Dissertations / Theses on the topic 'High Energy Physics'

The future of new physics searches at the LHC will be to look for hadronic signals with jets. In order to distinguish a hadronic signal from its background, it is important to develop advanced collider physics techniques that make accurate theoretical predictions. This work centers on phenomenological and formal studies of Quantum Chromodynamics (QCD), including resummation of hadronic observables using Soft Collinear Effective Theory (SCET), calculating anomalous dimensions of multi-Wilson line operators in AdS, and improving jet physics analysis using multiple event interpretations.
Physics

La presente dissertazione descrive il design, la caratterizzazione e il funzionamento di sistemi elettronici per esperimenti di Fisica delle particelle (LHCb) e Fisica del neutrino (CUORE e CUPID). A partire dal 2019, l'esperimento LHCb presso l'acceleratore LHC sarà aggiornato per lavorare a luminosità più elevata e molti dei suoi rivelatori dovranno essere riprogettati. Il rivelatore RICH, in particolare, dovrà adottare un sistema optoelettronico totalmente nuovo. Lo sviluppo di questo sistema ha già raggiunto una fase avanzata e diversi test eseguiti su fascio hanno permesso di verificare le prestazioni dell'intero sistema. Per migliorare la stabilità, il filtraggio e la regolazione delle tensioni di alimentazione del circuito di front-end, è stato sviluppato un regolatore lineare a basso dropout e resistente alla radiazione, denominato ALDO. Sono qui presentate le strategie di progetto, la misurazione delle prestazioni e i risultati delle campagne di irraggiamento di questo dispositivo. Nel campo della fisica del neutrino, grandi array di macrobolometri, come quelli adottati dall'esperimento CUORE e dal suo futuro aggiornamento CUPID, offrono delle caratteristiche uniche per lo studio del doppio decadimento beta senza neutrini. Il loro funzionamento richiede particolari strategie progettuali nel sistema elettronico di lettura, che è qui descritto nella sua interezza. Sono anche presentate nel dettaglio le misure di qualifica e ottimizzazione dei parametri di funzionamento di tutto il sistema, oltre che l'integrazione all'interno dell'area sperimentale. Infine sono presentati gli aggiornamenti di alcuni sottosistemi elettronici in vista della fase finale di CUPID.
The present dissertation describes design, qualification and operation of several electronic instrumentations for High Energy Particle Physics experiments (LHCb) and Neutrino Physics experiments (CUORE and CUPID). Starting from 2019, the LHCb experiment at the LHC accelerator will be upgraded to operate at higher luminosity and several of its detectors will be redesigned. The RICH detector will require a completely new optoelectronic readout system. The development of such system has already reached an advanced phase, and several tests at particle beam facilities allowed to qualify the performance of the entire system. In order to achieve a higher stability and a better power supply regulation for the front-end chip, a rad-hard low dropout linear regulator, named ALDO, has been developed. Design strategies, performance tests and results from the irradiation campaign are presented. In the Neutrino Physics field, large-scale bolometric detectors, like those adopted by CUORE and its future upgrade CUPID, offer unique opportunities for the study of neutrinoless double beta decay. Their operation requires particular strategies in the readout instrumentation, which is described here in its entirety. The qualification and optimization of the working parameters as well as the integration of the system in the experimental area are also thoroughly discussed, together with the latest upgrades of two electronic subsystems for the future CUPID experiment.

Gases comprised of atomic clusters have in the past been shown to exhibit extremely strong absorption of high-intensity laser pulses. By using this target medium, it is possible to use laser systems with only modest energies to create High Energy Density Plasmas. Not only are the plasmas created in this way of interest in themselves, but when properly designed, these experiments can be used as a platform for Laboratory Astrophysics studies of radiative blast waves. This thesis describes experiments which investigate the evolution of radiative blast waves, the interaction of relativistic laser pulses with large atomic clusters and the nature of the post laser-cluster interaction upstream medium into which the shock propagates. Experiments were carried out to diagnose the properties of the upstream medium into which radiative shocks launched by the laser-cluster interaction propagate. This experiment was conducted using the Blackett Laboratory Laser Consortium Nd:Glass laser system with a novel perpendicular heating beam geometry. By introducing a time delay between the perpendicular beams, it was possible to track the propagation of a ballistic cluster disassemble wave. This wave was shown to be the product of ~200 keV ions ejected by the initial laser cluster-interaction. Also discussed in this thesis are the results of the first laser-cluster experiment to be conducted on the Central Laser Facility's Astra-Gemini system. Here the interaction of large atomic clusters with relativistic laser pulses is investigated. X-Ray pinhole camera images have been captured of the early time plasma created by the laser-clusters interaction. For the first time the absorption properties of large atomic clusters irradiated by a femtosecond high energy, ~14 J, laser pulse have been studied. Furthermore, the temporal evolution of radiative blast waves launched from the laser-cluster interaction is described. In the past the Vulcan laser system at RAL was used to launch blast waves which displayed velocity domain oscillations driven by the radiation emitted by the blast wave. This instability has again been observed in the work reported here and the threshold for onset has been investigated.

Integrated Circuits are used in most people’s lives in the modern societies. An important branch of research and technology is focused on Integrated Circuit (IC) design, fabrication, and their efficient applications; moreover most of these activities are about commercial productions with applications in ambient environment. However the ICs play very important role in very advance research fields, as Astronomy or High Energy Physics experiments, with absolutely extreme environments which require very interdisciplinary research orientations and innovative solutions. For example, the Fast TracKer (FTK) electronic system, which is an important part of triggering system in ATLAS experiment at European Organization for Nuclear Research (CERN), in every second of experiment selects 200 interesting events among 40 millions of total events due to collision of accelerated protons. The FTK function is based on ICs which work as Content Addressable Memory (CAM). A CAM compares the income data with stored data and gives the addresses of matching data as an output. The amount of calculation in FTK system is out of capacity of commercial ICs even in very advanced technologies, therefore the development of innovative ICs is required. The high power consumption due to huge amount of calculation was an important limitation which is overcome by an innovative architecture of CAM in this dissertation. The environment of ICs application in astrophysics and High Energy Physics experiments is different from commercial ICs environment because of high amount of radiation. This fact started to get seriously attention after the first “Telstar I” satellite failure because of electronic damages due to radiation effects in space, and opened a new field of research mostly about radiation hard electronics. The multidisciplinary research in radiation hard electronic field is about radiation effects on semiconductors and ICs, deep understanding about the radiation in the extreme environments, finding alternative solutions to increase the radiation tolerance of electronic components, and development of new simulation method and test techniques. Chapter 2 of this dissertation is about the radiation effects on Silicon and ICs. Moreover, In this chapter, the terminologies of radiation effects on ICs are explained. In chapter 3, the space and high energy physics experiments environments, which are two main branches of radiation hard electronics research, are studied. The radiation tolerance in on-chip circuits is achieving by two kinds of methodology: Radiation Hardening By Process (RHBP) and Radiation Hardening By Design (RHBD). RHBP is achieved by changing the conventional fabrication process of commercial ICs. RHBP is very expensive so it is out of budget for academic research, and in most cases it is exclusive for military application, with very restricted rules which make the access of non-military organizations impossible. RHBD with conventional process is the approach of radiation hard IC design in this dissertation. RHBD at hardware level can be achieved in different ways: • System level RHBD: radiation hardening at system level is achieved by algorithms which are able to extract correct data using redundant information. •Architecture level RHBD: some hardware architectures are able to prevent of lost data or mitigate the radiation effects on stored data without interfacing of software. Error Correction Code (ECC) circuits and Dual Interlocked storage CEll (DICE) architecture are two examples of RHBD at architecture level. • Circuit level RHBD: at circuit level, some structures are avoided or significantly reduced. For example, feedback loops with high gain are very sensitive to radiation effects. • Layout level RHBD: there are also different solutions in layout design level to increase the radiation tolerance of circuits. Specific shapes of transistor design, optimization of the physical distance between redundant data and efficient polarization of substrate are some techniques commonly used to increase significantly the radiation tolerance of ICs. An innovative radiation hard Static Random Access Memory (SRAM), designed in three versions, is presented in chapter 4. The radiation hardening is achieved by RHBD approach simultaneously at architecture, circuit and layout levels. Complementary Metal-Oxide-Semiconductor (CMOS) 65 nm is the technology of design and the prototype chip is fabricated at Taiwan Semiconductor Manufacturing Company (TSMC). Chapter 5 is about the development of simulation models that can help to predict the radiation effect in the behavior of SRAM block. The setup system developed to characterize the radiation hard SRAM prototype chip is presented in Chapter 5. The setup system gives the possibility of testing the prototype exposed under radiation in a vacuum chamberand regular laboratory environment. Chapter 6 is about the contribution of this dissertation on FTK project and the conclusion of all research activities is shown in the final part of this dissertation. The research activities of this dissertation in supported by Italian National Institute for Nuclear Physics (INFN) as part of CHIPIX65 project and RD53 collaboration at CERN.

