Colloqui di Dipartimento / Physics Colloquia

Europe/Rome
412C (Room)

412C

Room

Stefania Vecchi (Istituto Nazionale di Fisica Nucleare)
Description

link ai video dei seminari: https://www.youtube.com/c/FisicaScienzeDellaTerraFerrara/videos

    • 2:30 PM 3:30 PM
      Let there be light: illuminating neutron star mergers at the dawn of a multi-messenger gravitational-wave era 1h

      On August 17, 2017, the detection of light and gravitational waves from the merger of two neutron stars was a watershed moment in history and marked year zero of the multi-messenger gravitational-wave era. The joint detection of gravitational and electromagnetic waves from the same source provided a new window to answer fundamental questions in physics and astrophysics, including the origin of some heavy elements we find on Earth, the rate of expansion of our Universe and the equation of state of nuclear matter. In this colloquium, I will first review what we learned from this first multi-messenger event and then discuss the prospects of detecting more of them in the coming years, thanks to the advent of new and improved gravitational-wave and electromagnetic facilities. In particular, I will show how radiative transfer simulations can illuminate neutron star mergers and provide predictions that are crucial to properly interpret data, place constraints on models and guide future follow-up campaigns of gravitational-wave events.

      Speaker: Mattia Bulla (Istituto Nazionale di Fisica Nucleare)
    • 4:00 PM 5:00 PM
      The Quantum Vacuum: where nothing is actually something 1h

      In the early nineteen-hundreds special relativity and quantum mechanics were discovered. One intrinsic consequence deriving from Einstein's energy-mass equation, Heisenberg's uncertainty principle and Dirac's relativistic equation of the electron is the zero-point energy leading to field fluctuations of both boson fields (e.g. photons) and fermion fields (e.g. electrons). Together, the three discoveries revolutionised the idea of vacuum but also led to a series of fundamental problems: among others, the incompatibility of vacuum energy with measurements and the violation of the superposition principle in electrodynamics leading to light-by-light interaction and field dependent speed of light. In particular, in the presence of an external magnetic field, vacuum is predicted to behave as a birefringent crystal. This last quantum macroscopic effect stems from the 1935 nonlinear effective Lagrangian density for free electromagnetic fields by H. Euler and and B. Kockel. Due to its weakness, the effect is still awaiting a direct experimental confirmation: the induced birefringence due to an external magnetic field B perpendicular to the direction of propagation is An = 4×10^-24 x B^2 (with B in tesla). In the Department of Physics and Earth Sciences and INN of Ferrara we built a polarimeter whose goal was to measure this tiny effect. Although the PLAS experiment has set the present best limits on vacuum magnetic birefringence it missed the goal by less than a factor 10. The theme will be introduced, a description of the PVLAS experiment will be given and possible developments will be presented.

      Speaker: Guido Zavattini (Istituto Nazionale di Fisica Nucleare)
    • 4:00 PM 5:00 PM
      Finding gravitational waves with artificial intelligence 1h

      The search for gravitational wave signals in the data collected by the current ground-based interferometers is a complex problem, especially when only one detector is operating. Modern deep learning approaches may contribute to find a solution. I'll discuss the gravitational-wave events detection problem, and present recent works related to signal detection and noise removal (''de-noising''), where we have investigates performance of various neural networks architectures for classification and auto-encoding, focusing on designs to process time-series data. Last but not least, I will show results from real LIGO-Virgo data, and discuss possibilities of detecting new gravitational events using these methods.

      Speaker: Michal Stanislaw Bejger (Istituto Nazionale di Fisica Nucleare)
    • 4:00 PM 5:00 PM
      Geoneutrinos and geoscience: an intriguing joint-venture. 1h

      Geoneutrinos, the electron antineutrinos originating from the decay chains of uranium and thorium within the Earth's crust and mantle, offer a unique insight into the internal dynamics and composition of our planet.
      These elusive particles carry crucial information about the geochemical processes occurring deep within the Earth, thus addressing pivotal questions related to Earth's heat production and its geological evolution. To date, significant experimental efforts, such as the KamLAND experiment in Japan and the Borexino experiment in Italy, have successfully detected geoneutrinos, shedding light on the Earth's internal mechanisms and the distribution of heat-producing elements. These endeavors have paved the way for future investigations, with the upcoming JUNO experiment in China and the SNO+ experiment in Canada poised to significantly enhance our understanding of geoneutrinos. The JUNO experiment, in particular, with its unprecedented sensitivity, promises to refine our knowledge of the radiogenic contribution to the Earth's heat production, offering new insights into the Earth's formation and its thermal evolution.
      This seminar will explore the intersection of geoscience and particle physics through the lens of geoneutrino research, highlighting the achievements thus far and the exciting potential of future experiments to further unravel the mysteries of our planet.

      Speaker: Fabio Mantovani (Università di Ferrara e INFN)
    • 3:30 PM 4:30 PM
      The BESIII experiment: yin and yang of physics 1h

      BESIII is an experiment running at the Beijing electron-positron collider (BEPCII), based at the IHEP laboratory of the Chinese Academy of Sciences. The collider BEPCII is a multibunch machine which operates in the energy range 2-4.95 GeV in the laboratory center of mass. BESIII is steadily
      operating since 2009 and has collected the world's largest samples of J/ψ, ψ(2s) and ψ(3770). It has the unique opportunity to collect data directly in the region of the new XYZ states: this allows BESIII to have a major role in understanding the nature of these states, and search for new and exotic states. In the summer of 2024, both the spectrometer and accelerator will go through an upgrade program to continue data taking until beyond 2030. The Italian groups are leading an international collaboration to upgrade the inner tracker with a new cylindrical GEM detector, designed and built between Italy and China. This seminar is a journey throughout the two souls of the Italian BESIII group: the Yin (detector development) and the Yang (data analysis). Are you ready for this journey?

      Speaker: Isabella Garzia (Dipartimento di Fisica e Scienze della Terra, UniFe e INFN, sezione di Ferrara)
    • 4:00 PM 5:00 PM
      All you wanted to know about FPGAs as compute accelerators. 1h

      Nowadays, the use of hardware accelerators to boost the performance of software applications is a consolidated practice, and among others, GPUs are by far the most widespread. Despite of this, also FPGAs have been successfully deployed to process front-end experimental data, or to boost machine learning inference algorithms, and their adoption could become more common also for other kind of workloads in the next future.
      In this seminar the architecture of FPGAs will be initially presented, along with the available programming frameworks for such devices.
      Then, after a brief discussion about the problem of theoretically estimating FPGAs performance, it will be introduced FER (FPGA Empirical Roofline), a benchmarking tool developed here in Ferrara, able to empirically measure the computing performance of FPGA based accelerators. Empirical results measured by FER on several AMD-Xilinx Alveo cards will be shown and compared with other processors.
      Eventually, actual use cases will be discussed as well, showing some of the applications which could benefit from FPGA accelerators, spanning from Deep Learning inference to custom data processing.

      Speaker: Enrico Calore (Istituto Nazionale di Fisica Nucleare)