F. Pandolfi

The PTOLEMY project aims to develop a scalable design for a Cosmic Neutrino Background (CNB) detector, the first of its kind and the only one conceived that can look directly at the image of the Universe encoded in neutrino background produced in the first second after the Big Bang. The scope of the work for the next three years is to complete the conceptual design of this detector and to validate with direct measurements that the non-neutrino backgrounds are below the expected cosmological signal. In this paper we discuss in details the theoretical aspects of the experiment and its physics goals. In particular, we mainly address three issues. First we discuss the sensitivity of PTOLEMY to the standard neutrino mass scale. We then study the perspectives of the experiment to detect the CNB via neutrino capture on tritium as a function of the neutrino mass scale and the energy resolution of the apparatus. Finally, we consider an extra sterile neutrino with mass in the eV range, coupled to the active states via oscillations, which has been advocated in view of neutrino oscillation anomalies. This extra state would contribute to the tritium decay spectrum, and its properties, mass and mixing angle, could be studied by analyzing the features in the beta decay electron spectrum.

Deep generative models parametrised by neural networks have recently started to provide accurate results in modeling natural images. In particular, generative adversarial networks provide an unsupervised solution to this problem. In this work, we apply this kind of technique to the simulation of particle detector response to hadronic jets. We show that deep neural networks can achieve high fidelity in this task, while attaining a speed increase of several orders of magnitude with respect to traditional algorithms.

The emergence of multidrug-resistant bacteria represents a growing threat to public health, and it calls for the development of alternative antibacterial approaches not based on antibiotics. Here, we propose vertically aligned carbon nanotubes (VA-CNTs), with a properly designed nanomorphology, as effective platforms to kill bacteria. We show, via a combination of microscopic and spectroscopic techniques, the ability to tailor the topography of VA-CNTs, in a controlled and time-efficient manner, by means of plasma etching processes. Three different varieties of VA-CNTs were investigated, in terms of antibacterial and antibiofilm activity, against Pseudomonas aeruginosa and Staphylococcus aureus: one as-grown variety and two varieties receiving different etching treatments. The highest reduction in cell viability (100% and 97% for P. aeruginosa and S. aureus, respectively) was observed for the VA-CNTs modified using Ar and O2 as an etching gas, thus identifying the best configuration for a VA-CNT-based surface to inactivate both planktonic and biofilm infections. Additionally, we demonstrate that the powerful antibacterial activity of VA-CNTs is determined by a synergistic effect of both mechanical injuries and ROS production. The possibility of achieving a bacterial inactivation close to 100%, by modulating the physico-chemical features of VA-CNTs, opens up new opportunities for the design of self-cleaning surfaces, preventing the formation of microbial colonies.

<h2>ABSTRACT</h2> <i>Staphylococcus aureus</i> is not only a common cause of bovine mastitis, but also an agent of food poisoning in humans. In an attempt to determine whether staphylococci causing bovine mastitis could also cause food poisoning, 60 isolates of presumed <i>S</i>. <i>aureus</i> were isolated in the period between March and August 2017 from 3,384 routine, composite, quarter milk samples of individual cows raised on 12 dairy farms in central Italy. Seventeen out of 60 isolates were confirmed as <i>S</i>. <i>aureus</i> after coagulase, thermonuclease, and biochemical tests. These isolates were analyzed by PCR for the presence of the <i>nuc</i>, <i>sea</i>, <i>seb</i>, <i>sec</i>, <i>sed</i>, and <i>see</i> genes. The positive isolates were <i>nuc</i>, 100% (17); <i>sea</i>, 35.29% (6); <i>seb</i>, 5.88% (1); <i>sec</i>, 5.88% (1); <i>sed</i>, 29.41% (5); and <i>see</i>, 47.06% (8). The isolates were also tested with 2 enzyme immunoassay diagnostic kits, one for the screening detection of the production of staphylococcal enterotoxins (SEA, SEB, SEC, SED, SEE) and one for the detection of specific enterotoxin produced by each isolate. Seven out of 17 (41.18%) were enterotoxin producers: 7 produced SEA (41.18%), 1 SEB (5.88%), 1 SEC (5.88%), 5 SED (29.41%), and 6 SEE (35.29%). To further characterize the isolates, they were analyzed by the Kirby Bauer test for susceptibility to 13 antimicrobials (ampicillin, ciprofloxacin, kanamycin, tetracycline, gentamicin, methicillin, nalidixic acid, erythromycin, amoxicillin/clavulanic acid, streptomycin, vancomycin, neomycin, and enrofloxacin), and we detected resistance to ampicillin (52.94%), nalidixic acid (70.59%), erythromycin (5.88%), and amoxicillin/clavulanic acid (17.65%). The isolates were sensitive to the main classes of antimicrobials used for the treatment of bovine subclinical mastitis. The presence of enterotoxin-producing isolates of <i>S</i>. <i>aureus</i> in bovine milk means that a temperature abuse or a breakdown in the thermal treatment of the milk could present a food safety risk, particularly if all enterotoxigenic isolates could potentially produce SEA in milk.