This thesis is devoted to the study of phenomenological consequences of theoretical models of Quantum Gravity. In particular, this work is focused on the study of possible violations of Lorentz invariance, which may arise if, owing to quantum gravity effects, the high-energy structure of the spacetime is different from the smooth, continuous one we are used to in our low-energy world. After a brief description of the most widely known models accounting for Lorentz invariance violations, particular focus will be given to astrophysical tests of Lorentz invariance. These are motivated by the fact that some astrophysical objects are able to accelerate particles to extremely high energies, unreachable to terrestrial experiments. This consideration naturally leads us to look at the radiation of the Crab Nebula, one of the most powerful objects in our Galaxy. We first understand how the violation of Lorentz invariance affects the physical processes at the basis of the production of electromagnetic radiation by this object. Then, we compare our prediction for the Lorentz violating spectrum to observational data, exploiting the vast multi-wavelength information on the Crab Nebula radiation. Furthermore, we take advantage of the recent development of new technology to improve on our analysis of the Crab Nebula radiation by extending our research to the effects of Lorentz violation onto hard X-ray polarization. After this investigation we shall move to study the physics of cosmic rays, the most energetic particles ever experienced on Earth. Our interest in this physics is twofold: on the one hand, we want to understand more about their properties and their propagation. To this aim, we develop a new model of propagation for cosmic rays in our Galaxy, exploiting as much as possible of the multi-channel information available at present. On the other hand, according to the multi-channel perspective, we try to understand the consequences of Lorentz symmetry violation on the properties of ultra-highenergy cosmic rays.

In this thesis I discuss different aspects of high energy resummation in Quantum Chromo-Dynamics and its relevance for precision physics at hadron colliders. The high energy factorisation theorem is presented and discussed in detail, emphasizing its connections with standard factorisation of collinear singularities. The DGLAP and the BFKL equations are presented and leading twist duality relations between the evolution kernels are discussed. High energy factorisation is used to compute resummed coefficient functions for hadronic processes relevant for LHC phenomenology. The case of heavy flavour production is analysed in some detail and results already present in the literature are confirmed. High energy effects can play an important role for such cross sections which are to be used as standard candles at the LHC, such as W/Z production. To this purpose Drell-Yan processes are studied in high energy factorisation. The inclusive cross section for Higgs boson production via gluon-gluon fusion is analysed both in the heavy top limit and for finite values of the top mass. The different high energy behaviour of the two cases is studied, showing explicitly that the full theory exhibits single high energy logarithms in contrast to the infinite top mass limit. The correct high energy behaviour of the partonic cross section is then combined to the NNLO calculation performed in the heavy top limit, in order to obtain an improved coefficient function. Finite top mass effects at high energy on the hadronic cross section are moderate. As far as parton evolution is concerned, an approximate expression for the NNLO contribution to the kernel of the BFKL equation is computed exploiting running coupling duality relations between DGLAP and BFKL. This result includes all collinear and anticollinear singular contributions and it is computed in various factorisation schemes. The collinear approximation is tested against the known LO and NLO kernels with the discrepancy being at the percent level. Therefore the approximate NNLO contribution is likely to be close to the as yet unknown complete result in the region relevant at leading twist.

It was recently proposed that modifications to physics at trans-Planckian energies could lead to a non-adiabatic evolution of the scalar fluctuations responsible for the temperature anisotropy of the cosmological microwave background. If such a possibility was to be confirmed, it would provide us the first possibility to ever get experimental measurements of the physics near the Planck scale. This work investigates the physicality of such non-adiabatic evolutions, by avoiding the introduction of any exotic physics, by working well below the Planck scale. Simple 'hybrid-like' models of inflation composed of an inflaton field coupled to another heavy scalar will be used. It will be shown that small oscillations in the heavy scalar field can generate a non-adiabatic evolution of the inflationary vacuum leading to new features in the power spectrum that could eventually be observed. The naturalness of this non-adiabaticity is also studied, leading to a constraint about the maximum duration of inflation if these effects are to be big enough to ever be detectable.

Il seguente elaborato di tesi è svolto nel contesto di una accordo tra le organizzazioni INAF e CERNOpenLab per esplorare le possibilità computazionali dell’architettura IBM POWER nel contesto della fisica delle alte energie. Nel primo capitolo si illustrano le sfide che la prossima generazione di esperimenti porranno alla comunità scientifica. Tra queste sfide, è evidenziata la grande richiesta di tempo di calcolo dei metodi Monte Carlo per il Particles Transport. Anche un piccolo incremento di velocità delle simulazioni farebbe risparmiare alla comunità scientifica centinaia di migliaia di euro all’anno. Viene quindi descritto il software Geant4 e presentata la sua evoluzione, il progetto GeantV. Lo scopo di quest’ultimo è sfruttare completamente le caratteristiche dei processori moderni, come l’architettura IBM POWER di cui vengono delineate le caratteristiche principali. Nel secondo capitolo si porta a termine la validazione scientifica di un insieme di modelli fisici di Geant4 sulla CPU POWER8E, nel contesto della missione e-ASTROGAM. Nel terzo capitolo vengono confrontate le velocità delle CPU POWER8NVL e Xeon E5-2697 misurando il tempo di calcolo su di un codice Geant4 di simulazione. Si mostra un problema di efficienza nel test a singolo thread. La causa del problema viene ricondotta all’utilizzo del compilatore GCC. Il problema viene risolto attraverso l’utilizzo del compilatore XL. Lo stesso codice di simulazione viene quindi eseguito in modalità multi thread e viene verificata la scalabità in entrambe le CPU. Nel quarto capitolo, si compilano sull’architettura POWER8NVL, le librerie delle dipendenze software di GeantV, risolvendo gli errori di compilazione incontrati. Infine si compilano le librerie di GeantV come primo passo verso una futura integrazione tra GeantV e l’architettura POWER. Nel capitolo conclusivo, si riassumono i risultati ottenuti e vengono prestantate una serie di possibili strategie per aumentare l’efficienza computazionale del POWER.

