LNF Spring School

Program

Young Researchers Workshop – Program

Monday, May 7^th
16:30-16:45	The KLOE-2 Experiment at DAFNE Xiaolin Kang (INFN LNF) In the past four years, the KLOE-2 experiment collected more than 5/pb data at DAFNE, the INFN e+e- collider located in the Frascati National Laboratories. The experiment has a wide physics program ranging from: discrete symmetries test, study of light unflavored mesons, searches for light mass for dark matter candidates, and electron-positron taggers for the gamma-gamma physics. An overview of the KLOE-2 experiment will be given including the performance of the KLOE-2 detector, data taking conditions and some of the ongoing analysis.
16:45-17:00	Dark Mediator results in KLOE/KLOE-2 Elena Perez Del Rio (INFN LNF) In the last years, searches of a fifth force to explain many astrophysical observations and the g-2 anomaly have been performed. The carrier of this force, a new boson called sometimes `dark photon', intermediary between the Dark Matter particles and the Standard Model has been searched by the KLOE experiment by investigating the Phi-Dalitz decay into the eta meson, the direct production of the dark boson from continuum and the Higgsstrahlung process, where it is produced together with a `dark Higgs'. Constraint in the coupling strength of this new force have been set for a large mass range. The newest analysis combines the KLOE data to significantly improve the sensitivity in the mass-region where the `dark photon' mixes with the rho meson. This talk intends to serve as a small overview of the new KLOE searches of the dark photon, with an update in the coupling constant limits from the combined analysis of the KLOE data. New analyses will profit of the KLOE-2 data, which will allow to improve the sensitivity of all exploited processes by a factor of 2. Moreover, new models are to be investigated with the KLOE-2 sample, which has collected more than 5 fb-1 in the past 3 years.
17:00-17:15	Searching for dark photon with the PADME experiment Clara Taruggi (INFN LNF) Despite cosmological evidences, the detection of dark matter has been quite difficult to accomplish so far. For this reason, we can assume that the coupling between ordinary matter and DM is quite weak. One of the most simple model that describes this weak coupling introduces a new symmetry U(1) and a vector-boson mediator, called dark photon A' in analogy to the standard photon. The PADME experiment will be held at Laboratori Nazionali di Frascati (LNF) to explore the coupling between ordinary matter and dark matter (DM) through the detection of Standard Model photons produced in the reaction e+e- -> gamma A'. The measurement of the photon 4-momentum allows us to reconstruct the missing mass spectrum of the process, where the A' would appear as a peak. The experiment technique and its physical implications will be described.
17:15-17:30	A Diamond Active target for the PADME experiment Federica Oliva (Universita' del Salento and INFN Lecce) PADME is a new experiment that is going to search for a dark photon in the annihilation between a positron of a beam bunch and an electron of a thin target at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali di Frascati(LNF). A thin diamond is a good candidate for the active target of the PADME experiment thanks to its low atomic number (Z=6), that limits the Bremsstrahlung interactions, main source of background, with respect to annihilation. The missing mass resolution of the dark photon is related to the resolution of its production point, so it is important to have an active target. Currently, the PADME group of Lecce is producing and assembling different prototypes of the diamond target, both with metal contacts and graphitic strips. The PADME active target will be one of the first diamond detectors with graphitic strips ever used in High Energy Physics experiments.
17:30-17:45	On Search for Dark Photon and Its Resonant Production in PADME Experiment Anish Ghoshal (Universita' di Roma 3 and INFN LNF) Dark photon is both theoretically and phenomenologically motivated particle to resolve some of the existing anomalies; one of the most important of them being the recent 8-Be nuclear anomaly. I shall discuss some of the constraints that exist on dark photon and focus on a novel method for its search in the upcoming positron beam-dump experiments with an emphasis on PADME.
17:45-18:00	Resonant production of dark photons in positron beam dump experiments Cristian David Carvajal Ruiz (Universidad de Antioquia) Positrons beam dump experiments have unique features to search for new physics at the intensity frontier. Due to the continued loss of energy from soft photon bremsstrahlung, in the first few radiation lengths of the dump, a positron beam can continuously scan for resonant production of new resonances via e+e- annihilation in the target. In this talk is explored the peculiarities of search with this technique the 17 MeV dark photon invoked to explain the 8Be anomaly in nuclear transitions.