We discuss the consequences of the quantum uncertainty on the spectrum of the electron emitted by the $\beta$-processes of a tritium atom bound to a graphene sheet. We analyze quantitatively the issue recently raised in [Cheipesh et al., Phys. Rev. D 104, 116004 (2021)], and discuss the relevant time scales and the degrees of freedom that can contribute to the intrinsic spread in the electron energy. We perform careful calculations of the potential between tritium and graphene with different coverages and geometries. With this at hand, we propose possible avenues to mitigate the effect of the quantum uncertainty.

Hierarchical fabrics are gaining ever-growing practical interest, thanks to the possibility of combining different properties into a single textile, particularly useful for applications such as high-performance composites showing in situ structural health monitoring capabilities. In this study, homogeneously aligned carbon nanotube forests are directly grown on basalt fabrics by a fast (∼15 min) chemical vapour deposition process without any external catalyst addition providing, for the first time, a highly dense coverage of the underlying substrate. It is demonstrated by transmission electron microscopy that the direct growth of nanotubes on basalt fibres is catalysed by the microstructural segregation of ferrous iron and its subsequent reduction in hydrogen atmosphere to nanocrystalline metallic iron. It is shown that in situ growth requires a pre-treatment etching which can be conducted in mild basic or acidic conditions, achieving optimum performance with an alkaline attack, without compromising the tensile strength of the fibres. Post-growth Raman analysis shows characteristic features associated with high graphitic ordering which turn an intrinsically insulating substrate into an electrically conductive (∼260 S/m) fabric, thus suggesting the possibility to employ the newly engineered hierarchical fabric in all those applications where the combination of good mechanical properties and electrical conductivity is a key requirement.

We present a detailed description of the electromagnetic filter for the PTOLEMY project to directly detect the Cosmic Neutrino Background (CNB). Starting with an initial estimate for the orbital magnetic moment, the higher-order drift process of E×B is configured to balance the gradient-B drift motion of the electron in such a way as to guide the trajectory into the standing voltage potential along the mid-plane of the filter. As a function of drift distance along the length of the filter, the filter zooms in with exponentially increasing precision on the transverse velocity component of the electron kinetic energy. This yields a linear dimension for the total filter length that is exceptionally compact compared to previous techniques for electromagnetic filtering. The parallel velocity component of the electron kinetic energy oscillates in an electrostatic harmonic trap as the electron drifts along the length of the filter. An analysis of the phase-space volume conservation validates the expected behavior of the filter from the adiabatic invariance of the orbital magnetic moment and energy conservation following Liouville’s theorem for Hamiltonian systems.

Abstract The PTOLEMY transverse drift filter is a new concept to enable precision analysis of the energy spectrum of electrons near the tritium β -decay endpoint. This paper details the implementation and optimization methods for successful operation of the filter for electrons with a known pitch angle. We present the first demonstrator that produces the required magnetic field properties with an iron return-flux magnet. Two methods for the setting of filter electrode voltages are detailed. The challenges of low-energy electron transport in cases of low field are discussed, such as the growth of the cyclotron radius with decreasing magnetic field, which puts a ceiling on filter performance relative to fixed filter dimensions. Additionally, low pitch angle trajectories are dominated by motion parallel to the magnetic field lines and introduce non-adiabatic conditions and curvature drift. To minimize these effects and maximize electron acceptance into the filter, we present a three-potential-well design to simultaneously drain the parallel and transverse kinetic energies throughout the length of the filter. These optimizations are shown, in simulation, to achieve low-energy electron transport from a 1 T iron core (or 3 T superconducting) starting field with initial kinetic energy of 18.6 keV drained to &lt; 10 eV (&lt; 1 eV) in about 80 cm. This result for low field operation paves the way for the first demonstrator of the PTOLEMY spectrometer for measurement of electrons near the tritium endpoint to be constructed at the Gran Sasso National Laboratory (LNGS) in Italy.