This thesis is focused on the development of novel approaches to improve the explainability of Deep Neural Network models in High Energy Physics to reduce the size of a certain model by dropping irrelevant input information. We show that it is possible to reduce the size of a signal-background classification problem by automatically ranking the relative importance of available particle jet input features. Variables are importance-sorted with a decision tree algorithm. The selected features can be used as input quantities for the classification problem at hand. A k-fold cross-validation is applied to raise the confidence in the extracted ranking. On the same line, a new Neural Network layer, called CancelOut, is presented as a tool to reduce the input parameter size by keeping the performance the highest during the training of the model. Both strategies are tested with the case of highly boosted di-jet resonances decaying to two b-quarks, to be selected against an overwhelming QCD background with a Deep Neural network. The data are produced via a pseudo experiment simulation.

With the bare essentials of noncommutative geometry (defined by a spectral triple), we first describe how it naturally gives rise to gauge theories. Then, we quickly review the notion of twisting (in particular, minimally) noncommutative geometries and how it induces a Wick rotation, that is, a transition of the metric signature from euclidean to Lorentzian. We focus on comparatively more tractable examples of spectral triples; such as the ones corresponding to a closed Riemannian spin manifold, U(1) gauge theory, and electrodynamics. By minimally twisting these examples and computing their associated fermionic actions, we demonstrate how to arrive at physically relevant actions (such as the Weyl and Dirac actions) in Lorentz signature, even though starting from euclidean spectral triples. In the process, not only do we extract a physical interpretation of the twist, but we also capture exactly how the Wick rotation takes place at the level of the fermionic action.

During my PhD I have been involved in two experiments, LHCb (at CERN) and CUORE (at LNGS). The former is devoted to search of physics beyond the Standard Model. I collaborated to characterize MaPMTs and develop the read-out electronic system. Such equipment will be used for the upgrade of the RICH detector, responsible for the particle identification. CUORE is an experiment searching the neutrinoless double beta decay in tellurium 130. I collaborated to develop and mount the electronic apparatus. The studies on the linear power supply, the slow control communication system and the ultra-precise and ultra-stable pulser board for the bolometer response stabilization, will be described.
During my PhD I have been involved in two experiments, LHCb (at CERN) and CUORE (at LNGS). The former is devoted to search of physics beyond the Standard Model. I collaborated to characterize MaPMTs and develop the read-out electronic system. Such equipment will be used for the upgrade of the RICH detector, responsible for the particle identification. CUORE is an experiment searching the neutrinoless double beta decay in tellurium 130. I collaborated to develop and mount the electronic apparatus. The studies on the linear power supply, the slow control communication system and the ultra-precise and ultra-stable pulser board for the bolometer response stabilization, will be described.

High-energy particle interactions have been of interest to scientists ever since the discovery of cosmic rays early this century. With the realization, almost half a century later, that the prodigious radio emission seen from outer-space is due in part to these particles gyrating in cosmic magnetic fields, a new field was born which joined physics and astronomy. By studying the interaction signatures of these particles, we can gain a better understanding of the microphysics of their motion and collisions, as well as the macrophysics governing the vast and distant astrophysical objects which host them. The Galactic center is very important for this burgeoning field. Because of its proximity, years of detailed observations in particularly the radio and infrared wavebands have provided us with a good picture of what the central environment is like. Therefore, when the gamma-ray telescope EGRET detected an excess of gamma-rays over the expected background coming from within 0.2° of the center, several candidates for the emission were suggested on the basis of their characteristics known from the low-frequency observations. Two promising sources, the massive black hole candidate Sgr A* and the extended shell structure Sgr A East, are considered here. We first investigate in detail the hadronic processes contributing to the gamma-ray emission, and then compare predicted spectra to the EGRET data. We conclude that Sgr A* cannot be the source but that Sgr A East is very promising, and suggest further observational tests. Understanding the high energy processes in our Galactic center is crucial for our modeling of the same processes throughout our Galaxy as well as in distant galaxies. Because we have so much more information about the Galactic center physical environment, we have the opportunity to test our theories in a familiar surrounding before attempting to apply our ideas to places we can never hope to resolve so well. The Galactic center may hold the key to our understanding of the high energy interactions in blazars, supernova remnants and by cosmic rays.

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-62).
In this thesis, I develop an exclusive cone jet algorithm based on the principles of jet substructure and demonstrate its use for physics analyses at the Large Hadron Collider. Based on the event shape N-jettiness, this algorithm, called "XCone," partitions the event into a fixed number of conical jets of size RO in the rapidity-azimuth plane. This algorithm is designed to locate substructure independent of momentum, allowing accurate resolution of jets at both low and high energy scales. I present three potential analyses using XCone to search for heavy resonances, Higgs bosons, and top quarks at various momenta and show that it reconstructs these particles with efficiencies between 60% and 80% without any additional substructure techniques, and maintains this efficiency over a wide kinematic range. This algorithm provides many key advantages over traditional jet algorithms that make it appealing for use at the LHC and other high energy particle colliders.
by Thomas Frederick Wilkason, Jr.
S.B.

The main goal of this dissertation was to study two- and three-nucleon Short Range Correlations (SRCs) in high energy three-body breakup of 3He nucleus in 3He(e, e'NN)N reaction. SRCs are characterized by quantum fluctuations in nuclei during which constituent nucleons partially overlap with each other. A theoretical framework is developed within the Generalized Eikonal Approximation (GEA) which upgrades existing medium-energy methods that are inapplicable for high momentum and energy transfer reactions. High momentum and energy transfer is required to provide sufficient resolution for probing SRCs. GEA is a covariant theory which is formulated through the effective Feynman diagrammatic rules. It allows self-consistent calculation of single and double re-scatterings amplitudes which are present in three-body breakup processes. The calculations were carried out in detail and the analytical result for the differential cross section of 3He(e, e'NN)Nreaction was derived in a form applicable for programming and numerical calculations. The corresponding computer code has been developed and the results of computation were compared to the published experimental data, showing satisfactory agreement for a wide range of values of missing momenta. In addition to the high energy approximation this study exploited the exclusive nature of the process under investigation to gain more information about the SRCs. The description of the exclusive 3He(e, e'NN)N reaction has been done using the formalism of the nuclear decay function, which is a practically unexplored quantity and is related to the conventional spectral function through the integration of the phase space of the recoil nucleons. Detailed investigation showed that the decay function clearly exhibits the main features of two- and three-nucleon correlations. Four highly practical types of SRCs in 3He nucleus were discussed in great detail for different orders of the final state re-interactions using the decay function as an unique identifying tool. The overall conclusion in this dissertation suggests that the investigation of the decay function opens up a completely new venue in studies of short range nuclear properties.

Quantum chromodynamics (QCD) is the fundamental theory in elementary particle physics that describes the strong interaction in terms of exchanges of force-carrying, colour-charged particles known as gluons. Although well-established through experimental verifications, there are fundamental unsolved problems in the theory.

In this thesis, some novel aspects of strong interaction dynamics are studied in the context of colour singlet exchange processes — interactions where complex systems of gluons with no net colour charge are exchanged. Both perturbative and non-perturbative QCD methods are used, as well as Monte Carlo computer simulations.

