Diego Casadei

Diego Casadei
Cosylab Switzerland

PhD, Physics

About

416
Publications
983,078
Reads
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29,687
Citations
Additional affiliations
December 2017 - present
University of Johannesburg
Position
  • Research Associate
Description
  • ATLAS experiment at CERN
December 2015 - December 2017
University of Birmingham
Position
  • Fellow
Description
  • ATLAS experiment at CERN
March 2013 - September 2015
University College London
Position
  • Researcher

Publications

Publications (416)
Article
Full-text available
The Spectrometer/Telescope for Imaging X-rays (STIX) is a remote sensing instrument on Solar Orbiter that observes the hard X-ray bremsstrahlung emission of solar flares. This paper describes the STIX Aspect System (SAS), a subunit that measures the pointing of STIX relative to the Sun with a precision of ±4″, which is required to accurately locali...
Article
Aims. The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter is a hard X-ray imaging spectrometer, which covers the energy range from 4 to 150 keV. STIX observes hard X-ray bremsstrahlung emissions from solar flares and therefore provides diagnostics of the hottest (⪆10 MK) flare plasma while quantifying the location, spectrum, and e...
Preprint
The Micro Solar-Flare Apparatus (MiSolFA) is a compact X-ray imaging spectrometer designed for a small 6U micro-satellite. As a relatively inexpensive yet capable Earth-orbiting instrument, MiSolFA is designed to image the high-energy regions of solar flares from a different perspective than that of Solar Orbiter's STIX, operating from a highly ell...
Article
The Micro Solar-Flare Apparatus (MiSolFA) is a compact X-ray imaging spectrometer designed for a small 6U micro-satellite. As a relatively inexpensive yet capable Earth-orbiting instrument, MiSolFA is designed to image the high-energy regions of solar flares from a different perspective than that of Solar Orbiter’s STIX, operating from a highly ell...
Research
Full-text available
I found this polynomial while studying the Bayesian reference analysis of the Poisson model in the presence of background. It is used to write the form of the reference prior for the signal, in a model in which there is prior knowledge of the background. It has few nice properties, and I'm wondering if this polynomial is already known in the math l...
Article
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During the next solar maximum, two upcoming space-borne X-ray missions, STIX on board Solar Orbiter and MiSolFA, will perform stereoscopic X-ray observations of solar flares at two different locations: STIX at 0.28 AU (at perihelion) and up to inclinations of $\sim25^{\circ}$, and MiSolFA in a low-Earth orbit. The combined observations from these c...
Article
Full-text available
During a solar flare, a large fraction of the magnetic energy released goes into the kinetic energy of non-thermal particles, with X-ray observations providing a direct diagnostic tool of keV flare-accelerated electrons. However, the electron angular distribution, a prime diagnostic tool of the acceleration mechanism and transport, is poorly known....
Article
Neutrons travel along straight lines in free space, but only survive for a distance which depends on their energy. Thus, detecting neutrons in space in principle provides directional and distance information. Apart from secondary neutrons produced by cosmic-ray interactions in the Earth atmosphere, which are the dominant background, direct neutron...
Book
This textbook introduces thermodynamics using a unique and novel approach. Starting with four fundamental physical facts (the atomic nature of matter, the indistinguishability of atoms and molecules of the same species, the uncertainty principle, and the existence of equilibrium states), the behavior of complex systems is analyzed with the tools of...
Article
Full-text available
The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton–proton collisions at a centre-of-mass energy s=8 TeVat the Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb−1. The focus is on the contributions to W+ jetsprocesses from real W...
Article
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The luminosity determination for the ATLAS detector at the LHC during pp collisions at \(\sqrt{s} =\) 8 TeV in 2012 is presented. The evaluation of the luminosity scale is performed using several luminometers, and comparisons between these luminosity detectors are made to assess the accuracy, consistency and long-term stability of the results. A lu...
Article
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A test of CP invariance in Higgs boson production via vector-boson fusion using the method of the Optimal Observable is presented. The analysis exploits the decay mode of the Higgs boson into a pair of \(\tau \) leptons and is based on 20.3 \(\mathrm{fb}^{-1}\) of proton–proton collision data at \(\sqrt{s}\) = 8 \(\,\mathrm{TeV}\) collected by the...
Article
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The algorithms used by the ATLAS Collaboration to reconstruct and identify prompt photons are described. Measurements of the photon identification efficiencies are reported, using 4.9 fb\(^{-1}\) of pp collision data collected at the LHC at \(\sqrt{s} = 7\) \(\text {TeV}\) and 20.3 fb\(^{-1}\) at \(\sqrt{s} = 8\) \(\text {TeV}\). The efficiencies a...