The ANDROMeDa project, recently funded by the italian ministry of research with a 1M€ grant, has the objective of developing, over the course of the next three years, a novel dark matter (DM) detector based on carbon nanotubes: the ‘dark-PMT’. Such a detector would be sensitive to DM-electron recoils in the eV energy range, and could have world-leading sensitivity for DM masses below 30 MeV with an exposure of only 1g⋅year. Significant R&D is needed to produce carbon nanotubes with ideal properties for a DM target. In particular two by-products of synthesis (non-aligned crust layer and the sub-μm ‘waviness’) are expected to reduce electron transmission probability, and therefore need to be minimized. This will be done via a precise tuning of the evaporation and growth parameters, and of post-growth plasma etching.

We propose to achieve the proof-of-principle of the PTOLEMY project to directly detect the Cosmic Neutrino Background (CNB). Each of the technological challenges described in [1,2] will be targeted and hopefully solved by the use of the latest experimental developments and profiting from the low background environment provided by the LNGS underground site. The first phase will focus on the graphene technology for a tritium target and the demonstration of TES microcalorimetry with an energy resolution of better than 0.05 eV for low energy electrons. These technologies will be evaluated using the PTOLEMY prototype, proposed for underground installation, using precision HV controls to step down the kinematic energy of endpoint electrons to match the calorimeter dynamic range and rate capabilities. The second phase will produce a novel implementation of the EM filter that is scalable to the full target size and which demonstrates intrinsic triggering capability for selecting endpoint electrons. Concurrent with the CNB program, we plan to exploit and develop the unique properties of graphene to implement an intermediate program for direct directional detection of MeV dark matter [3,4]. This program will evaluate the radio-purity and scalability of the graphene fabrication process with the goal of using recently identified ultra-high radio-purity CO2 sources. The direct detection of the CNB is a snapshot of early universe dynamics recorded by the thermal relic neutrino yield taken at a time that predates the epochs of Big Bang Nucleosynthesis, the Cosmic Microwave Background and the recession of galaxies (Hubble Expansion). Big Bang neutrinos are believed to have a central role in the evolution of the Universe and a direct measurement with PTOLEMY will unequivocally establish the extent to which these predictions match present-day neutrino densities.

The ANDROMeDa project, recently funded by the Italian ministry of research with a 1M€ grant, aims to develop a novel light dark matter (DM) detector sensitive to DM-electron recoil in a target of vertically-aligned carbon nanotubes: the “dark-PMT”. Thanks to their vanishing density in the direction of the tube axis, carbon nanotubes allow a scattered electron to leave the target without being re-absorbed only if it travels parallel to the tubes. Therefore the detector is expected to have directional sensitivity, a key feature in DM searches. With only 1 g of exposure per year and a careful suppression of the backgrounds, such detector might achieve world-leading sensitivity for DM masses below 30 MeV.

An automated quantitative study of the alignment of vertically aligned carbon nanotubes (VA-CNTs) from scanning electron microscopy (SEM) images has been demonstrated. It is based on the fact that the image gradient (directional change in intensity or color) at every pixel in the image contains the information about the anisotropy at that particular pixel i.e., the local alignment is maintained in the orthogonal direction to the gradient. Structure tensor metrics are formulated demonstrating to be able to summarize the distribution of gradient directions within the neighborhood of any pixel within a two-dimensional domain (surface). An image analysis is presented that evaluates the alignment in desired regions of interest (ROIs) in SEM images of VA-CNTs. This method has been exploited to study the alignment of two different kinds of VA-CNTs: one grown via the thermal chemical vapor deposition (T-CVD) method and the second synthesized via the plasma enhanced chemical vapor deposition (PE-CVD) method.

