of Quantum Gravity.
      Moreover this kind of experiment allows to perform temporal triangulation of high signal to noise impulsive events with positional accuracies of few arcseconds, making an observatory like that a promising hunter for the elusive electromagnetic counterparts of Gravitational Waves.

      Speaker: Luciano Burderi (Universita di Cagliari)
    • 11:30 12:30
      Radiative-transfer effects: a new scale in the bias expansion 1h

      The fact that the spatial nonlocality of galaxy formation is controlled by some short length scale like the Lagrangian radius is the cornerstone of the bias expansion for large-scale-structure tracers.
      However, the first sources of ionizing radiation between z ≈ 15 and z ≈ 6 are expected to have significant effects on the formation of galaxies we observe at lower redshift. These radiative-transfer effects introduce a new scale in the clustering of galaxies, i.e. the mean free path of ionizing radiation.
      This mean free path can be very large, of order 100 Mpc/h. Consequently, higher-derivative terms in the bias expansion could turn out to be non-negligible even on these scales: treating them perturbatively would lead to a massive loss in predictivity and, for example, could spoil constraints on the neutrino mass.
      I discuss under what assumptions an explicit non-perturbative model of radiative transfer can maintain the robustness of large-scale galaxy clustering as a cosmological probe.

      Speaker: Giovanni Cabass (Max Planck Institute for Astrophysics, Garching, DE)
    • 14:00 15:00
      Recent progress in the physics of neutron stars and black holes 1h

      I will review the rapid recent progress made in modelling neutron stars in binary system and the associated gravitational-wave emission. In particular, I will discuss how our understanding on the maximum mass and radii of neutron stars has improved with the detection of GW170817. In addition, I will illustrate how the properties of magnetised accretion flows onto black holes represent the ideal tool to understand the properties of matter in strong gravitational fields and to explain the phenomenology of accreting supermassive and stellar-mass black holes. More specifically, I will review the modelling these flows not only onto rotating black holes in general relativity, but also on other more exotic compact objects. These comprise black holes in alternative theories of gravity, but also horizonless compact objects with and without a surface.

      Speaker: Luciano Rezzolla (Chair of Theoretical (Relativistic) Astrophysics and the Director at the Institute for Theoretical Physics (ITP) of the Goethe University of Frankfurt, Germany.)
    • 15:00 16:00
      Revelations from 2 km Underground: Neutrinos from the Sun and Earth 1h

      Neutrinos are mysterious particles that barely interact with our detectors. Yet physicists have pursued the challenge of neutrino detection for the past few decades in search of physics beyond the Standard Model...and succeeded to unlock the secrets of solar neutrinos -- discovering the phenomenon of neutrino oscillations. One of the key experiments in this effort was the Sudbury Neutrino Observatory (SNO), located 2 km underground in a deep mine in Canada. After the end of the SNO experiment, the detector has been modified into a low-background liquid scintillator detector called SNO+. SNO+ will continue to probe the nature of neutrinos from the Sun and, in addition, will detect geo neutrinos, becoming the third detector in the world with this capability. This talk will tell the story of the discovery of solar neutrino oscillations with SNO and will show how the experiment has been transformed into SNO+, which is poised to start taking data with scintillator in the near future.

      Speaker: Mark Chen (Queen's University, Kingston, Ontario, Canada)
    • 16:00 17:00
      Neutrinos from a blazar jet and the birth of non-stellar neutrino astronomy 1h

      IceCube has recently reported the discovery of high-energy neutrinos of astrophysical origin,
      opening up the PeV (10^15 eV) sky. These observations are challenging to interpret on the
      astronomical side and have triggered a fruitful collaboration across particle and astro-physics.
      I will discuss the very recent association between high-energy IceCube neutrinos and the
      blazar TXS 0506+056, reporting on how this result fits with the work done by our group over
      the past five years. I will then present the “big picture”, explain why this this association is
      very important for astronomy, and discuss some very recent results on the nature of TXS 0506+056.
      The talk is self-contained, requires no previous knowledge of neutrinos or blazars, and has been
      prepared for a very broad audience (astronomers and physicists).

      Speaker: Paolo Padovani (ESO)
    • 14:30 17:50
      ESO Press Conference on First Result from the Event Horizon Telescope (EHT) 3h 20m

      streaming of the ESO press conference presenting a groundbreaking result from the EHT.

      Prima del collegamento il Prof.Rosati fara` una breve introduzione alle misure del BH nel centro galattico, dove la strumentazione ESO VLT ha giuocato un ruolo centrale negli ultimi ~15 anni, fino a questa dell’EHT

      Speaker: Piero Rosati (Dipartimento FST Unife)
    • 11:00 12:00
      Neutrino-nucleus coherent scattering: new physics, experiments and applications. 1h

      After its discovery in 2017, there is a large and growing interest in the coherent elastic neutrino-nucleus scattering (CEvNS): experiments are being conceived and funded worldwide to probe neutrinos from a variety of sources, perform precision measurements and search for new physics. At the same time, thanks to the large cross-sections the process can achieve, applications for non-proliferation purposes are highly promising.
      In this talk I will discuss the physics of CEvNS, review the current experimental efforts and present some possibilities for an INFN involvement in the field.

      Speaker: Vignati Marco (INFN Roma 1)
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