18:00-18:15	HEPD:a new detector for particle and cosmic rays physics Luca Carfora (Universita' di Roma `Tor Vergata' and INFN Roma 2) HEPD (High Energy Particle Detector) is a particle detector for near Earth measurement of electron, proton and light nuclei fluxes from few MeV up to hundreds MeV. It has been developed by the Italian `Limadou' collaboration in the framework of the Chinese- Italian CSES (China Seismo-Electromagnetic Satellite) space mission. This mission, that hosts several payloads devoted to monitoring electric and magnetic fields and plasma perturbations of atmosphere, ionosphere and low magnetosphere, is aimed at studying phenomena of electromagnetic nature and their correlation with geophysics activity, in order to contribute to the monitoring of earthquakes from space. The HEPD will give a strong contribution to the CSES mission by studying the solar-terrestrial environment, Coronal Mass Ejections (CMEs), Solar Energetic Particle (SEP) events, low-energy cosmic rays and precipitation of inner Van Allen belt particles. The detector consists of a segmented layer of triggering plastic scintillator, a calorimeter, constituted by a tower of 16 plastic scintillator counters, and a LYSO plane. The direction of the incident particle is provided by two layers of double-side silicon microstrip sensors placed above the trigger plane. HEPD has a total mass of 35 kg, a power consumption of less than 38 W and mechanical dimensions roughly 20 x 20 x 40 cm3. CSES satellite was successfully launched on February, 2 nd 2018 and inserted into a circular Sun- syncronous orbit with 98 degrees inclination and 500 km altitude. Expected lifetime is 5 years. In this talk a study on the incident angle reconstruction in HEPD will be presented. An alternative way of measuring the incident angle of a particle of known energy, apart from the silicon planes, is to look at the energy deposited in the silicon or in the trigger plane; this possibility will be widely discussed with the support of simulation Geant4 data.
18:15-18:30	Accidental Peccei-Quinn symmetry in a model of flavour Fredrik Bjorkeroth (INFN LNF) In Peccei-Quinn (PQ) solutions to the strong CP problem, a global U(1)_PQ symmetry is typically added by hand. However, U(1)_PQ need not be exact: it may arise from discrete symmetry, provided the PQ solution is protected to sufficient order. We present a rather complete model, based on Pati-Salam unification and $A_4$, wherein such discrete symmetries are the very same symmetries that govern quark and lepton flavour. The QCD axion itself resides within $A_4$ triplet flavons, which dictate fermion Yukawa structures; axion and flavour scales are firmly linked. Viable avenues for probing the model include: (1) model fitting to quark and lepton mixing, (2) flavour-violating meson and lepton decays, (3) dark matter.
18:30-18:45	Leptonic Dipole Moments Giovanni Marco Pruna (INFN LNF) The first part of the talk reviews the phenomenology of lepton dipole moments in the framework of the Standard Model Effective Field Theory. In the second part, these results are exploited to study the parameter space of an extension of the Standard Model that includes a doubly charged scalar. Then, the phenomenology of this particle at future colliders is explored.

Thursday, May 10^th
16:30-16:45	FTK: an hardware based tracker for the ATLAS experiment Simone Sottocornola (Universita' di Pavia and INFN) During the Run-2 of the Large Hadron Collider (LHC) the instantaneous luminosity exceeds the nominal value of 10^34 with a 25 ns bunch crossing period and the number of overlapping proton-proton interactions per bunch crossing increases up to about 80. These conditions pose a challenge to the trigger system of the experiments that has to control rates while keeping a good efficiency for interesting physics events. In order to cope with these problems, the ATLAS experiment has decided to include, within the existing multilevel trigger architecture, an electronic system, the Fast TracKer (FTK) processor, designed to perform real-time full track reconstruction from the hits observed in the Inner Detector (ID). The Fast Tracker (FTK) system will deliver full event track reconstruction for all tracks with transverse momentum above 1 GeV at a Level-1 rate of 100 kHz with an average latency below 100 microseconds. This will allow the HLT computing farm to free resources and let the trigger system to be more efficient on the selection of event topologies which are difficult to identify, while maintaining a large rejection of the backgrounds. To achieve this goal, FTK exploits hardware technologies with massive parallelism, combining Associative Memory ASICs, FPGAs and high- speed communication links. The functionality of the FTK system as well as an overview of the installation and commissioning status will be presented.