Soft colour interactions in the final state of a high energy collision can lead to effective colour singlet exchange. Non-perturbative models for such interactions are shown to give a good description of diffractive production of W, Z, bb, J/ψ and jets in pp collisions at the Tevatron. Predictions are given for diffractive Higgs boson and prompt photon production at hadron colliders.

Rapidity gaps between jets is a new phenomenon which is studied with an improved perturbative calculation of hard colour singlet exchange using the BFKL equation, taking into account previously neglected contributions and non-leading logarithmic corrections. Including also underlying soft rescattering effects, the complete model reproduces well data from the Tevatron.

Diffractive vector meson production through hard colour singlet exchange in γp collisions is studied in the framework of the conformal invariant non-forward solution of the BFKL equation. Expressions for helicity-dependent amplitudes are derived, and the results show good agreement with data on J/ψ and ρ production from the ep collider HERA.

These studies lead to a deeper knowledge of complex gluon dynamics, and therefore advance our understanding of QCD.

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The Standard Model of particle physics is examined in the context of high energy proton-antiproton collider experiments. The large energies available offer the possibility of producing new particles which may then be observed via their decay. Heavy quark production is examined through the production of unlike-sign lepton pairs. Methods for isolating several dilepton production mechanisms are given, including an eu signal for the top quark. Moreover, ψ production is shown to serve as a particularly clean tag for the production of particles containing b quarks. The possibility of observing a fourth generation heavy lepton via W decay is investigated. The hadronic decay mode leads to a promising signature of large missing accompanied by two hadronic jets and has a very healthy event rate. The monojet events found by the UA1 experiment are reviewed. Various extensions of the Standard Model are examined as possible explanations of these events. The first interpretation involves the production of SUSY particles. These are found to be compatible with the data if two squarks exist with mass 0(30GeV) and the gluino has mass > 0(60GeV). Secondly, interpretations based on four point effective interactions of the form qqZg are investigated, and are shown to be unable to account for the observed monojet rate. Finally, the production and decay of new heavy states (for example excited quarks) could account for the monojet data, but are found to predict large numbers of W + jet and γ + jet events which have not been seen.

Many Beyond-the-Standard-Model theories predict the existence of one or more additional neutral gauge bosons, or Z' bosons, with masses at the TeV scale or higher. A search for resonances of Z' bosons decaying to τ⁺ τ^- pairs in [special characters omitted]s = 8 TeV pp collisions from the LHC is presented. The data was collected by the ATLAS detector and corresponds to an integrated luminosity of 19.5-20.3 fb^-1. The search is performed in ditau decay channels in which at least one tau decays hadronically. In each channel, the numbers of ditau events in high-mass regions of data are counted and compared to the expected numbers from Standard Model backgrounds and Z' signals. No statistically significant excess above the Standard Model expectation is observed in any channel. Bayesian 95% credibility upper limits are placed on the Z' production cross section times Z' → ττ branching ratio as functions of the Z' resonance mass for each channel and for a combination of the channels. Sequential Standard Model Z' bosons with masses below 2.02 TeV are excluded at 95% credibility. The impacts on the cross section limits from varying the Z_ssM decay width and couplings to fermions are evaluated. Limits are also placed on the cross section times branching ratio of Non-Universal G(221) Z' bosons with enhanced couplings to third-generation fermions. These are evaluated as functions of the Z'_NU mass and another free parameter. Z'_Nu bosons with masses below 1.3-2.1 TeV are excluded at 95% credibility.

T2K is a long baseline neutrino oscillation experiment located in Japan. It was built mainly to detect muon neutrino to electron neutrino oscillation and to measure the mixing angle &thetas;₁₃ of the PMNS matrix, along with the precision measurement of &thetas;₂₃ and mass differences. A ν_μ beam is produced at the Japan Proton Accelerator Research Complex (J-PARC) in Tokai and travels to the far detector in Kamioka, Japan. There is an ensemble of detectors at 280 m downstream of the target that form the near detector. Super-Kamiokande, a water Cherenkov detector, located 295 km away from the target serves as the far detector.

The two main backgrounds for electron neutrino appearance at the Super-Kamiokande are the inherent electron neutrino component of the beam and the \pizero{} particle produced via neutral current channel (NC1π⁰) that mimics the electron neutrino interaction signature. To effectively constrain the NC1π⁰ interaction rate on water, the Pi0 Detector (P0D) was built as one of the near detectors. This detector can be filled and drained with water periodically to enable extraction of neutrino interactions on water.

This analysis measures the NC1π⁰ interaction rate on water in the P0D. It uses neutrino beam data of 3.53 × 10²⁰ protons-on-target (POT) for the water-in configuration of the P0D and 6.70 × 10²⁰ POT for the water-out configuration. A set of selections are implemented to obtain a sample enriched in signal events.

The π⁰ invariant mass distribution is compared between data and Monte Carlo. Parameter estimation using Markov Chain Monte Carlo sampling method is performed to measure the signal events in data.

The data fit results in 130 ± 20 events on water including both statistical and systematic uncertainties for an expected value of 167 events predicted by the NEUT Monte Carlo. The ratio between nominal Monte Carlo and the best fit value is 0.78 ± 0.12.

This dissertation shows the first evidence of the process e ⁺e⁻ → γη _c(1S) using data collected by the BESIII experiment operating at BEPCII. This process can be used as a probe to study the nature of recently discovered charmonium-like Y states between 4.0 and 4.6 GeV, including the Y(4260) and Y(4360). Data collected at six center-of-mass energies are analyzed, namely: 4.01, 4.23, 4.26, 4.36, 4.42, and 4.60 GeV, corresponding to a total integrated luminosity of 4.6 fb⁻¹. We measure the Born cross section, σ _E(e⁺e ⁻ → γη_c(1 S)), at each energy using a combination of twelve η _c(1S) decay channels. Because the significance of the signal is marginal at each energy (≤ 3.0σ), we also combine all six energies under various assumptions for the energy-dependence of the cross section. If a Y(4260) is assumed, we measure σ4 _.26(e⁺e⁻ → γη_c(1S)) = 2.11 ± 0.49 (stat.) ± 0.33 (syst.) pb with a significance of 4.2σ. With our current statistics we are unable to distinguish the Y(4260) process from others.

Ionic currents were used to probe amorphous MnO

2

, which is a battery cathode material in lithium ion batteries, that was template electrodeposited in polycarbonate cylindrical nanopores. The porous MnO

2

occupies the volume extending approximately 1 μm into the pore from one end and nanovoid channels, in the MnO

2

, allow for electrolyte solution to pass through from one end to the other.

Presented in this thesis are the results of ionic current studies used to probe ion transport through amorphous MnO

2

, in different oxidation states, with 100 mM LiClO₄ electrolyte in propylene carbonate (PC) solvent. Current-voltage curves, from ionic current-measurements, were unable to resolve excess surface charge in the electrodeposited MnO

2

. A comparison of current-voltage curves from when the MnO

2

was cycled between lithium inserted and deinserted oxidation states showed a trend of increasing resistance over a series of three lithium insertion and deinsertion cycles.

Neutrino oscillation is a phenomenon in which neutrinos produced from charged current weak interactions can change flavor as they propagate. The mixing between the three flavor eigenstates and mass eigenstates can be measured through neutrino oscillations as the oscillation probabilities depend on the mixing angles and neutrino mass squared differences.