The PTOLEMY experiment aims at detecting the cosmic neutrino background, generated ap- proximately one second after the Big Bang, in accordance with Standard Cosmology. Given the extremely low energy of these neutrinos, reliable experimental detection can be accomplished through neutrino captures on beta-unstable nuclides, eliminating the need for a specific energy threshold. Tritium implanted on a carbon-based nanostructure emerges as a promising candi- date among the various isotopes due to its favorable cross-section and low-endpoint energy. The Ptolemy collaboration plans to integrate a solid-state tritium source with a novel compact electro- magnetic filter, based on the dynamic transverse momentum cancellation concept. This filter will be employed in conjunction with an event-based preliminary radio-frequency preselection. The measurement of neutrino mass and the exploration of light sterile neutrinos represent additional outcomes stemming from the Ptolemy experiment’s physics potential, even when utilizing smaller or intermediate-scale detectors. To finalize the conceptualization of the detector, a demonstrator prototype will be assembled and tested at LNGS in 2024. This prototype aims at addressing the challenging aspects of the Ptolemy experiment.

Though their imprint upon the CMB and large-scale structure of the universe remains to this day, Big Bang relic neutrinos (the C𝜈B) have never been directly observed. This remains an outstanding test of the Standard Model in CDM cosmology and would provide the earliest picture of the universe at only one second after the Big Bang. PTOLEMY aims to make the first direct observation of the C𝜈B by resolving the 𝛽-decay endpoint of atomic tritium. The concept relies upon amassing a target of atomic tritium, developing RF-based trigger and tracking, an EM transverse drift filter, and a cryogenic micro-calorimeter - each of which present novel R&D challenges. A prototype will soon be based at Gran Sasso National Laboratory. Intermediate measurements will be made of the lowest neutrino mass ahead of C𝜈B physics runs set to begin in the 2030s.

Directional detection of Dark Matter (DM) particles could be accomplished by studying either ion or electron recoils in large arrays of parallel carbon nanotubes. For instance, a MeV mass DM particle could scatter off a lattice electron, resulting in the transfer of sufficient energy to eject the electron from the nanotube surface. The electron can eventually be detected whenever an external electric field is added to drive it from the open ends of the array. This detection scheme would offer an anisotropic response and could be used to select an orientation of the target with respect to the DM wind. A compact sensor, in which the cathode element is substituted with a dense array of parallel carbon nanotubes, could serve as the basic detection unit which - if adequately replicated - would allow to explore a significant region of light DM mass and cross-section. A similar detection scheme could be used to detect DM particles with mass in the GeV range scattering off the surface of a CNT and ejecting a carbon ion. We report about the Monte Carlo simulations of such a system and the R&D towards a detector prototype.

Cerium-doped Lutetium-Yttrium Oxyorthosilicate (LYSO:Ce)is one of the most widely used Cerium-doped Lutetium based scintillation crystals. Initially developed for medical detectors it rapidly became attractive for High Energy Particle Physics (HEP) applications, especially in the frame of high luminosity particle colliders. In this paper, a comprehensive and systematic study of LYSO:Ce ($[Lu_{(1-x)}Y_x]_2SiO_5$:$Ce$) crystals is presented. It involves for the first time a large number of crystal samples (180) of the same size from a dozen of producers.The study consists of a comparative characterization of LYSO:Ce crystal products available on the market by mechanical, optical and scintillation measurements and aims specifically, to investigate key parameters of timing applications for HEP.

The authors studied CD40 ligand (CD40L) expression and interleukin‐10 (IL‐10) production in 16 patients with common variable immunodeficiency (CVI). Mean CD40L expression, determined by using cytofluorimetry, and measured as the mean fluorescence intensity following stimulation of peripheral blood mononuclear cells (PBMC) with phorbol myristate acetate (PMA) and calcium ionophore in 12 patients, was comparable to that of controls. However, three CVI patients showed fluorescence intensity in stimulated cells below 2 standard deviations of normal donors’ mean and two other patients had only a slight increase of stimulated versus unstimulated cells (&lt;10 channels). IL‐10 production after stimulation of PBMC with both anti‐CD3 or anti‐CD3 plus PMA gave similar results in CVI patients and normal controls. In vitro stimulation of PBMC with anti‐CD40 and various combinations of cytokines (IL‐2, IL‐4 and IL‐10) induced IgG production above 100 ng/ml in one CVI patient out of 13 tested. The data suggest that alterations of IL‐10 production are unlikely to play a major role in the pathogenesis of impaired IgG production in most CVI patients. CD40L appears to be normally expressed in two thirds of CVI patients, but it may be functionally defective.

