Correlated-photon imaging at 10 volumetric images per second

The correlation properties of light provide an outstanding tool to overcome the limitations of traditional imaging techniques. A relevant case is represented by correlation plenoptic imaging (CPI), a quantum-inspired volumetric imaging protocol employing spatio-temporally correlated photons from either entangled or chaotic sources to address the main limitations of conventional light-field imaging, namely, the poor spatial resolution and the reduced change of perspective for 3D imaging. However, the application potential of high-resolution imaging modalities relying on photon correlations is limited, in practice, by the need to collect a large number of frames. This creates a gap, unacceptable for many relevant tasks, between the time performance of correlated-light imaging and that of traditional imaging methods. In this article, we address this issue by exploiting the photon number correlations intrinsic in chaotic light, combined with a cutting-edge ultrafast sensor made of a large array of single-photon avalanche diodes (SPADs). This combination of source and sensor is embedded within a novel single-lens CPI scheme enabling to acquire 10 volumetric images per second. Our results place correlated-photon imaging at a competitive edge and prove its potential in practical applications.Comment: 13 pages, 6 figure

Demonstration of particle tracking with scintillating fibres read out by a SPAD array sensor and application as a neutrino active target

Scintillating fibre detectors combine sub-mm resolution particle tracking, precise measurements of the particle stopping power and sub-ns time resolution. Typically, fibres are read out with silicon photomultipliers (SiPM). Hence, if fibres with a few hundred mm diameter are used, either they are grouped together and coupled with a single SiPM, losing spatial resolution, or a very large number of electronic channels is required. In this article we propose and provide a first demonstration of a novel configuration which allows each individual scintillating fibre to be read out regardless of the size of its diameter, by imaging them with Single-Photon Avalanche Diode (SPAD) array sensors. Differently from SiPMs, SPAD array sensors provide single-photon detection with single-pixel spatial resolution. In addition, O(us) or faster coincidence of detected photons allows to obtain noise-free images. Such a concept can be particularly advantageous if adopted as a neutrino active target, where scintillating fibres alternated along orthogonal directions can provide isotropic, high-resolution tracking in a dense material and reconstruct the kinematics of low-momentum protons (down to 150 MeV/c), crucial for an accurate characterisation of the neutrino nucleus cross section. In this work the tracking capabilities of a bundle of scintillating fibres coupled to SwissSPAD2 is demonstrated. The impact of such detector configuration in GeV-neutrino experiments is studied with simulations and reported. Finally, future plans, including the development of a new SPAD array sensor optimised for neutrino detection, are discussed

Production of photons from electroweak vector boson fusion in sqrt(s) = 13 TeV proton-proton collisions with the CMS experiment at CERN