Article
Full-text available
The dijet production cross section for jets containing a b-hadron (b-jets) has been measured in proton–proton collisions with a centre-of-mass energy of \(\sqrt{s} = 7\) TeV, using the ATLAS detector at the LHC. The data used correspond to an integrated luminosity of \(\mathrm 4.2\,\text {fb}^{-1}\). The cross section is measured for events with tw...
Article
Full-text available
A search for supersymmetry in events with large missing transverse momentum, jets, and at least one hadronically decaying tau lepton has been performed using 3.2 fb\(^{-1}\) of proton–proton collision data at \(\sqrt{s}=13{\mathrm {\ TeV}}\) recorded by the ATLAS detector at the Large Hadron Collider in 2015. Two exclusive final states are consider...
Article
Full-text available
Knowledge of the material in the ATLAS inner tracking detector is crucial in understanding the reconstruction of charged-particle tracks, the performance of algorithms that identify jets containing b-hadrons and is also essential to reduce background in searches for exotic particles that can decay within the inner detector volume. Interactions of p...
Article
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A search is presented for new resonances decaying to a W or Z boson and a Higgs boson in the ℓ+ℓ−bb¯, ℓνbb¯, and νν¯bb¯ channels in pp collisions at s=13 TeV with the ATLAS detector at the Large Hadron Collider using a total integrated luminosity of 3.2 fb⁻¹. The search is conducted by looking for a localized excess in the WH/ZH invariant or transv...
Article
Full-text available
A search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks is presented, using 3.2 fb⁻¹ of pp collisions at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC. The decay of the Higgs boson is reconstructed as a high-momentum bb¯ system with either a pair of small-radius j...
Article
This Letter presents a search for new resonances with mass larger than 250 GeV, decaying to a Z boson and a photon. The dataset consists of an integrated luminosity of 3.2 fb⁻¹ of pp collisions collected at s=13 TeV with the ATLAS detector at the Large Hadron Collider. The Z bosons are identified through their decays either to charged, light, lepto...
Article
Full-text available
Measurements of normalized differential cross sections of top quark pair (tt production are presented as a function of the mass, the transverse momentum and the rapidity of the tt system in proton-proton collisions at center-of-mass energies of s=7 and 8 TeV. The data set corresponds to an integrated luminosity of 4.6 fb-1 at 7 TeV and 20.2 fb-1 at...
Article
Full-text available
The large rate of multiple simultaneous proton– proton interactions, or pile-up, generated by the Large Hadron Collider in Run 1 required the development of many new techniques to mitigate the adverse effects of these conditions. This paper describes the methods employed in the ATLAS experiment to correct for the impact of pile-up on jet energy and...
Article
Full-text available
A search for neutral Higgs bosons of the minimal supersymmetric standard model (MSSM) and for a heavneutral Z boson is performed using a data sample corresponding to an integrated luminosity of 3.2 fb−1 from proton–proton collisions at √s = 13 TeV recorded by the ATLAS detector at the LHC. The heavy resonance is assumed to decay to a τ +τ − pair wi...
Article
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This paper presents a dedicated search for exotic decays of the Higgs boson to a pair of new spin-zero particles, \(H \rightarrow aa\), where the particle a decays to b-quarks and has a mass in the range of 20–60 GeV. The search is performed in events where the Higgs boson is produced in association with a \(W\) boson, giving rise to a signature of...
Article
Full-text available
The ATLAS measurement of the inclusive top quark pair (\(t\bar{t}\)) cross-section \(\sigma _{t\bar{t}}\) in proton–proton collisions at \(\sqrt{s}=8\) \(\,\mathrm{TeV}\) has been updated using the final 2012 luminosity calibration. The updated cross-section result is: $$\begin{aligned} \sigma _{t\bar{t}}= 242.9\pm 1.7\pm 5.5\pm 5.1\pm 4.2\,\mathrm...
Article
Full-text available
A search with the ATLAS detector is presented for the Standard Model Higgs boson produced by vector-boson fusion and decaying to a pair of bottom quarks, using 20.2 fb⁻¹ of LHC proton-proton collision data at s=8 TeV. The signal is searched for as a resonance in the invariant mass distribution of a pair of jets containing b-hadrons in vector-boson-...
Article
Full-text available
Inclusive four-jet events produced in proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=7 \) TeV are analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of 37.3 pb−1, collected with the ATLAS detector at the LHC. The contribution of hard double-parton scattering to the pro...