The theoretical foundations of the Standard Model of elementary particles relies on the existence of the Higgs boson, a particle which has been revealed for the first time by the experiments run at th

A novel geometry for a sampling calorimeter employing inorganic scintillators as an active medium is presented. To overcome the mechanical challenges of construction, an innovative light collection geometry has been pioneered, that minimises the complexity of construction. First test results are presented, demonstrating a successful signal extraction. The geometry consists of a sampling calorimeter with passive absorber layers interleaved with layers of an active medium made of inorganic scintillating crystals. Wavelength-shifting (WLS) fibres run along the four long, chamfered edges of the stack, transporting the light to photodetectors at the rear. To maximise the amount of scintillation light reaching the WLS fibres, the scintillator chamfers are depolished. It is shown herein that this concept is working for cerium fluoride (CeF3) as a scintillator. Coupled to it, several different types of materials have been tested as WLS medium. In particular, materials that might be sufficiently resistant to the High- Luminosity Large Hadron Collider radiation environment, such as cerium-doped Lutetium- Yttrium Orthosilicate (LYSO) and cerium-doped quartz, are compared to conventional plastic WLS fibres. Finally, an outlook is presented on the possible optimisation of the different components, and the construction and commissioning of a full calorimeter cell prototype is presented.

We report on the characterization of the response of windowless silicon avalanche photo-diodes to electrons in the 90-900 eV energy range. The electrons were provided by a monoenergetic electron gun present in the LASEC laboratories of University of Roma Tre. We find that the avalanche photo-diode generates a current proportional to the current of electrons hitting its active surface. The gain is found to depend on the electron energy Ee, and varies from 2.147 ± 0.027 (for Ee = 90 eV) to 385.8 ± 3.3 (for Ee = 900 eV), when operating the diode at a bias of Vapd = 350 V. This is the first time silicon avalanche photo-diodes are employed to measure electrons with Ee < 1 keV.

Abstract We report on an apparatus able to measure the absolute detection efficiency of a detector for electrons in the 30–900 eV range. In particular, we discuss the characterisation of a two-stage chevron microchannel plate (MCP). The measurements have been performed in the LASEC laboratory at Roma Tre University, whit a custom-made electron gun. The very good stability of the beam current in the fA range, together with the picoammeter nominal resolution of 0.01 fA, allowed the measurement of the MCP absolute efficiency ε . We found an <?CDATA $\epsilon = (0.489 \pm 0.003)$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ϵ</mml:mi> <mml:mo>=</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:mn>0.489</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.003</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> with no evident energy dependence. We fully characterised the MCP pulse shape distribution, which is quasi-Gaussian with a well visible peak above the noise level. We measured a 68 <?CDATA $\%$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> variation of the average pulse height between 30 and 500 eV. Furthermore, with a deeper analysis of the pulse shape, and in particular of the correlation between pulse height, area and width, we found a method to discriminate single- and multi- electron events occurring within a 10 ns time window.

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with heavy absorber plates, and read out by wavelength-shifting (WLS) fibers is being studied as a calorimeter option for detectors at the upgraded High-Luminosity LHC (HL-LHC) collider at CERN. A prototype has been exposed to electron beams of different energies at the INFN Frascati (Italy) Beam Test Facility. This paper presents results from the studies performed on the prototype, such as signal amplitudes, light yield and energy resolution.

A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype׳s energy resolution.

The PTOLEMY project aims to develop a scalable design for a Cosmic Neutrino Background (CNB) detector, the first of its kind and the only one conceived that can look directly at the image of the Universe encoded in neutrino background produced in the first second after the Big Bang. The scope of the work for the next three years is to complete the conceptual design of this detector and to validate with direct measurements that the non-neutrino backgrounds are below the expected cosmological signal. In this paper we discuss in details the theoretical aspects of the experiment and its physics goals. In particular, we mainly address three issues. First we discuss the sensitivity of PTOLEMY to the standard neutrino mass scale. We then study the perspectives of the experiment to detect the CNB via neutrino capture on tritium as a function of the neutrino mass scale and the energy resolution of the apparatus. Finally, we consider an extra sterile neutrino with mass in the eV range, coupled to the active states via oscillations, which has been advocated in view of neutrino oscillation anomalies. This extra state would contribute to the tritium decay spectrum, and its properties, mass and mixing angle, could be studied by analyzing the features in the beta decay electron spectrum.

