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Beta Decay of Ga Studied at the ALTO Facility
No full textInternational audienceExcited states in the N = 50 nucleus 82Ge have been investigated via beta decay of 82Ga at the ALTO facility. More than 50 new gamma transitions were identified. The preliminary results are presented in this work
Prospects for quarkonium studies at the high-luminosity LHC
No full textInternational audienceProspects for quarkonium-production studies accessible during the upcoming high-luminosity phases of the CERN Large Hadron Collider operation after 2021 are reviewed. Current experimental and theoretical open issues in the field are assessed together with the potential for future studies in quarkonium-related physics. This will be possible through the exploitation of the huge data samples to be collected in proton–proton, proton–nucleus and nucleus–nucleus collisions, both in the collider and fixed-target modes. Such investigations include, among others, those of: (i) J/ψ and Υ produced in association with other hard particles; (ii) χc,b and ηc,b down to small transverse momenta; (iii) the constraints brought in by quarkonia on gluon PDFs, nuclear PDFs, TMDs, GPDs and GTMDs, as well as on the low-x parton dynamics; (iv) the gluon Sivers effect in polarised-nucleon collisions; (v) the properties of the quark–gluon plasma produced in ultra-relativistic heavy-ion collisions and of collective partonic effects in general; and (vi) double and triple parton scatterings
High Energy Physics Opportunities Using Reactor Antineutrinos
No full textInternational audienceNuclear reactors are uniquely powerful, abundant, and flavor-pure sources of antineutrinos that continue to play a vital role in the US neutrino physics program. The US reactor antineutrino physics community is a diverse interest group encompassing many detection technologies and many particle physics topics, including Standard Model and short-baseline oscillations, BSM physics searches, and reactor flux and spectrum modeling. The community's aims offer strong complimentary with numerous aspects of the wider US neutrino program and have direct relevance to most of the topical sub-groups composing the Snowmass 2021 Neutrino Frontier. Reactor neutrino experiments also have a direct societal impact and have become a strong workforce and technology development pipeline for DOE National Laboratories and universities. This white paper, prepared as a submission to the Snowmass 2021 community organizing exercise, will survey the state of the reactor antineutrino physics field and summarize the ways in which current and future reactor antineutrino experiments can play a critical role in advancing the field of particle physics in the next decade
Excitation functions of deuteron induced nuclear reactions on dysprosium targets for the production of the theranostic relevant isotopes of terbium
No full textInternational audienceThe physical properties of 149,152,155,161 Tb enable their use in both diagnostic and therapeutic applications in the field of nuclear medicine. For this reason the optimization of the production routes of these radionuclides is of widespread interest in research. In this work, the feasibility of the production of 155 Tb and 161 Tb via the nuclear reactions induced by deuterons on dysprosium target with natural isotopic abundances has been discussed. The cross sections of nat Dy(d,x) reactions have been studied in the 12.5–32 MeV energetic range with the stacked-foil technique and the corresponding Thick Target Yields have been obtained. The presence of terbium and dysprosium contaminants (156,160 Tb, 155,157,159 Dy) has been evaluated too
Classical vs. Quantum Corrections to Jet Broadening in a Weakly Coupled Quark-Gluon Plasma
No full textInternational audienceThe transverse momentum broadening coefficient serves to partly characterise the quenching of a jet as it propagates through the Quark-Gluon Plasma. While leading order value of this coefficient was calculated in the early 2000’s, it has since been realised to receive quantum, radiative corrections featuring potentially large logarithmic enhancements at relative order g^2. It is still not clear how these corrections compare quantitatively with their classical counterparts, i.e those coming from the exchange of thermal gluons with large occupation number, present at relative order g and g^2.During the course of the talk, we plan to first give some insight to the physical meaning of the transverse momentum broadening coefficient before moving on to motivate the need for a more careful calculation of these logarithmic corrections. We will then conclude by discussing some of our progress on such a calculation and how it fits within this overall goal of determining which class of corrections are more important
Le Beam Energy Scan au travers d’EPOS 4: Étude de l’impact des cascades hadroniques sur les cumulants d’ordre 2 des charges nettes conservées dans les collisions d’ions lourds
No full textDuring the last two decades, heavy-ion collisions at ultra-relativistic energies have been used to investigate the properties of the Quark-Gluon Plasma (QGP), a state of matter in which quarks & gluons are deconfined from hadrons. One of the major goals of this research is to map the phase diagram of nuclear matter, made possible experimentally thanks to the Beam Energy Scan (BES) program. It is performed, among other objectives, to search for a 1st order phase transition and a critical endpoint between QGP and hadron gas phases. Ratios of net-multiplicities cumulants has been shown to be relevant experimental proxies for such study, due to their link with thermodynamic susceptibilities. In this regard, the STAR collaboration has recently published measurements of the 2nd order cumulants of net-multiplicities for pions, kaons and protons in Au+Au collisions at several energies of the BES program. However, signatures from a 1st order transition or a critical point may be blurred out by the last stages of the collision. Taking advantage of the modular conception of the EPOS event generator, the impact of the hadronic cascades on these 2nd order cumulants has been studied. The STAR proxies results are also compared with the 2nd order cumulants of the corresponding conserved charges, and with