Article
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Measurements of the per-event charged-particle yield as a function of the charged-particle transverse momentum and rapidity are performed using p+Pb collision data collected by the ATLAS experiment at the LHC at a centre-of-mass energy of sNN=5.02 TeV. Charged particles are reconstructed over pseudorapidity |η|<2.3 and transverse momentum between 0...
Article
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This Letter presents a measurement of the inelastic proton-proton cross section using 60 μb−1 of pp collisions at a center-of-mass energy ffiffi s p of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.07<jηj<3.86) of the detector. A cross section of 68.1 1.4...
Article
Full-text available
A search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 fb(-1) of ppcollisions at root s = 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a Wor Z boson and with large missing transverse momentum are analysed. The data are consis...
Article
Full-text available
The production of W boson pairs in association with one jet in pp collisions at s=8 TeV is studied using data corresponding to an integrated luminosity of 20.3 fb⁻¹ collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The cross section is measured in a fiducial phase-space region defined by the presence of exactly one elec...
Article
Full-text available
A search is conducted for both resonant and non-resonant high-mass new phenomena in dielectron and dimuon final states. The search uses 3.2fb−1 of proton–proton collision data, collected at s=13TeV by the ATLAS experiment at the LHC in 2015. The dilepton invariant mass is used as the discriminating variable. No significant deviation from the Standa...
Article
Full-text available
The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce...
Article
Full-text available
Measurements of normalized differential cross-sections of top-quark pair production are presented as a function of the top-quark, \(t\bar{t}\) system and event-level kinematic observables in proton–proton collisions at a centre-of-mass energy of \(\sqrt{s}=8\,\mathrm{TeV}\). The observables have been chosen to emphasize the \(t\bar{t}\) production...
Article
Full-text available
The result of a search for pair production of the supersymmetric partner of the Standard Model bottom quark (\(\tilde{b}^{}_{1} \)) is reported. The search uses 3.2 fb\(^{-1}\) of pp collisions at \(\sqrt{s}=13\) TeV collected by the ATLAS experiment at the Large Hadron Collider in 2015. Bottom squarks are searched for in events containing large mi...
Article
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The results of a search for gluinos in final states with an isolated electron or muon, multiple jets and large missing transverse momentum using proton–proton collision data at a centre-of-mass energy of \(\sqrt{s} = 13 \mathrm{{\ Te V}}\) are presented. The dataset used was recorded in 2015 by the ATLAS experiment at the Large Hadron Collider and...
Article
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A search is performed for a heavy particle decaying into different flavour dilepton pairs (eμ, eτ or μτ), using 3.2 fb- 1 of proton–proton collision data at s=13 TeV collected in 2015 by the ATLAS detector at the Large Hadron Collider. No excess over the Standard Model prediction is observed. Limits at the 95 % credibility level are set on the mass...
Article
Full-text available
A search for bosons in events with one lepton (electron or muon) and missing transverse momentum is presented. The search uses 3.2 fb⁻¹ of pp collision data collected at by the ATLAS experiment at the LHC in 2015. The transverse mass distribution is examined and no significant excess of events above the level expected from Standard Model processes...
Article
Full-text available
The results of a search for the top squark, the supersymmetric partner of the top quark, in final states with one isolated electron or muon, jets, and missing transverse momentum are reported. The search uses the 2015 LHC pp collision data at a center-of-mass energy of s=13 TeV recorded by the ATLAS detector and corresponding to an integrated lumin...
Article
Full-text available
An inclusive search for a new-physics signature of lepton-jet resonances has been performed by the ATLAS experiment. Scalar leptoquarks, pair-produced in pp collisions at [$\sqrt{s}$] = 13 TeV at the large hadron collider, have been considered. An integrated luminosity of 3.2 fb⁻¹, corresponding to the full 2015 dataset was used. First (second) gen...
Article
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The production of W±Z events in proton–proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb−1. The W±Z candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross sect...
Article
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A search for Higgs-boson pair production in the bbb¯ b¯ final state is carried out with 3.2 fb−1 of protonproton collision data collected at ffiffi s p ¼ 13 TeV with the ATLAS detector. The data are consistent with the estimated background and are used to set upper limits on the production cross section of Higgs-boson pairs times branching ratio to...
Article
Full-text available
Searches for new resonances decaying into two photons in the ATLAS experiment at the CERN Large Hadron Collider are described. The analysis is based on proton-proton collision data corresponding to an integrated luminosity of 3.2 fb−1 at \( \sqrt{s}=13 \) TeV recorded in 2015. Two searches are performed, one targeted at a spin-2 particle of mass la...