Carbon nanostructures offer exciting new possibilities in the detection of light dark matter.A dark matter particle with mass between 1 MeV and 1 GeV scattering off an electron in the carbon would transfer sufficient energy to extract the electron from the lattice.In 2D materials, such as graphene or carbon nanotubes, these electrons would be released directly into the vacuum, avoiding their re-absorption in the medium.We present two novel detector concepts: a 'Graphene-FET' design, based on graphene sheets, developed at Princeton University; and a 'Dark-PMT' based on aligned carbon nanotubes, developed in University of Rome Sapienza.We discuss their light dark matter discovery potential, the status of the RD, and the recent commissioning of a state-of-the-art carbon nanotube growing facility in Rome.

The ANDROMeDa (Aligned Nanotube Detector for Research On MeV Dark matter) project aims to develop a novel Dark Matter detector based on carbon nanotubes: the “Dark-PMT”. The detector is designed to be sensitive to dark matter particles with mass between 1 MeV and 1 GeV. The detection scheme is based on dark matter-electron scattering inside a target made of vertically-aligned carbon nanotubes. Vertically-aligned carbon nanotubes have reduced density in the direction of the tube axis, therefore the scattered electrons are expected to leave the target without being re-absorbed only if their momentum has a small enough angle with that direction, which is what happens when the tubes are parallel to the dark matter wind. This grants directional sensitivity to the detector, a unique feature in this dark matter mass range.

Highly aligned multi-wall carbon nanotubes were investigated with scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) before and after bombardment performed using noble gas ions of different masses (argon, neon and helium), in an ultra-high-vacuum (UHV) environment. Ion irradiation leads to change in morphology, deformation of the carbon (C) honeycomb lattice and different structural defects in multi-wall carbon nanotubes. One of the major effects is the production of bond distortions, as determined by micro-Raman and micro-X-ray photoelectron spectroscopy. We observe an increase in sp3 distorted bonds at higher binding energy with respect to the expected sp2 associated signal of the carbon 1s core level, and increase in dangling bonds. Furthermore, the surface damage as determined by the X-ray photoelectron spectroscopy carbon 1s core level is equivalent upon bombarding with ions of different masses, while the impact and density of defects in the lattice of the MWCNTs as determined by micro-Raman are dependent on the bombarding ion mass; heavier for helium ions, lighter for argon ions. These results on the controlled increase in sp3 distorted bonds, as created on the multi-wall carbon nanotubes, open new functionalization prospects to improve and increase atomic hydrogen uptake on ion-bombarded multi-wall carbon nanotubes.

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (<10%/E). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors׳ forward regions during the high luminosity phase of LHC.

The High-Luminosity phase of the Large Hadron Collider at CERN (HL-LHC) poses stringent requirements on calorimeter performance in terms of resolution, pileup resilience and radiation hardness. A tungsten-CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sampling calorimeter is a possible option for the upgrade of current detectors. A prototype, read out with different types of wavelength-shifting fibers, has been built and exposed to high energy electrons, representative for the particle energy spectrum at HL-LHC, at the CERN SPS H4 beam line. This paper shows the performance of the prototype, mainly focussing on energy resolution and uniformity. A detailed simulation has been also developed in order to compare with data and to extrapolate to different configurations to be tested in future beam tests. Additional studies on the calorimeter and the R&D projects ongoing on the various components of the experimental setup will be also discussed.

Jets represent a long withstanding challenge for both theoretical and experimental physics. Because of their composite nature, they necessitate of a clustering algorithm to be defined, and their interaction with the detector will vary significantly on a jet-by-jet basis, depending each jet’s composition. The instrinsic difficulty in experimentally determining a jet’s particle composition translates in an uncertainty on the measurement of the jet’s energy scale, and therefore in the necessity of additional calibration procedures, specific for jets. In the first part of this chapter we will describe the jet energy scale problematic, and explain the related challenges from an experimental point of view. We will show how sophisticated jet reconstruction techniques, such as the CMS full event reconstruction known as the Particle Flow, may significantly improve jet reconstruction performance. Section 3.3 is dedicated to illustrating the jet calibration scheme employed in CMS, and showing the results on the measurement of the jet energy scale and resolution in proton-proton collisions. Finally, Sect. 3.5 demonstrates how detailed information on jet particle composition can give insight on the nature of the parton originating the jet.

