Luisa Cifarelli's scientific activity, carried out within her research group, concerns subnuclear, nuclear and fundamental interactions experiments. The specific themes of the research relative to the last three years mainly concern three experiments.
1) The ALICE experiment at LHC (CERN), to study ultrarelativistic heavy nuclei (Pb-Pb) interactions, in which the elementary constituents of nucleons under very high energy and temperature conditions should form a particular state of matter: the so-called Quark-Gluon Plasma. The nucleon constituents, under very high energy and temperature conditions, form a multi-body system dominated by colour forces, giving rise to a Quark-Gluon Plasma (QGP). The ALICE experiment, performed by an international collaboration of about 1000 researchers, is located at the CERN's Large Hadron Collider (LHC), which was operational in 2009. The Bologna group (University/INFN) has the full responsibility of the TOF detector for the measurement of the flight time of the charged particles produced in the central pseudorapidity zone and therefore for the identification of pions, kaons and protons with momenta of about 0.5 to 2.5 GeV/c (4 GeV/c for K/p separation). The TOF consists of 18 Super Modules (9.3 m long and 1.4 tons heavy) containing the active detectors called Multigap Resistive Plate Chambers (MRPCs), developed by the Bologna group, and all the associated electronics (157248 channels in total). Currently, the Bologna group is devoted to several lines of analysis of data collected in (p-p), (p-Pb) and (Pb-Pb), concerning the inclusive production of various types of hadrons and hadronic resonances.
2) The DarkSide experiment at the Gran Sasso (LNGS) laboratory of INFN to search for dark matter with a new liquid argon apparatus. The existence of this “dark matter” is consistent with evidence from large-scale galaxy surveys and cosmic microwave background measurements, which indicate that the majority of matter in the universe is non-baryonic. The nature of this non-baryonic component is still totally unknown, and the resolution of the “dark matter puzzle” is of fundamental importance. One leading explanation is that dark matter is comprised of as-yet-undiscovered Weakly Interacting Massive Particles (WIMPs) formed in the early universe and subsequently gravitationally clustered in association with baryonic matter. In principle, WIMPs could be detected in terrestrial experiments through their collisions with ordinary nuclei, giving observable low-energy (<100 keV) nuclear recoils. The predicted collision rates are extremely small and require ultra-low background detectors with large (1–100 ton) target masses, located in deep underground sites to eliminate neutron background coming from cosmic ray muons. Among a number of developing detector technologies, two-phase liquid argon time projection chambers (LAr TPCs), which detect scintillation light and ionization generated by recoiling nuclei, are particularly promising. DarkSide-50 (DS-50), the first physics detector of the DarkSide program, with a 50 kg active mass of liquid argon, produced its first WIMP search results using argon from the atmosphere in December 2014. In October 2015, DS-50 produced the first ever WIMP search results using low-radioactivity underground argon. While DarkSide-50 will continue to take data for the next few years, research and development to build and operate a series of larger DarkSide LAr TPCs for WIMP detection is also being carried out. The intent is to progress to multi-ton detectors with the highest sensitivity for high mass WIMP detection.
3) The EEE experiment, to search for extensive cosmic showers through 50 detectors each consisting of three MRPC chambers, installed in an equal number of high schools across the Italian territory, including the islands, to cover an area of about half a million km2. All detectors, called telescopes, send data via the Internet to the data collection center of Bologna's INFN-CNAF where they are processed and prepared for physical studies. The experiment combines research in astroparticle physics with an initiative of wide-ranging dissemination of scientific culture. Given the geographic configuration of the experiment, measurements such as changes in cosmic ray fluxes with solar eruptions or the correlation between cosmic showers at distances of hundreds of kilometers represent important contributions from EEE research in this field.