T2K is a long baseline neutrino experiment, in which a nearly pure muon neutrino or muon antineutrino beam is produced at J-PARC on the east coast of Japan and travels 295 km through the Earth’s crust towards the far detector, Super-Kamiokande (Super-K), a 50 kiloton water Cherenkov detector, in the west of Japan. The neutrino fluxes in the absence of oscillation are measured by the near detectors 280 meters away from the target, and again with oscillation effects at Super-K. Aside from the beam neutrino from J-PARC, Super-K also measures neutrino oscillations independently through the neutrinos produced in the Earth's atmosphere.

This thesis presents the first analysis in which both the T2K beam neutrino data and the sub-GeV atmospheric neutrino data at Super-K are used in a unified framework to measure neutrino oscillation parameters. The beam neutrino samples are selected for optimal sensitivity to sin²&thetas;₂₃ and δ_CP. A Bayesian analysis using a Markov Chain Monte Carlo method is performed. Using T2K Runs 1–8 data which amounts to 14.7 × 10₂₀ protons on target (POT) in neutrino-mode and 7.6 × 10₂₀ POT in antineutrino-mode, and 2520 days of Super-K data, the oscillation parameters are measured to be sin²&thetas; ₂₃ = 0.528^+0.032_–0.028, |Δ m²₃₂| = 2.46^+0.084 _–0.060(10^–3eV²), sin ²&thetas;₁₃ = 0.0270^+0.0065_–0.0047 ; and the 90% credible interval of δ_CP is [–π, –0.18]&[2.33, π]. When the data is also combined with the constraint on sin² 2&thetas;₁₃ = 0.0857 ± 0.046 from reactor neutrino experiments, the oscillation parameters are measured to be sin²&thetas;₂₃ = 0.543^+0.026 _–0.023, |Δm² 32| = 2.49 ^+0.042_–0.090(10^–3eV² ), sin²&thetas;₁₃ = 0.0223^+0.0012 _–0.0013; the 90% credible interval of δ _CP is [–π, –0.628], and the CP-conserving value δ _CP = 0 is excluded at 2σ.

Silicon tracking detectors are frequently used in particle collider experiments, as they can provide excellent spatial precision with little material in order to cause minimal track disruption. Due to a progressive increase in collider luminosities, a common trend in these experiments is the need for higher levels of radiation damage resistance. One proposed class of designs for pixel trackers in high luminosity colliders is the Silicon 3D trench detector. The same design can be scaled up for photon science applications.

The work discussed in this dissertation was performed as part of a collaboration between BNL, NYU, CNM and SUNY Stony Brook. The central aim of the work presented here was to evaluate the manufactured 3D trench detector prototypes and study their behavior in detail by performing a series of experimental measurements and TCAD simulations.

An experiment to measure the detector response to an Americium radioactive source was designed and used to study the noise level and charge collection efficiency of detector prototypes. An experimental system which measured the detector response to an infrared laser with computer controlled precision positioning was developed. This system was used to obtain laser pulse response maps of detectors, which in turn were utilized to investigate the dependence of charge collection efficiency of detectors on position, collection time and bias voltage. The same mapping technique was also used to study the change in irradiated detector response.

Detector response was simulated using the Silvaco TCAD Suite. These simulations were used to study depletion in large photon detectors and charge collection in response to laser hits. Approximate simulations of radiation damage were also performed to investigate the behavior of irradiated detectors. Leakage current and capacitance simulations before and after irradiation were also performed and compared to the experimental measurements. While significant variations in detector response between different prototypes were observed during the experiments, simulation results are still capable of explaining the general properties of the detectors. The combination of the simulation and the experimental results provides an understanding of the signal generation process in these detectors.

One observed problem is the large bias currents due to manufacturing surface defects. A double-sided version of the trench detector is proposed to mitigate this problem. Electric fields, depletion region shape and formation, bias voltage and transient current response of these detectors are simulated and compared with those of the standard trench detectors. Computer simulations show that the double-sided detectors also have some performance advantages over the original designs including larger more uniform spatial charge collection efficiency and higher radiation damage resistance. These simulation results and the general insensitivity of the proposed detectors to surface defects make the double-sided detectors worthy of further study.

A search for Higgs boson pair production in the four b-jet final state is carried out with up to 36.1/fb of LHC proton--proton collision data collected at √s = 13 TeV with the ATLAS detector in 2015 and 2016. Three benchmark signals are studied: a spin-2 graviton decaying into a Higgs boson pair, a scalar resonance decaying into a Higgs boson pair, and Standard Model non-resonant Higgs boson pair production. This thesis presents a search in events with four individually resolved b-tagged jets. Higgs bosons produced with large momenta are reconstructed as single large radius jets with substructure. The analysis of this topology is presented in CERN-THESIS-2018-118. The two analyses are statistically combined and upper limits on the production cross section of Higgs boson pairs times branching ratio to four b-quarks are set in each model. The combined result searches for resonance masses in the range 260–3000 GeV. No significant excess is observed; the largest deviation of data over prediction is found at a mass of 280 GeV, corresponding to 2.3 standard deviations globally. The observed 95% confidence level upper limit on the non-resonant production is 13 times the Standard Model prediction.

The search for phenomena Beyond the Standard Model (BSM) is the primary motivation for the experiments at the Large Hadron Collider (LHC). This dissertation assesses the experimental status of supersymmetric theories based on analyses of data collected by the ATLAS experiment during the first and second run of the LHC. Both R-parity preserving theories defined within the framework of the Minimally Supersymmetric Standard Model (MSSM) as well as R-parity violating models are studied. Further, a framework for systematic reinterpretation, RECAST, is presented which enables a streamlined, community-wide, approach to the search for BSM physics through the preservation of data analyses as parametrized computational workflows. A language and execution engine for such workflows of heterogeneous workloads on distributed computing systems is presented. Additionally, a new implementation of the HistFactory class of binned likelihoods based on auto-differentiable computational graphs is developed for accelerated and distributed inference computation. Finally, to enable efficient reinterpretation, a method of estimating excursion sets of one or more resource-intensive, multivariate, black-box functions, such as p-value functions, through an information-based Bayesian Optimization procedure is introduced.

The LHCb experiment probes the differences between matter and anti-matter by examining particle collisions. Like any modern high energy physics experiment, LHCbrelies on a complex hardware and software infrastructure to collect and analyze the data generated from particle collisions. To filter out unimportant data before writing it to permanent storage, particle collision events have to be processed in real-time which requires a lot of computing power. This thesis focuses on performance optimizations of several parts of the real-timedata processing software: i) one of the particle path reconstruction steps; ii) theparticle path refining step; iii) the data structures used by the real-time reconstructionalgorithms. The thesis investigates and employs techniques such as vectorization, cache-friendly memory structures, microarchitecture analysis, and memory allocation optimizations. The resulting performance-optimized code uses today's many-core, data-parallel,superscalar processors to their full potential in order to meet the performance demands of the experiment. The thesis results show that the reconstruction step got3 times faster, the refinement step got 2 times faster and the changes to the datamodel allowed vectorization of most reconstruction algorithms.

X-ray absorption spectroscopy (XAS) is a powerful technique to determine the structure and function of molecules. It provides element-specific information on geometry, chemical bonding, oxidation state, and spin state, and its applications range from biology to material science. For dilute samples, XAS is measured by partial fluorescence yield (PFY), where the intensity of a weak fluorescence line is recorded as a measure of absorption as the energy of the incident x-ray beam is scanned across an absorption edge of the element of interest. PFY increases the sensitivity for XAS if an x-ray detector is used that can efficiently separate the small fluorescence signal of interest from the x-ray background due to other elements in the sample.