Article
Full-text available
The production of W boson pairs in proton-proton collisions at \( \sqrt{s}=8 \) TeV is studied using data corresponding to 20.3 fb−1 of integrated luminosity collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The W bosons are reconstructed using their leptonic decays into electrons or muons and neutrinos. Events with rec...
Article
Full-text available
A selection of searches by the ATLAS experiment at the LHC for the electroweak production of SUSY particles are used to study their impact on the constraints on dark matter candidates. The searches use 20 fb−1 of proton-proton collision data at \( \sqrt{s}=8 \) TeV. A likelihood-driven scan of a five-dimensional effective model focusing on the gaug...
Article
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A study of the decays \(B^0_s \rightarrow \mu ^+\mu ^-\) and \(B^0 \rightarrow \mu ^+\mu ^-\) has been performed using data corresponding to an integrated luminosity of 25 fb\(^{-1}\) of 7 and 8 TeV proton–proton collisions collected with the ATLAS detector during the LHC Run 1. For the \(B^0\) dimuon decay, an upper limit on the branching fraction...
Article
Full-text available
A search has been made for supersymmetry in a final state containing two photons and missing transverse momentum using the ATLAS detector at the Large Hadron Collider. The search makes use of \(3.2{~\mathrm{fb}^{-1}}\) of proton-proton collision data collected at a centre-of-mass energy of 13 TeV in 2015. Using a combination of data-driven and Mont...
Article
Full-text available
Measurements of the jet activity in tt¯ events produced in proton-proton collisions at s=8 TeV are presented, using 20.3 fb⁻¹ of data collected by the ATLAS experiment at the Large Hadron Collider. The events were selected in the dilepton eμ decay channel with two identified b-jets. The numbers of additional jets for various jet transverse momentum...
Article
Full-text available
Measurements of distributions of charged particles produced in proton–proton collisions with a centre-of-mass energy of 13 TeV are presented. The data were recorded by the ATLAS detector at the LHC and correspond to an integrated luminosity of 151 μ b - 1. The particles are required to have a transverse momentum greater than 100 MeV and an absolute...
Article
Full-text available
Searches for new heavy resonances decaying to WW, WZ, and ZZ bosons are presented, using a data sample corresponding to 3.2 fb−1 of pp collisions at \( \sqrt{s}=13 \) TeV collected with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting ννqq, ℓνqq, ℓℓqq and qqqq final states are combined, searching for an arrow-width resonance...
Article
Full-text available
Searches for exclusively produced W boson pairs in the process pp(γγ)→pW+W-p and an exclusively produced Higgs boson in the process pp(gg)→pHp have been performed using e±μ final states. These measurements use 20.2 fb-1 of pp collisions collected by the ATLAS experiment at a center-of-mass energy s=8 TeV at the LHC. Exclusive production of W+W- con...
Article
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The top quark mass is measured in the tt¯→dilepton channel (lepton=e,μ) using ATLAS data recorded in the year 2012 at the LHC. The data were taken at a proton–proton centre-of-mass energy of s=8 TeV and correspond to an integrated luminosity of about 20.2 fb−1. Exploiting the template method, and using the distribution of invariant masses of lepton...
Article
Full-text available
This paper describes a measurement of the inclusive top quark pair production cross-section (σtt¯) with a data sample of 3.2fb−1 of proton–proton collisions at a centre-of-mass energy of s=13TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets conta...
Article
Full-text available
A measurement of the total pp cross section at the LHC at s=8 TeV is presented. An integrated luminosity of 500 μb−1 was accumulated in a special run with high-β⋆ beam optics to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t. The measurement is performed with the ALFA sub-detector of ATLA...
Article
Full-text available
A search for supersymmetry involving the pair production of gluinos decaying via third-generation squarks to the lightest neutralino (χ10) is reported. It uses an LHC proton-proton data set at a center-of-mass energy s=13 TeV with an integrated luminosity of 3.2 fb-1 collected with the ATLAS detector in 2015. The signal is searched for in events co...
Article
Full-text available
This paper presents a measurement of the double-differential cross section for the Drell-Yan Z/γ∗ → ℓ+ℓ− and photon-induced γγ → ℓ+ℓ− processes where ℓ is an electron or muon. The measurement is performed for invariant masses of the lepton pairs, mℓℓ, between 116 GeV and 1500 GeV using a sample of 20.3 fb−1 of pp collisions data at centre-of-mass e...