16:45-17:00	Construction and test of the MicroMegas chambers for the upgrade of the ATLAS Muon Spectrometer Giada Mancini (INFN LNF) MICRO MEsh GASeous structure chambers, MicroMegas (MM), is an innovative design concept for Micro-Pattern Gaseous Detectors, designed in order to provide a high spatial resolution and to cope with highly irradiated environments. These chambers have been chosen as new precision tracking detectors for the upgrade of the forward muon spectrometer of the ATLAS experiment. MM trapezoidal detector modules, with areas between 2 and 3 m2, will be part of the two New Small Wheels (NSW) composing the innermost station of the ATLAS muon tracking forward system. MM detectors are composed by 4 read-out layers, two for the reconstruction of the precision coordinate and two with stereo reading (+/- 1.5 degrees) for the reconstruction of also the second coordinate. MM chambers are designed to provide efficiency better than 95% per single plane at rate capability up to 15 kHz/cm2, in presence of magnetic fields up to 0.3 T. The Istituto Nazionale di Fisica Nucleare (INFN) is deeply involved in the construction of these chambers and in their validation at the Cosmic Ray Stand in the Frascati INFN site (LNF). Preliminary results of the tests performed on INFN SM1 prototype at LNF are presented.
17:00-17:15	Preliminary study for ttbar resonance search in dilepton channel and performance of muon reconstruction close to jets in ATLAS Maurizio De Santis (Universita' di Roma `Tor Vergata' and INFN) The presentation is divided into two main parts. A first part concerns a search for ttbar resonances in the dilepton channel: this channel has a branching ratio of only the 5% of the total, but it is very clean in terms of background and, more importantly, it is more sensitive to variations of ttbar spin correlation, variations exepected from various new physics signals in specific ttbar invariant mass ranges; the idea is then to combine ttbar-invariant-mass-related and ttbar-spin-correlation-related observables to improve sensitivity to new physics signals. The second part concerns the determination of the reconstruction efficiency Scale Factors (SFs) for muons close to jets, useful for analyses involving heavy jets (e.g. muons near b or c jets); these SFs are the first ever obtained in the Muon Combined Performance (MCP) group in ATLAS.
17:15-17:30	The Mu2e experiment at Fermilab: R&D, design and status Eleonora Diociaiuti (Universita' di Roma `Tor Vergata' and INFN LNF) The Mu2e Experiment at Fermilab will search for coherent, neutrinoless conversion of negative muons into electrons in the field of an aluminum nucleus, mu + N(A,Z)-> e + N(A,Z). This is an example of Charged Lepton Flavour Violation (CLFV) never observed experimentally. The dynamics of such a process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass (about 104.967 MeV). If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between conversion and capture rate R_{mu,e}<6x10^(-17) (@ 90% C.L.). This will improve the current limit of a factor of 104 over previous experiments. The experiment complements and extends the current/planned searches (MEG , mu3e) as well as the direct searches for new physics at the LHC. Indeed, such a CLFV searches in the muon sector probe new physics at a mass scale inaccessible with direct searches at either present or planned high energy colliders. To detecy the muon conversion process, a very intense pulsed beam of negative muons is produced by means of a S-shape Superconducting Solenoid Magnet System that is organized into three sub-systems: the Production Solenoid, the Transport Solenoid and the Detector Solenoid. The beam is stopped at 10 GHz on an Aluminum target inside the Detector Solenoid. The Mu2e detectors, also installed inside the Detector Solenoid, are a high-precision tracker made on about 20000 straw tubes, and a calorimeter composed of about 1500 pure CsI crystals organized in two disks and readout by two large area UV-extended Silicon Photomultipliers (SiPMs). The Detector Solenoid region is surrounded by a Cosmic Ray Veto based on scintillators readout by SiPMs.
17:30-17:45	Design and status of the Mu2e crystal electromagnetic calorimeter Raffaella Donghia (Universita' di Roma 3 and INFN LNF) The Mu2e experiment at Fermilab will search for the charged-lepton flavour violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. The Mu2e detector is composed of a tracker and an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities, a fast online trigger filter while aiding the track reconstruction capabilities. The calorimeter requirements are to provide a large acceptance for 100 MeV electrons and reach: a time resolution better than 0.5 ns @ 100 MeV; an energy resolution O(10%) @ 100 MeV; a position resolution of 1 cm. The calorimeter consists s of two disks, each one made of 674 pure CsI crystals readout by two large area array 2x3 UV extended SiPM 6x6 mm^2. We report here all progresses done for the construction and test of the latest large scale prototype that consists of an array of 51 pre-production crystals. Each crystal has been readout by two pre-production Mu2e SiPMs. The prototype has been exposed to an electron beam in the energy range around 100 MeV at the Beam Test Facility in Frascati (Italy). Satisfying results on the study of timing and energy resolution will be presented as well as the calorimeter construction status.