This dissertation describes the development of a high-resolution x-ray detector based on arrays of superconducting tunnel junctions (STJs). It is cooled to its operating temperature below 0.3 K with a liquid-cryogen-free adiabatic demagnetization refrigerator cryostat, and offers more than an order of magnitude improvement in energy resolution over conventional Ge- or Si-based solid state detectors. For operation in XAS experiments at a synchrotron, the STJ detector array is held at the end of a cold finger that can be inserted into an ultra-high vacuum endstation. This dissertation describes the design and performance of the STJ x-ray spectrometer, and demonstrates its use in PFY-XAS experiments in metallo-organic compounds at the Advanced Light Source synchrotron.

This thesis describes the construction of a hybrid OPCPA and Nd:Glass based laser system to provide advanced diagnostic capabilities for the MAGPIE pulsed power facility at Imperial College London. The laser system (named Cerberus) is designed to provide one short pulse 500 fs beam for proton probing and two long pulse beams, one for x-ray backlighting and one for Thomson scattering. The aim of this project is to accurately determine plasma parameters in a range of demanding experimental environments. The thesis is split into two sections; the first section provides details about the design and implementation of the laser system while the latter chapters present experimental data obtained on the MAGPIE facilty. The front end for the laser system is based on optically synchronised Optical Parametric Chirped Puled Amplification (OPCPA) which is supplemented by large aperture flashlamp pumped Nd:Glass power amplifiers in the latter stages to increase the energy to the Joule level. The use of optical parametric amplifiers (OPAs) in the pre-amplifier stages reduces gain narrowing, B-integral and improves contrast. Simulations of the dispersive optics for the Chirped Pulse Amplification (CPA) system are described in detail. Spatially resolved Thomson scattering was used to measure temperature and velocity of ablation streams in aluminium and tungsten cylindrical wire arrays. The measurements show a peak ow velocity of 120 km/s and agree well with 3D MHD simulations for the case of aluminium. There is discrepancy with the tungsten data caused by the difficulty in handling of collisionality calculations. Novel data showing the self-emission of ions from tungsten radial wire arrays is presented as a key step towards laser driven proton probing of MAGPIE. It is observed that the bulk of the emission corresponds to low energy protons with energies of ~ 100 keV. Protons with energy > 600 keV were observed to emanate from the collapsing magnetic jet using a coded aperture camera. These results offer interesting new prospects in diagnosing wire arrays.

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 53-54).
My work in this thesis is a contribution toward the IsoDAR experiment, which aims to test the sterile neutrino hypothesis. In the IsoDAR experiment, neutrinos are generated by a 60 MeV proton beam impinging on a 9Be target and diffusing through 7 Li. This results in 'Li which beta decays, thereby producing an electron-antineutrino beam. To overcome space charge limitations, H+ is accelerated instead of protons. Acceleration is accomplished by a cyclotron, and the beam injected into the cyclotron needs to have a low emittance (a figure of merit for the beam quality). This is where the need for a way to measure our beam's emittance arises. This thesis covers the process of designing, fabricating, assembling, and commissioning an emittance scanner. The main challenges I faced were the high-intensity of the beam and a need for high precision. I designed an emittance scanner using CAD software. Its parts were then machined in MIT's Central Machine Shop and subsequently built and installed into vacuum. As of now, preliminary commissioning of the scanners has begun with a few initial scans already performed. The scan
by Jesus Corona.
S.B.

This dissertation examines applications of methods of high-energy theory to other physical systems: unconventional superconductors on the one hand, and cosmology on the other. Extra-dimensional models of superconductors, motivated by gauge/gravity duality in string theory, have proven remarkably successful in reproducing qualitative, and sometimes quantitative, aspects of unconventional superconductors. We analyze the universality of some of these predictions, and discover a universal relation between certain superconducting observables. The second part of this dissertation is about cosmic inflation. The evolution of the universe is sensitive to the fundamental particles and their interactions. We investigate models of cosmic inflation which involve the dynamics of one or more axion fields, and we explain how such models might be related to the flavor structure of the standard model.

Includes bibliographical references.
Obtained via the maximisation of a modified entropy, the Tsallis distribution has been used to fit the transverse momentum distributions of identified particles from several high energy experiments. We propose a form of the distribution described in Cleymans and Worku, 2012, and show it to be thermodynamically consistent. Transverse momenta distributions and fits from ALICE, ATLAS, and CMS using both Tsallis and Boltzmann distributions are presented.

Els experiments d’alta energia de física (HEP) a col·lisions de partícules demostren la nostra comprensió de l’estructura i la dinàmica de la matèria. Per avançar en el camp, els sistemes d’acceleradors s’actualitzen periòdicament a energies i lluminositats més elevades. Els experiments han de mantenir-se al punt millorant la seva instrumentació de detecció. Els detectors de píxels de silici tenen un paper crític en els experiments HEP. Gràcies a la seva excel·lent resolució de posició, compacitat, velocitat i duresa de la radiació, permeten la reconstrucció de la pista de partícules en entorns d’alta radiació com els col·lisionadors de hadrons. Al seu torn, el seu rendiment permet una excel·lent resolució de paràmetres d’impacte de pista, un ingredient clau per a la identificació de vèrtexs secundaris i l’etiquetatge b del jet. Actualment, el detector estàndard de píxels consisteix en un sensor segmentat, en el qual cada píxel està connectat a un canal de lectura d’un circuit integrat d’aplicacions específiques per a aplicacions (ASIC) mitjançant una tècnica complicada i cara, anomenada enllaç de cop. Un mètode alternatiu per als dispositius de píxels híbrids són els detectors monolítics, que combinen la detecció de partícules i les tasques de processament de senyal al mateix substrat. Aquests tipus de detectors desenvolupats en el procés CMOS han estat utilitzats en el passat, però només recentment es basen en dispositius de radiació durs. sobre aquesta tecnologia s’han proposat. En aquesta tesi s’investiga un primer prototip a mida completa d’un detector monolític desenvolupat en la tecnologia CMOS d’Alta Voltatge (HV-CMOS) com a dispositiu de píxel per a les capes exteriors del futur rastrejador ATLAS actualitzat, que es troba al Gran Col·lisionador d’Hadrons ( LHC) al CERN. A més de l’aplicació d’aquesta tecnologia en experiments HEP, la detecció de fotons de raigs X suaus també s’investiga en una matriu en un dels detectors de píxels HV-CMOS. Per últim, s’explora l’ús de dispositius CMOS per a la detecció de fotons de gairebé infraroig (NIR) amb fotodiode d’Avalanche (APD).
Los experimentos de física de alta energía (HEP) en colisionadores de partículas sondean nuestra comprensión de la estructura y la dinámica de la materia. Para avanzar en el campo, los sistemas de aceleración se actualizan periódicamente a mayores energías y luminosidades. Los experimentos tienen que mantenerse al día, mejorando la instrumentación de su detector. Los detectores de píxeles de silicio desempeñan un papel fundamental en los experimentos con HEP. Gracias a su excelente resolución de posición, compacidad, velocidad y dureza de radiación, permiten la reconstrucción de pistas de partículas en entornos de alta radiación como colisionadores de hadrones. A su vez, su rendimiento permite una excelente resolución de parámetros de impacto en la pista, un ingrediente clave para la identificación secundaria de vértices y el etiquetado de chorro b. Actualmente, el detector de píxeles estándar consta de un sensor segmentado, en el que cada píxel está conectado a un canal de lectura de un circuito integrado de aplicación específica (ASIC) a través de una técnica complicada y costosa llamada unión por golpes. Un enfoque alternativo a los dispositivos de píxeles híbridos son los detectores monolíticos, que combinan la detección de partículas y las tareas de procesamiento de señales en el mismo sustrato. Estos tipos de detectores desarrollados en el proceso CMOS se han utilizado en el pasado, pero solo relativamente recientemente basados ​​en dispositivos de radiación dura sobre esta tecnología se han propuesto. En esta tesis, se investiga un primer prototipo de tamaño completo de un detector monolítico desarrollado en la tecnología CMOS de alto voltaje (HV-CMOS) como un dispositivo de píxeles para las capas externas del rastreador ATLAS de actualización futura, que se encuentra en el Gran Colisionador de Hadrones ( LHC) en el CERN. Además de la aplicación de esta tecnología en experimentos HEP, la detección de fotones de rayos X blandos también se investiga en una matriz en uno de los detectores de píxeles HV-CMOS. Por último, se explora el uso de dispositivos CMOS para la detección de fotones de infrarrojo cercano (NIR) con Avalanche Photodiode (APD).
High Energy Physics (HEP) experiments at particle colliders probe our understanding of the structure and dynamics of matter. In order to advance the field, the accelerator systems are periodically upgraded to higher energies and luminosities. Experiments have to keep up, by improving their detector instrumentation. Silicon pixel detectors play a critical role in HEP experiments. Thanks to their excellent position resolution, compactness, speed and radiation hardness, they enable particle track reconstruction in high radiation environments like hadron colliders. In turn, their performance allows excellent track impact parameter resolution, a key ingredient for secondary vertex identification and jet b-tagging. Currently the standard pixel detector consists of a segmented sensor, in which each pixel is connected to a readout channel of an Application-Specific Integrated Circuit (ASIC) through a complicated, and expensive, technique called bump bonding. An alternative approach to hybrid pixel devices are monolithic detectors, which combine the particle sensing and the signal processing tasks in the same substrate.These kinds of detectors developed in the CMOS process have been used in the past, but only relatively recently radiation hard devices based on this technology have been proposed. In this thesis a first full size prototype of a monolithic detector developed in the High Voltage CMOS (HV-CMOS) technology is investigated as a pixel device for the outer layers of the future upgrade ATLAS tracker, which is located in the Large Hadron Collider (LHC) at CERN. Besides the application of this technology in HEP experiments, the detection of soft X-ray photons is also investigated in one matrix in one of the HV-CMOS pixel detectors. Lastly, the usage of CMOS devices for the detection of Near-Infrared (NIR) photons with Avalanche Photodiode (APD) is explored.