A novel geometry for a sampling calorimeter employing inorganic scintillators as an active medium is presented. To overcome the mechanical challenges of construction, an innovative light collection geometry has been pioneered, that minimises the complexity of construction. First test results are presented, demonstrating a successful signal extraction. The geometry consists of a sampling calorimeter with passive absorber layers interleaved with layers of an active medium made of inorganic scintillating crystals. Wavelength-shifting (WLS) fibres run along the four long, chamfered edges of the stack, transporting the light to photodetectors at the rear. To maximise the amount of scintillation light reaching the WLS fibres, the scintillator chamfers are depolished. It is shown herein that this concept is working for cerium fluoride (CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) as a scintillator. Coupled to it, several different types of materials have been tested as WLS medium. In particular, materials that might be sufficiently resistant to the High-Luminosity Large Hadron Collider radiation environment, such as cerium-doped Lutetium-Yttrium Orthosilicate (LYSO) and cerium-doped quartz, are compared to conventional plastic WLS fibres. Finally, an outlook is presented on the possible optimisation of the different components, and the construction and commissioning of a full calorimeter cell prototype is presented.

Since the discovery of the top quark, which took place in 1995 at the Tevatron collider at Fermilab, the Higgs boson may be considered the last missing piece of the Standar Model. Its search has been undertaken at the LEP and Tevatron colliders, but no evidence of its existence was found, at the energies which were probed. The mass of the Higgs boson is an unconstrained parameter of the theory, therefore a collider which is able to explore vast energy ranges is cardinal for its discovery. The Large Hadron Collider at CERN has been designed with the aim of providing conclusive scientifical results regarding the existence of the Higgs boson. This chapter provides a quick but accurate introduction to the current theoretical panorama in elementary particle physics: we will describe the Standard Model, the motivations which bring to the introduction of the Higgs mechanism, and its consequences. We will then summarize the experimental limits on the Higgs boson mass previous to the Large Hadron Collider, and introduce the \(\mathrm{H}\rightarrow \mathrm{ZZ} \rightarrow \ell ^{+}\ell ^{-}\mathrm{q}\bar{\mathrm{q}}\) decay channel, and the role it plays in the search for this elusive particle.

The strategy adopted by the CMS collaboration is to search for the Standard Model Higgs boson in a total of 173 mass points across the $$114-600$$ GeV invariant mass range. This analysis has limited statistical power for masses below the $$ZZ$$ production threshold, therefore we will focus on the high-mass range $$200-600$$ GeV, which comprises of a total of 73 mass points. In this chapter we will describe how we model the presence of a hypothetical Higgs signal, and the statistical methods adopted to convert the analysis outcome into a statement on the Higgs boson’s existence.

We have presented a search for a heavy Higgs boson in the decay channel

This chapter treats the possible sources of systematic uncertainties associated with this measurement. As the background is estimated directly on the data, as shown in the previous chapter, and therefore has a separate uncertainty, here we study only effects which could affect signal efficiency.

The following chapter details the event selection that is employed in the analysis. Section 4.1 reports the analyzed datasets, both of data and simulated events, and Sect. 4.2 lists the preselection requirements which events are required to satisfy. Subsequent sections investigate means of background discrimination, and define the final analysis event selection procedure. Section 4.6 proceeds to optimize the selection requirements. Finally, the expected signal and background yields are reported in Sect. 4.8, and the means of background estimation employed on the data is shown in Sect. 4.9.

This chapter is dedicated to the description of the experimental apparatus which made these measurements possible. Section 2.1 describes the Large Hadron Collider, the accelerator which provided 7 TeV proton-proton collisions which were analysed in this thesis. The collisions were reconstructed with the Compact Muon Solenoid (CMS) detector, to which Sect. 2.2 is dedicated to. The two final sections of this chapter illustrate the lepton reconstruction techniques adopted in CMS.

Searches for resonances in final states with leptons and photons have always been a powerful tool for discovery in high energy physics. We present here the latest results from the ATLAS and CMS experiments, based on up to 36.1 fb$^{-1}$ of 13 TeV proton-proton collisions produced at the Large Hadron Collider. Detailed results on single lepton, dilepton, diphoton and Z$γ$ resonances are included.

We present the results of searches for R-parity-conserving Supersymmetry in all-hadronic final states based on a dataset of 12.9 fb -1 of 13 TeV proton-proton collisions recorded in 2016 by the CMS experiment at LHC.The results of three searches (H T /H miss T , M T2 and α T ) are detailed.The backgrounds to these searches are estimated directly in the data.No significant excess is recorded with respect to the background estimations.Exclusion limits are set, at 95% confidence level, on simplified models.Depending on the model, gluino masses are excluded up to 1.7 TeV, top squarks up to 900 GeV, and neutralinos (here considered the lightest Supersymmetric particle) up to 1.2 TeV.

