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# Tag Archives: Evento scientifico

## The FOOT pixel tracker: a CMOS pixel sensors application example

A better knowledge of the nuclear cross sections is becoming essential for the Hadrontherapy improvement and for the astronauts radio-protection. For this purpose the experiment FOOT ( FragmentatiOn Of Target ) has been envisaged. The direct and inverse kinematic approach will be used to measure the cross sections respectively after the Bragg peak and in the proton entrance channel. For this purpose a key element in FOOT is the magnetic spectrometer based on the monolithic active pixel sensor. The pixel tracker is composed by three main elements: the Vertex detector, the bending permanent magnet and a larger acceptance two layer inner tracker. Both the four layer Vertex and the downstream tracker will use the MIMOSA28 pixel sensors developed by the Strasbourg PICSEL group. An overview of the detector with its main simulated characteristics will be described and some details on main implementation problems will also be underlined.

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## Recent advances in CMOS pixel sensors, towards more applications

Pixel sensors built directly from the CMOS integrated circuit technology, as known as CPS or MAPS, are gaining more and more enthusiasts for vertexing and tracking in subatomic physics. Indeed CMOS pixel sensors feature genuinely spatial resolution in the micrometers range and material budget well below 1% of radiation length, which are key assets for these applications. It was less straightforward, and took some developments, to bring MAPS in the realm of nanosecond range time resolution or microsecond integration time, and radiation tolerance matching 10^15 neutron (1 Mev equivalent) per cm2. These last achievements required the depletion of the sensitive volume, which in turn yield an interesting byproduct in term of energy resolution. For instance, 6 keV X-rays can be reconstructed with about 300 eV resolution, roughly just a factor 3 from the absolute Fano limit. Such a performance opens up perspectives for spectroscopy in a broad range of applications, well beyond high energy physics. A less well recognised but nonetheless very strong point of MAPS is their ability to be easily integrated in a system. This stems from two main reasons: these sensors rely on an industrial technology widely used on the consumer market and they can reach extremely low power dissipation, since there is not much amplification required. This seminar intends to introduce briefly the basic operational concept of CMOS pixel sensors and then to cover the latest developments pushing performances (energy, timing, smartness) to their current limits. These discussions will embark us on a journey through the ...

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## Proposal for using DAFNE as pulse stretcher for the Linac positron beam

A possible application of DAFNE after the end of the Siddharta RUN is using the positron ring as Linac pulse stretcher to produce a high duty=factor beam. The PADME experiment, dedicated to the search for the dark photon (A’), is going to use the BTF beam with 200 ns pulse length and 49 Hz repetition rate, corresponding to a duty-factor of 10e-5. The low duty-factor is the major limitation for the PADME experiment at BTF. By injecting the beam in the DAFNE positron ring and by extracting it with a slow resonant extraction on the m/3 resonance, a duty factor (10e-2 = 0.2/20 ms) nearly a factor 1000 larger can be achieved. This extracted beam would be extremely interesting for PADME. In this talk the modifications required for the ring and the transfer line and a lattice satisfying the conditions for the resonant extraction will be presented. A preliminary estimate of the characteristics of the extracted beam extraction and a description of the work still needed to optimize the parameters will be given.

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## Workshop Quantum Foundations: New frontiers in testing quantum mechanics from underground to the space

The aim of the “New frontiers in testing quantum mechanics from underground to the space” workshop is to discuss the possible limits of validity of quantum mechanics, including the theories which go beyond the standard quantum mechanics, as well as experiments aiming to test them. The role which gravity may play in this context will be discussed, together with future strategies. Testing quantum mechanics in experiments performed in underground laboratories, in earth-based laboratories and in space, in order to make a decisive step forward towards a deeper understanding of quantum mechanics and of the observational process, if fundamental for a deeper understanding of Nature and Universe and also for the future quantum technologies. The workshop is organized in the framework of the Foundational Questions Institute, FQXi, 2017 mini-grant Spring project: Observers and Observations from Underground to Space, and is sponsored by the Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma, by INFN and by the John Templeton Foundation (" Hunt for the “impossible atoms” project). Organizers: Angelo Bassi, Univ. and INFN Trieste, Italy Catalina Curceanu, LNF-INFN, Italy (Chair) Johann Marton, SMI-Vienna, Austria Kristian Piscicchia, Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi Roma, and LNF-INFN Frascati (Roma), Italy Alessandro Scordo, LNF-INFN, Italy

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## Autumn Institute II: Testing the Standard Model at low and high energies