A desired trend within high energy physics is to increase particle accelerator luminosities,leading to production of more collision data and higher probabilities of finding interestingphysics results. A central data analysis technique used to determine whether results areinteresting or not is the maximum likelihood method, and the corresponding evaluation ofthe negative log-likelihood, which can be computationally expensive. As the amount of datagrows, it is important to take benefit from the parallelism in modern computers. This, inessence, means to exploit vector registers and all available cores on CPUs, as well as utilizingco-processors as GPUs.This thesis describes the work done to optimize and parallelize a prototype of a centraldata analysis tool within the high energy physics community. The work consists of optimiza-tions for multicore processors, GPUs, as well as a mechanism to balance the load betweenboth CPUs and GPUs with the aim to fully exploit the power of modern commodity comput-ers. We explore the OpenCL standard thoroughly and we give an overview of its limitationswhen used in a large real-world software package. We reach a single-core speedup of ∼ 7.8xcompared to the original implementation of the toolkit for the physical model we use through-out this thesis. On top of that follows an increase of ∼ 3.6x with 4 threads on a commodityIntel processor, as well as almost perfect scalability on NUMA systems when thread affinityis applied. GPUs give varying speedups depending on the complexity of the physics modelused. With our model, price-comparable GPUs give a speedup of ∼ 2.5x compared to amodern Intel CPU utilizing 8 SMT threads.The balancing mechanism is based on real timings of each device and works optimally forlarge workloads when the API calls to the OpenCL implementation impose a small overheadand when computation timings are accurate.

This thesis contains studies of phenomenological aspects of new physics at hadron colliders, such as the Large Hadron Collider (LHC). After a general introduction in chapter 1, in chapter 2 we outline the main features of the Standard Model (SM) of particle physics and the theoretical motivations for going beyond it. We subsequently provide brief descriptions of a few popular models that aim to solve the issues that arise within the SM. In chapter 3 we describe the general Monte Carlo method for evaluating multidimensional integrals and show how it can be used to construct a class of computational tools called Monte Carlo event generators. We describe the main generic features of event generators and how these are implemented in the HERWIG++ event generator. By applying resummation techniques, we provide, in chapter 4, analytical calculations of two types of hadron collider observables. The first, global inclusive variables, are observables that make use of all measured particle momenta and can provide useful information on the scale of new physics. The second observable is the transverse energy of the QCD initial state radiation (ET ), associated with the either Drell-Yan gauge boson production or Higgs boson production. In both cases we provide comparisons to results obtained from Monte Carlo event generators. In chapter 5 we examine two well-motivated models for new physics: one of new heavy charged vector bosons (W prime), similar to the SM W gauge bosons, and a model motivated by strong dynamics electroweak symmetry breaking that contains new resonances, leptoquarks, that couple primarily to quarks and leptons of the third generation. In the prior model, we improve the current treatment of the W' by considering interference effects with the SM W and construct an event generator accurate to next-to-leading order which we use to conduct a phenomenological analysis. For the leptoquark model, starting from an effective Lagrangian for production and decay, we provide an implementation in the HERWIG++ event generator and use it to form a strategy for mass reconstruction. The thesis ends with some conclusions and suggestions for extensions of the work presented. Further details and useful formulæ are given in the appendices.

A review of the development of parallel computing is presented, followed by a summary of currently recognised types of parallel computer and a brief summary of some applications of parallel computing in the field of high energy physics. The computing requirement at the data acquisition stage of a particular set of high energy physics experiments is detailed, with reference to the computing system currently in use. The requirement for a parallel processor to process the data from these experiments is established and a possible computing structure put forward. The topology proposed consists of a set of rings of processors stacked to give a cylindrical arrangement, an analytical approach is used to verify the suitability and extensibility of the suggested scheme. Using simulation results the behaviour of rings and cylinders of processors using different algorithms for the movement of data within the system and different patterns of data input is presented and discussed. Practical hardware and software details for processing equipment capable of supporting such a structure as presented here is given, various algorithms for use with this equipment, e. g. program distribution, are developed and the software for the implementation of the cylindrical structure is presented. Appendices of constructional information and all program listings are included.