The object of this Master's thesis is the measurement of the Electroweak production of photons in association with two jets from proton collisions, with data collected by the CMS experiment at CERN during the ”Run II”. These events are important to test the SU(2)_LxU(1)_Y symmetry of the Electroweak interactions, in particular the self-couplings between the Gauge bosons resulting from the aforementioned symmetry. At the center-of-mass energy of 13 TeV reached at the LHC, the Electroweak production of the photon and the jets also involve Electroweak diagrams in which the photon is produced by the fusion of the massive Vector Bosons W radiated from each of the colliding partons, hence this process is more commonly referred to as Vector Boson Fusion, in particular Vector Boson Fusion to $\gamma$. The cross-section calculated including only the Vector Boson Fusion diagram diverges at high energies resulting in the violation of unitarity. The presence of other Electroweak same final state diagrams which interfere destructively prevents the cross-section from growing indefinitely. This Gauge cancellation mechanism must therefore be extremely precise for it to work, as even slight deviations from the Standard Model predictions would result in the divergence of the cross-section, thus hinting at the presence of new Physics which keeps the cross-section finite at high energies. Therefore this measurement, and more in general Vector Boson Fusion ones, allows to set stringent limits on Physics Beyond the Standard Model, often modelled as Anomalous Gauge Couplings. To measure this process, events with a photon of p_T>220 GeV and two jets with m_{jj}>200 GeV are selected. For signal events, these jets are usually reconstructed using only the information on the electromagnetic and hadronic calorimeters, as they are often outside the acceptance of the tracking system. The photon is instead within the tracker acceptance. This thesis starts with the description of the Standard Model with particular attention to SU(2)_LxU(1)_Y and its Gauge boson self-couplings (chapter 1). The Compact Muon Solenoid experiment at the Large Hadron Collider at CERN is presented in chapter 2. The thesis work started from studies of the main features of the signal using Monte-Carlo simulations only including the Matrix Element calculations (chapter 3), and then moved to study the selection of the correct jets out of all those present in the events, using full Monte-Carlo simulations (chapter 4). Another important feature of Vector Boson Fusion events is the presence of a "rapidity gap" between the jets in which little additional hadronic activity is present. As already said, the jets are mostly outside of the tracking system acceptance, and the only central object is the photon, so few tracks are expected for these events. Because of this, the correct choice of the main Primary Vertex is studied, in particular the fraction of times in which the vertex is chosen correctly. Then characteristics of the vertices chosen correctly and incorrectly are studied, to better understand the causes for the wrong vertex choice. Then the impact of the vertex choice on the invariant mass is studied. This is described in chapter 5. The analysis to measure Electroweak $\gamma+2$ jets is presented in chapter 6. The main background to this analysis is the mixed QCD/EW production of photon in association with jets. This is simulated using full Monte-Carlo simulation, whose predictions are validated by a Control Region with Z->l+ l- events and two jets with the same kinematic cuts. Another important source of background events is the pure QCD production of multijet events in which an object is mistakenly reconstructed as a single isolated photon, this objects are usually $\pi_0$s produced in jets. This source is instead validated using a data-driven approach using the $\sigma_{i\eta i\eta}$ and photon isolation variables. The analysis is performed first in the Control Region and a fit to measure the Electroweak Z-> l+l-+2 jets is performed on the output of a Boosted Decision Tree specifically built to discriminate Electroweak $\gamma+2$ jets events and its main background. This was done for all three years. Then this is repeated on the Signal Region for 2016 and the expected total uncertainty and significance were extracted. Both in Z+2 jets Control Region and the $\gamma+2$ jets Signal Region various sources of systematic uncertainties, Jet Energy Scale and Resolution and the variation of the QCD $\mu_R$ and $\mu_F$ scales. Finally chapter 7 summarizes the results of the various chapters of this thesis and also discusses future directions for this work

Chewing and Cognitive Improvement: The Side Matters

Chewing improves cognitive performance, which is impaired in subjects showing an asymmetry in electromyographic (EMG) masseter activity during clenching. In these subjects, the simultaneous presence of an asymmetry in pupil size (anisocoria) at rest indicates an imbalance in Ascending Reticular Activating System (ARAS) influencing arousal and pupil size. The aim of the present study was to verify whether a trigeminal EMG asymmetry may bias the stimulating effect of chewing on cognition. Cognitive performance and pupil size at rest were recorded before and after 1 min of unilateral chewing in 20 subjects with anisocoria, showing an EMG asymmetry during clenching. Unilateral chewing stimulated performance mainly when it occurred on the side of lower EMG activity (and smaller pupil size). Following chewing on the hypotonic side, changes in cognitive performance were negatively and positively correlated with those in anisocoria and pupil size, respectively. We propose that, following chewing on the hypotonic side, the arousing effects of trigeminal stimulation on performance are enhanced by a rebalancing of ARAS structures. At variance, following chewing on the hypertonic side, the arousing effect of trigeminal stimulation could be partially or completely prevented by the simultaneous increase in ARAS imbalance

Pulmonary artery resections for lung cancer. When and how?

Resection and reconstruction of the pulmonary artery (PA), whether associated or not to a sleeve resection of the bronchus, allows complete resection of centrally located lung cancer, thus avoiding pneumonectomy. Despite initial concern related to technical difficulties, perioperative management and long term survival, recent studies showed continuous enhancement of the surgical technique and reconstruction materials, reduction of the complication rate and improvement in the survival. This allowed this procedure to gain widespread acceptance in the treatment of lung cancer