Aim of the workshop: The Autumn Institute II will gather theorists and experimentalists, working mostly in the Rome area and at CERN in the field of collider physics. In an informal environment, we shall investigate a few selected topics on possible tests of the Standard Model at low and high energies. In particular, we will discuss open issues in the dark sectors (dark photons and dark matter), the prospects for Lepton Flavour Violation in the Mu2e experiment, tests of discrete symmetries, such as CP and CPT at KLOE, as well as the latest observations of top-pair production in association with Higgs bosons at the LHC. Speakers: Barbara Mele (INFN Roma) "Searching for a massless dark photon" Stefano Miscetti (INFN LNF) "Mu2e: The search for muon-to-electron conversion at Fermilab" Doojin Kim (CERN) "Searches for Relativistic' Inelastic Dark Matter" Valentina Vecchio (Università di Roma 3) "Evidence for ttH production with the ATLAS detector" Antonio Di Domenico (Università di Roma La Sapienza') "Test of discrete symmetries with neutral kaons at KLOE-2"

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## Calculation of the critical temperature for Fermi superfluid throughout the BCS-BEC crossover.

The problem of the theoretical description of the critical temperature Tc of a Fermi superfluid dates back to the work of Gor’kov and Melik-Barkhudarov (GMB), who addressed it for a weakly-coupled (dilute) superfluid in what would today be referred to as the (extreme) BCS (weak-coupling) limit of the BCS-BEC crossover. The point made in this context by GMB was that particle-particle (pairing) excitations, which are responsible for superfluidity to occur below Tc, and particle-hole excitations, which give rise to screening also in a normal system, get e ectively disentangled from each other in the BCS limit, thus yielding a reduction by a factor 2:2 of the value of Tc obtained when neglecting screening e ects. Subsequent work on this topic, that was aimed at extending the original GMB argument away from the BCS limit, has tout court kept this disentangling between pairing and screening throughout the BCS-BEC crossover, without realising that the conditions for it to be valid are soon violated away from the BCS limit. Here, we reconsider this problem from a more general perspective and argue that pairing and screening are intrinsically entangled with each other along the whole BCS-BEC crossover but for the BCS limit considered by GMB, with the particle-hole excitations soon transmuting into particle-particle excitations away from this limit. We substantiate our argument by performing a detailed numerical calculation of the GMB diagrammatic contribution suitably extended to the whole BCS-BEC crossover, where the full wave-vector and frequency dependence occurring in the repeated two-particle in medium ...

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## The challenge of the Heterogeneous Computing: the CMS case for 2020s

Starting from 2020, during LHC Run 3, the increased accelerator luminosity with the consequently increased number of simultaneous proton-proton collisions (pile-up) will pose significant new challenges for the CMS experiment. The primary goal of the HLT is to apply a specific set of physics selection algorithms and to accept the events with the most interesting physics content. To cope with the incoming event rate, the online reconstruction of a single event for the HLT has to be done within 220ms on average. The increasing complexity of events will make track reconstruction especially challenging. For this reason, reconstruction of Pixel Tracks is not executed for every event or is executed in ROIs.

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## Studies of Baryon Resonances with the HADES Spectrometer and Pion Beams @ GSI

The HADES (High Acceptance DiElectron Spectrometer) detector, installed at GSI in Darmstadt, was designed to measure e+epairs (dielectrons) in the 13.5 AGeV energy range. The experimental program of HADES focuses on two main goals. The first one is to measure dielectron emission from a compressed baryonic matter formed in heavy ion collisions and investigate inmedium hadron properties. The second goal is to study dielectron production in elementary proton–proton (pp) and pion–proton (mp) collisions and learn about hadron electromagnetic structure. Both objectives are complementary in a sense that the understanding of the in-medium effects involves also investigations of the dielectron invariant mass spectra in elementary mp,pp reactions. The elementary collisions, especially those with pion beams, also offer a great opportunity to unambiguously fix the description of baryonic resonances and their coupling to the light vector mesons (rho/omega) which plays essential role for the inmedium modifications. Therefore, to understand resonances production mechanisms a systematic energy scan and high precision data are needed. In 2014 a large dataset of m-p scattering have been obtained at four pion beam momenta (0.656, 0.69, 0.748 and 0.8 GeV/c). The data have been included into the multichannel Partial Wave Analysis (PWA) developed by the BonnGatchina group. A combined PWA analysis of all available data provides better understanding of the vector mesonresonance couplings and their impact on the transition formfactors. Recently, a new model of dielectrons productions in the exclusive reaction m N->Ne+e- within an effective field theory approach was proposed. Experimental and theoretical investigations of the reaction ...

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