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, February, 2020
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-89).
With continuing developments in experimental high energy physics, more and more data is being produced for analysis. As the size of data sets grows, the runtime and computational requirements of traditional inference procedures can become intractable. The problem of scalable inference appears in many fields, and thus it is an area of continuous development in computer science. With the proliferation of improved methods for data summarization and inference, an increasingly large onus is placed on individual researchers to determine the most appropriate methods for their specific problems. This work outlines the fundamentals of inference in high energy physics to establish a common foundation for readers in physics and computer scientist. It continues on to present a new set of tools that is designed to be used by researchers to evaluate summarization and inference methods for use on customized problems. The work presents sample evaluation results that can be produced by this tool. Finally, the work outlines how the tool can be used by researchers and highlights potential directions of interest in the search for more efficient inference techniques to be used in the field of high energy physics.
by Hannah R. Diehl.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Le ricerche e le scoperte fatte nell'ambito della fisica sono fortemente dipendenti dall'efficienza e dall'affidabilità degli esperimenti ad alta energia. L'obiettivo principale è lo studio delle particelle che costituiscono la materia in termini di cariche elementari, loro interazioni e prodotti secondari che ne possono derivare. L'LHC (Large Hadron Collider) lavora al CERN ogni giorno con l’obiettivo di scoprire nuovi dettagli su particelle cariche come neutroni e Bosoni di Higgs. Queste sono generate e accelerate all’interno dell’LHC e vengono rilevate da opportuni detector organizzati in una struttura a shell. In questo modo, è possibile avere una caratterizzazione in termini di momento, carica elettrica, energia, tempo di volo e distanza associati alla particella rilevata. La progettazione dei rilevatori è importante come anche quella dell’elettronica vicina. Un grande esperimento richiede un duro lavoro di scienziati e ingegneri. Negli ultimi anni, l’elettronica è sempre più efficiente e compatta grazie alla sostituzione dei componenti discreti con circuiti integrati CMOS. La progettazione deve essere però fatta considerando sia le reti di interfacciamento con i sensori sia l’ambiente radiattivo circostante. Le radiazioni, infatti, possono modificare parzialmente o totalmente le performance e la scelta della tecnologia scalata può però essere di grande aiuto. In questo scenario, sono stati progettati, integrati e misurati 3 circuiti di lettura per esperimenti di fisica delle alte energie. 2 prototipi sono stati realizzati in tecnologia 130nm per l'esperimento ATLAS in collaborazione dell’Istituto Max-Plank di Monaco. Questi prototipi sono pensati per rilevare cariche fino a 100fC e convertirle in un segnale di tensione di ampiezza variabile che sarà processato in digitale per avere informazioni sull’istante di arrivo della carica e sulla sua intensità. A tal fine, gli integrati hanno uno stadio di discriminazione ed un Wilkinson ADC in grado di convertire in un tempo il segnale in tensione ricevuto. Il secondo prototipo è molto simile al primo. Esso è stato migliorato principalmente per poter essere più immune ai disturbi provenienti da masse e alimentazioni. Il terzo circuito presentato in questa tesi è un sistema di lettura progettato per Pixel detectors in tecnologia CMOS 28nm. Il canale integrato include un preamplificatore di carica con un comparatore in cascata. L'utilizzo della tecnologia 28nm con la sua ridotta alimentazione comporta una serie di difficoltà nella progettazione ma anche una maggiore resistenza alle radiazioni, consumi ridotti e una minor area occupata. I circuiti sono stati progettati per due differenti scenari in termini di capacità parassita del rilevatore, cariche di ingresso rilevabili, alimentazioni, soglie, consumi di potenza e rumore. In tutti i casi, però, i sistemi sono in grado di fornire le informazioni sulla carica rilevata in tempi relativamente rapidi (entro 25ns). Questo aspetto è molto importante e permette di evitare errori. Collisioni successive potrebbe causare segnali spuri e si potrebbe rilevare come unico evento due eventi distinti e consecutivi. Questo lavoro è organizzato come segue. La Parte I include una breve introduzione sull'intera attività svolta nei tre anni di attività di ricerca. La Parte II è dedicata alla descrizione semplificata del campo di applicazione ed ai target previsti per i prossimi esperimenti di fisica. In particolare, sono forniti alcuni dettagli su come l'elettronica può essere influenzata dalla presenza delle radiazioni. Le parti III e IV rappresentano il core della tesi perché mirano all'analisi dettagliata dei circuiti progettati e descritti precedentemente in maniera generica. L'analisi prevede una caratterizzazione completa degli integrati con simulazioni e misure. Infine, prima di concludere, la Parte V è dedicata alla pubblicazioni correlate all'attività di ricerca.
Physic researches and discoveries depend heavily from efficient and reliability of the High-Energy Physics (HEP) experiments. The main goal is to study the fundamental constituents of the matter in terms of elementary charge particles, their interactions and their secondary products. The Large Hadron Collider (LHC) at the CERN works every day to discover details on new charged particles as neutrinos and Higgs Bosons. Charges are generated and accelerated from beam collisions inside the LHC. Different detectors are organized in shell structures and are designed to detect few particles topology. Typically, the parameters useful to identify a charged particle are momentum, electrical charge, energy, time of flight and distance. Detectors design is important but it is enhanced from proper electronic readout systems. In the last years, electronics parts are more and more efficient and compact. CMOS integrated solution are preferred to discrete one allowing major reliability, cost reduction and performance improvement. The design is not trivial but not impossible. Some characteristics depend on the electronic designer and his capability to manage the external parasitic effects, as the parasitic capacitance of the connected detector. Unfortunately, phenomena as radiation effects on electronics must be taken in account but they are not completely eliminated. CMOS technology influences strongly the integrated circuit performance and radiation hardness. In this scenario, 3 readout frontend circuits for HEP experiments have been designed, integrated and measured. 2 of them represent 2 different prototypes realized in IBM 130nm technology for ATLAS experiment at CERN laboratory with Max-Plank Institute for Physics collaboration. They include an analog chain in cascade with a digital one. Input charges (up to 100fC) are detected and converted into voltage signals. Their amplitude are proportional to the input and are sent to the following digital part. The digital part provides information about arrival time and amount of the input charge. When the discriminator switches, an event is detected and the Wilkinson ADC starts the voltage-to-time conversion. The full chips have a JTAG section to manage all programmable parameters (i.e. thresholds, hysteresis, deadtime, etc.) The second prototype is designed improving the previous version in terms of supply rejection noise, deadtime range and hysteresis management. The third circuit presented in this thesis is the first readout frontend for Pixel detectors in 28nm technology. The channel includes a charge sensitive preamplifier with an inverter switched based comparator. Reduced supply voltage and 28nm technology imply some difficult in the design with a major tolerance to the radiations, a lower area occupancy and a lower power consumption. The circuits are been designed for 2 different scenarios in terms of detector parasitic capacitance, detectable input charges, supply voltage, threshold voltage, power consumption and noise. In overall cases, the integrated systems provide information about amount of detected input charge and arrival time within 25ns. This aspect is very important and allows avoiding mistakes. Successive collisions lead to spurious signals presence and a single detection could have information about two different events. Maintaining the processing time within 25ns, consecutive collisions are detected as different events. This work is organized as follows. Part I includes a brief summary of the entire work in order to fix the goals of my activities. Then, the Part II is dedicated on a simplified description of the application field and the next target of the future experiments. In particular, some details on the effects induced by the radiation to integrated electronic component are provided. Part III and Part IV represent the core, including 3 readout frontend circuits design and measurements. Finally, there are correlated publications and conclusions.

A Zenith-386 workstation was outfitted with a DICRES-54.8 paralell port board to facilitate I/C between a large Summagrid x-y coordinate digital measurement pad that has a resolution of 10 microns. Film views of high energy particle collisions can be projected onto this pad for measurement. Voice prompts via a Votrax speech synthesis system are sent at critical points during the algorithm from the Z-386 through other ports of the DICRES board. Progress in measurement is fed into the Z-386's serial port from an Interstate voice recognition system at other points of the measurement algorithm. The whole measurement process is managed by an assembler language based modular computer program.
Department of Physics and Astronomy