The results of the commissioning of the Particle Flow on 900 GeV collisions recorded by CMS are shown. The Particle Flow is an event reconstruction technique which combines all CMS subdetectors into the creation of particle candidates, and improves jet and missing transverse-energy reconstruction performance.

To meet the harsh radiation and pile-up environment of HL-LHC, CMS will add a timing layer between the tracker and the calorimeters. The detector will be called MIP Timing Detector (MTD) and will have a target resolution of 30-40 ps at the beginning of data-taking, degrading to only 40-60 ps at the end of operations. The MTD will be comprised of two detectors: a Barrel Timing Layer (BTL) made of scintillating LYSO crystal bars coupled with SiPMs, and an Endcap Timing Layer (ETL) made of Low-Gain Avalanche Diodes (LGADs). Successful R&D campaigns have been carried out, proving that the required performance is achievable with the chosen technologies.

Following up on the work of C. R. Sun1 , we are investigating the performance of homogeneous, high-resistivity, silicon crystals as detectors for minimum-ionizing particles. In particular we are considering such a detector for use in conjunction with the operation of a hydrogen bubble chamber. Such devices would have the advantages of good spatial resolution, compactness, and stable performance in high magnetic fields. Operation would be at liquid nitrogen temperature. The detectors are cut as 2.5 mm thick wafers from an n-type ingot ~1.8 cm in diameter and with a typical resistivity of 1000 to 3000 ohm-cm. Nickel ohmic contacts are applied to each side of the wafer by a chemical plating process. In order to keep the dark current to a minimum, we try to raise the resistivity of the prospective detector close to the intrinsic level. This is accomplished by exposing the silicon, at 25°C, to a high flux of γ radiation from a Co60 source. Typically, after an exposure of 1.5 × 107 roentgens the silicon will have a resistivity of 4.0 × 106 ohm-cm at liquid nitrogen temperature (78°K). Using a charge sensitive amplifier, we observe pulse rise times of the order of 150 nanoseconds and signal to noise ratios greater than 10. There exists a "critical exposure level," C.E.L., for the γ irradiation. For radiation dosages greater than the C.E.L., the detector performance deteriorates. It seems possible to determine the C.E.L. conveniently by checking the detector resistivity at 25°C; for when the C.E.L.

Implementation details and optimization methods are presented for operation of the PTOLEMY transverse drift electromagnetic filter in low field. Low field operation introduces new challenges for tritium endpoint electron transport. The growth of the cyclotron radius in low field conditions puts a ceiling on filter performance relative to fixed filter dimensions. Furthermore, low pitch angle trajectories are dominated by parallel motion along the magnetic field lines and introduce non-adiabatic conditions and curvature drift. Starting with a first realization of the PTOLEMY magnetic field with an iron return-flux magnet, low field effects on endpoint electron transport are investigated. The parallel and transverse kinetic energies are drained simultaneously throughout the length of the filter using a three potential well configuration, with the center flanked by two side wells. These optimizations are shown to achieve low energy electron transport from a 1-3 T starting field. This result for low field operation paves the way for the first demonstrator of the PTOLEMY electromagnetic filter for the measurement of electrons near the tritium endpoint.

Abstract We present the ‘dark-PMT’, a novel detector concept based around a target made of vertically-aligned carbon nanotubes. The detector is sensitive to electron recoils induced by sub-GeV dark matter, and is expected to have directional sensitivity and to be unaffected by thermal noise, even at room temperature. The key feature is that nanotubes are made of graphene, which is a two-dimensional material: therefore, if a dark matter particle transfers enough energy to an electron in the carbon lattice to overcome the work function (4.7 eV), the electron will be ejected directly into the vacuum. Because of the strong density anisotropy of nanotubes, the electrons will be capable of leaving the target, without being reabsorbed, if travelling in the direction of the tube axes. The electrons will then be accelerated, and reach an energy of 5 keV before hitting an electron sensor. We report on the most recent advancements towards the construction of a dark-PMT: a novel, state-of-the-art facility for nanotube synthesis has been recently installed in Rome, and it is being used to produce high-quality nanotubes; and detailed characterizations of silicon sensors with keV electrons have been performed.