enhanced proxies proposed by the authors of a study based on lattice quantum chromodynamics calculations and the use of a Hadron Resonance Gas model. This work takes place in the context of developments for a new version of EPOS, what requires to validate its reliability by comparing simulations with experimental data for a wide range of systems and beam energies. The integration of the RIVET analysis toolkit, which has been achieved to facilitate this validation process, is also presented in this thesis.Les collisions d’ions lourds aux énergies ultrarelativistes ont été utilisées durant les vingt dernières années afin d’étudier les propriétés du Plasma de Quarks & Gluons (PQG), un état de la matière où quarks et gluons sont déconfinés des hadrons. Un objectif de ces recherches est de cartographier le diagramme de phase de la matière nucléaire, rendu possible expérimentalement grâce au programme du Beam Energy Scan (BES). Il est réalisé, entre autres, afin de chercher des signatures d’une transition de 1er ordre et d’un point critique entre les phases de PQG et de gaz hadronique. Les ratios de cumulants de multiplicité nette ont ainsi été proposés comme grandeurs de procuration (proxies) de choix, de par leur lien avec les susceptibilités thermodynamiques. La collaboration STAR a ainsi publié récemment la mesure des cumulants d’ordre 2 de multiplicité nette des pions, kaons et protons dans les collisions Au+Au à différentes énergies du programme BES. Cependant, les signatures d’une transition de 1er ordre ou d’un point critique pourraient être modifiées par les derniers stades de la collision. Profitant de la conception modulaire du générateur d’événement EPOS, l’impact des cascades hadroniques sur ces cumulants d’ordre 2 a été étudié. Les résultats des proxies de STAR sont également comparés aux cumulants d’ordre 2 des charges conservées correspondantes, ainsi qu’à de meilleurs proxies proposés par les auteurs d’une étude basée sur des calculs de chromodynamique quantique sur réseau et l’utilisation d’un modèle de gaz de résonances hadroniques. Ce travail prend place dans le développement d’une nouvelle version d’EPOS, qui requiert de valider sa fiabilité en comparant les résultats de simulations aux données expérimentale pour un large panel de systèmes et d’énergies de faisceau. L’intégration du logiciel d’analyse RIVET, effectué afin de faciliter ce processus de validation, est également détaillée dans cette thèse
Quarkonium production and elliptic flow in small systems measured with ALICE
No full textInternational audience. Quarkonium production in hadronic collisions provides a unique testing ground for understanding quantum chromodynamics (QCD) since it involves both perturbative and non-perturbative regimes of this theory. A variety of experimental observables, such as the production cross-section, polarization, particle correlations, serve as insights into the phenomenology of the quarkonium production and help constrain the theoretical models. Measurements of quarkonia as a function of multiplicity probe multiple parton interactions (MPI), i.e., several parton-parton interactions occurring in a single hadron-hadron collision. Finally, measurements of the azimuthal correlation structure of emitted particles in high multiplicity pp collisions can probe the existence of collective behaviour in small systems. The ALICE detector can reconstruct inclusive quarkonia over a broad kinematical range, spanning from mid-rapidity up to forward rapidity, and down to zero transverse momentum. In addition, at midrapidity, the non-prompt charmonium contribution can be separated from the prompt contribution. In these proceedings, we present new results on the inclusive, prompt and non-prompt J/ψ production cross sections measured by ALICE in pp collisions at different collision energies. The self-normalized ψ(2S)-to-J/ψ yield ratio measurement is investigated as a function of the charged particle multiplicity in pp collisions at √S = 13. TeV. Finally, the first measurement of the J/ψ elliptic flow (v2) in high multiplicity pp collisions at √S = 13. TeV is presented. Results will be compared to theoretical models
Determining the neutrino mass ordering and oscillation parameters with KM3NeT/ORCA
No full textInternational audienceThe next generation of water Cherenkov neutrino telescopes in the Mediterranean Sea are under construction offshore France (KM3NeT/ORCA) and Sicily (KM3NeT/ARCA). The KM3NeT/ORCA detector features an energy detection threshold which allows to collect atmospheric neutrinos to study flavour oscillation. This paper reports the KM3NeT/ORCA sensitivity to this phenomenon. The event reconstruction, selection and classification are described. The sensitivity to determine the neutrino mass ordering was evaluated and found to be 4.4 if the true ordering is normal and 2.3 if inverted, after 3 years of data taking. The precision to measure and were also estimated and found to be and for normal neutrino mass ordering and, and for inverted ordering. Finally, a unitarity test of the leptonic mixing matrix by measuring the rate of tau neutrinos is described. Three years of data taking were found to be sufficient to exclude event rate variations larger than 20% at level
Spin(7) and generalized SO(8) instantons in eight dimensions
No full textInternational audienceWe present a simple compact formula for a topologically nontrivial map S7→Spin(7) associated with the fiber bundle Spin(7)→G2S7. The homotopy group π7[Spin(7)]=Z brings about the topologically nontrivial 8-dimensional gauge field configurations that belong to the algebra spin(7). The instantons are special such configurations that minimize the functional ∫Tr{F∧F∧⋆(F∧F)} and satisfy non-linear self-duality conditions, F∧F=±⋆(F∧F). Spin(7)⊂SO(8), and Spin(7) instantons represent simultaneously SO(8) instantons of a new type. The relevant homotopy is π7[SO(8)]=Z×Z, which implies the existence of two different topological charges. This also holds for all groups SO(4n) with integer n. We present explicit expressions for two topological charges and calculate their values for the conventional 4-dimensional and 8-dimensional instantons and also for the 8-dimensional instantons of the new type. Similar constructions for other algebras in different dimensions are briefly discussed