17:45-18:00	Rho-meson leptoproduction as testfield for the unintegrated gluon distribution in the proton Andree Dafne Bolognino (Universita' della Calabria and INFN Cosenza) The gluon content of the proton is emd bodied by the unintegrated gluon distribution (UGD), which has universal validity. In literature many models of UGD have been proposed so far. The polarized rho-meson leptoproduction at HERA offers a so far unexplored textfield to discriminate among existing models of UGD, via the comparison with theoretical predictions formulated in the kt-factorization approach.
18:00-18:15	Verifying the performance of the Argon-41 monitoring system from Fluoride-18 production for medical applications Nicole Virgili (Universita' di Roma `La Sapienza') In this work, the well-known MC code was used to simulate the TR19PETcyclotron (19 MeV) installed at "A. Gemelli University Hospital (Roma, IT) and routinely used in the production of positron emitting radionuclides. In a medical cyclotron facility, 41Ar(t_1/2 = 109.34 m) is produced by the activation of air due to the neutron flux during irradiation, according to the 40Ar(n,gamma)41Ar reaction; this is particularly relevant in widely diffused high beam current cyclotrons for the production of PET (Positron Emission Tomography) radionuclides, 18F radionuclide in this case. Aim of this work is the determination of the detection efficiency of a Geiger Muller detector placed in the terminal part of the chimney of the cyclotron for environmental monitoring of 41Ar emission through the chimney of the cyclotron. Function of the detector is to reveal the activity of 41Ar produced by the cyclotron. Taking into account the activity of 41Ar inside the bunker of 700 Bq/muA , beam current intensity of 50 muA and 41Ar radioactive decay constant of 1,054x10-4 s-1, the activity of 41Ar emitted and the detection efficiency have been calculated. In conclusion the detection efficiency determinated through the use of Monte Carlo code is very low (4,7 10-7 cps/Bq), consequently the counting rate of 1,3 x 10-2 is low and several studies have now been conducted to find more effective detectors.
18:15-18:30	Search for long-lived neutral particles decaying into lepton-jets with the ATLAS detector in proton-proton collision data at 13 TeV Cristiano Sebastiani (Universita' di Roma `La Sapienza' and INFN) The presentation is divided into two main parts. A first part concerns a search for ttbar resonances in the dilepton channel: this channel has a branching ratio of only the 5% of the total, but it is very clean in terms of background and, more importantly, it is more sensitive to variations of ttbar spin correlation, variations exepected from various new physics signals in specific ttbar invariant mass ranges; the idea is then to combine ttbar-invariant-mass-related and ttbar-spin-correlation-related observables to improve sensitivity to new physics signals. The second part concerns the determination of the reconstruction efficiency Scale Factors (SFs) for muons close to jets, useful for analyses involving heavy jets (e.g. muons near b or c jets); these SFs are the first ever obtained in the Muon Combined Performance (MCP) group in ATLAS.
18:30-18:45	Muon reconstruction and identification in the ATLAS experiment at LHC Damiano Vannicola (Universita' di Roma `La Sapienza' and INFN) Muon reconstruction and identification plays a fundamental role in many primary ATLAS analysis of LHC run 2. It will be showed the algorithms used in ATLAS for muon with transverse momentum from few GeV to the scale TeV, the methods used for the measurements, and the results got from the run-2 data analysis. The region of high pt, and the particular importance of alignment and calibration will be discussed with more details.
18:45-19:00	Search for New Phenomena in dijet events with ATLAS detector at LHC Simone Francescato (Universita' di Roma `La Sapienza' and INFN) Final states with two jets represent one of the important channel when searching for New Phenomena in High Energy experiments because of the high statistics. Dijets events are recorded by ATLAS during the Run2 period at the centre-of-mass energy of 13 TeV. The invariant mass and the angular distributions are analyzed and compared to Standard Model background predictions seeking for evidence of New Physics signals over the dominant QCD contribution. Information from the dijet angular correlations has been deployed to improve the sensitivity towards broad resonances. Results are interpreted in the context of Standard Model extensions, focusing on a particular Dark Matter model.

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