Particle Physics and Astroparticles Physics
Participants: M. Bonesini, A. Branca, C. Brizzolari, C. Cattadori, A. Falcone, C. Gotti, G. Pessina, F. Terranova, M. Torti
Particle accelerators can produce high intensity neutrino beams to be detected thousands of kilometers far from the source. Accelerator neutrino beams produce particles whose flux, flavor and energy is extremely well controlled and allow for a detailed study of neutrino oscillations and matter-antimatter asymmetries. The most ambitious accelerator neutrino experiment ever conceived is DUNE: the US flagship facility in particle physics under construction at Fermilab (beam) and South Dakota (detector), and supported by an international collaboration of about 1100 physicists.
Since 2019, the physicists of our Department coordinate the realization of the DUNE photosensors and contribute to the prototyping and data analysis of these detectors at CERN. In addition, we proposed in 2015 a new technique to reduce the systematic uncertainties in DUNE based on the “monitored neutrino beam” concept. In the monitored neutrino beams, the neutrino flux is measured in a direct manner by detecting the charged leptons produced in the decay tunnel. This technique is developed by an experiment approved at CERN in 2019 and called NP06/ENUBET. The experiment is coordinated by the Departments of Milano-Bicocca and Padova.
M.Calvi, S.Capelli, P.Carniti, D. Fazzini, J. García Pardiñas, C.Gotti, M.Martinelli, L. Martinazzoli, C. Matteuzzi, S. Meloni, A.Minotti, G.Pessina, E.B. Shields
LHCb is one of the four main experiments taking data at the large proton-proton collider LHC at the CERN laboratory in Geneva. It is mainly devoted to the physics of beauty and charm hadrons. The Standard Model (SM) has proven to be able to describe experimental results with outstanding success. However it leaves several open questions, like the origin of the matter-antimatter asymmetry in the universe, the reason for the three replica of lepton and quarks families, the large differences existing among their masses and coupling constants etc.. The main aim of LHCb is the search for possible evidences of physics beyond the SM from the comparison of its predictions to very precise measurements. LHCb studies CP violating processes in the beauty and charm sectors and searches for evidence of rare events. LHCb has demonstrated to be well suited for extensive studies of the production and decay of all kinds of beauty and charm hadrons, it has provided a large amount of results which increase the knowledge in hadronic physics. The LHCb detector is going through a major upgrade to resume taking data in 2022 with increased data-taking capabilities.
The Milano group is part of the LHCb Collaboration which consists of physicists coming from 90 Universities and laboratories distributed in 19 different countries, for a total of about 1500 members.
Even today, the absolute value of the neutrino mass is unknown. Measuring it is crucial to complete the picture we have of particle physics and cosmology. The neutrino, in fact, with its abundance in the universe influences its evolution, particularly in the process of galaxy formation, and its mass is also a key ingredient in theoretical models that try to explain how all particles acquire a mass. Direct measurement of neutrino mass through the study of the energy distribution of ionizing particles emitted in nuclear beta decays relies only on conservation of energy and momentum and is therefore the measurement most free from additional model assumptions. At the Criogenics Laboratory located in the basement of the Department of Physics we carry on several activities related to the direct measurement of neutrino mass. For years we have been developing very low-temperature particle detectors (micro-calorimeters), which because of their extreme sensitivity are particularly suitable for these delicate measurements. In particular, these detectors are suitable for studying the beta decay of 187Re and the electron capture of 163Ho (for more information). In the Cryogenics Laboratory we develop detectors and conduct pilot experiments with the aim of defining a future large-scale experiment using 187Re or 163Ho to overcome the sensitivity of experiments currently using tritium. Recently the European Research Council (ERC) funded with an Advanced Grant the HOLMES experiment that will use 163Ho.
P.G. Rancoita, M. Gervasi, M. Zannoni, S. Della Torre, D. Grandi, M .Tacconi, G. La Vacca, D. Rozza, M.J. Boschini, S. Pensotti, G .Boella
The Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art particle physics detector designed to operate as an external module on the International Space Station. It will use the unique environment of space to study the universe and its origin by searching for antimatter, dark matter while performing precision measurements of cosmic rays composition and flux. AMS-02 is built, tested and operated by an international Collaboration of 56 institutions from 16 countries.
M. Gervasi, M. Zannoni, A. Baù, A. Passerini, R. Mainini
B-modes of CMB polarization are signals probing the gravitational waves background released during the inflationary epoch of the primordial universe. QUBIC is a bolometric interferometer operating from Antarctica and LSPE is a stratospheric balloon borne experiment searching for these signals. Besides, the interaction of CMB photons with the intra-cluster medium of galaxy clusters is studied to get information on the physics of the clusters and on the cosmological evolution of stuctures. Spectroscopic obeservations are carried on with OLIMPO program on stratospheric balloon and with Millimetron space program.