News & Highlighted Publications

Une nouvelle étape a été franchie par SPIRAL2 !

Pour la première fois la semaine dernière, les protons ont été accélérés jusqu’au bout de l’accélérateur, et ont atteint leur énergie nominale de 33 MeV. Rien de mieux qu’une image pour s’en persuader ! Le cycle utile, donc la puissance moyenne, reste certes modeste, mais il augure déjà l’objectif du premier faisceau dans NFS dans les tout prochains jours. Depuis l’autorisation ASN, c’est une véritable accélération des jalons franchis concernant la qualification de cet accélérateur. Ce projet majeur pour la (...)

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ALICE Upgrade: rejuvenating the wire chambers

The ALICE muon spectrometer [1] consists of 5 tracking stations and 2 triggering stations which detect charged particles and determines their trajectories to allow energy/momentum calculations. Amongst the charged particles, muons are of particular interest since they may originate from charm (...)

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LINO at ALTO passed the test run successfully

Laser spectroscopy is an experimental technique probing the minute splitting of atomic energy levels, or hyperfine structure, induced by the nuclear electromagnetism. To achieve such precision, narrow-band lasers are used, and the atom-laser interaction is performed in-flight on a fast atomic beam. At the ALTO laboratory, singly-charged ions were first accelerated to an energy of 30 keV, then passed through a volume of vaporized sodium for neutralization and overlapped with a (...)

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Journées européennes du Patrimoine 2019

Journées européennes du Patrimoine : Dimanche 22 septembre après-midi, malgré la pluie, une quarantaine de personnes sont venues visiter le Linac. Cette impressionnante structure de cuivre, qui avait été la 1ere classée monument historique dans la catégorie instrument scientifique, est exposée sous vitrine extérieure en libre accès près du bâtiment 100 de l’IPN d’Orsay. Les visiteurs ont bénéficié des explications personnalisées de Denis Jouan, chercheur CNRS et chargé de mission Patrimoine à l’IPN. Ce (...)

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Probing dense baryon-rich matter with virtual photons

About 10 μs after the Big Bang, the universe was filled—in addition to photons and leptons—with strong-interaction matter consisting of quarks and gluons, which transitioned to hadrons at temperatures close to kT = 150 MeV and densities several times higher than those found in nuclei. This quantum (...)

A. Belounnas, T. Hennino, B. Ramstein, F. Scozzi

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ALICE Upgrade: jouvence des chambre à fils construites à l’IPN Orsay

ALICE detector is going through a major upgrade phase to enhance its readout speed at a level where ALICE will be capable to record all lead lead collisions produced at the LHC from 2021. A gain of a factor of 100 with respect to the current electronic is needed for the readout of the Muon (...)

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Tetraquark-adequate formulation of QCD sum rules

We study details of QCD sum rules à la Shifman-Vainshtein-Zakharov for exotic tetraquark states. We point out that duality relations for correlators involving exotic currents have fundamental differences compared with the duality relations for the correlators of bilinear quark currents : namely, the O(1) and O(αs) (αs the strong coupling constant) terms in the operator product expansion for the exotic correlators exactly cancel against the contributions of the two-meson states on the hadron (...)

Wolfgang Lucha, Dmitri Melikhov, Hagop Sazdjian

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Tetraquark-adequate QCD sum rules for quark-exchange processes

We consider quark-hadron duality relations and QCD sum rules for correlators involving exotic tetraquark currents, here specializing to the case of quark-exchange processes. We point out the differences they exhibit with respect to the cases involving ordinary bilinear quark currents. Based on the observation that only diagrams possessing at least four-quark singularities can contribute to the formation of tetraquark states, we show that the quark-hadron duality relations and the (...)

Wolfgang Lucha, Dmitri Melikhov, and Hagop Sazdjian

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Design and characterization of a single photoelectron calibration system for the NectarCAM camera of the medium-sized telescopes of the Cherenkov Telescope Array

Abstract In this work, we describe the optical properties of the single photoelectron (SPE) calibration system designed for NectarCAM, a camera proposed for the Medium Sized Telescopes (MST) of the Cherenkov Telescope Array (CTA). One of the goals of the SPE system, as integral part of the NectarCAM camera, consists in measuring with high accuracy the gain of its photo-detection chain. The SPE system is based on a white painted screen where light pulses are injected through a (...)

Barbara Biasuzzi, Kevin Pressard, Jonathan Biteau, Brice Geoffroy, Carlos Domingues Goncalves, Giulia Hull, Miktat Imre, Michaël Josselin, Alain Maroni, Bernard Mathon, Lucien Seminor, Tiina Suomijarvi, Thi Nguyen Trung, Laurent Vatrinet

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Soft breathing modes in neutron-rich nuclei with the subtracted second random-phase approximation

We analyze the isoscalar response related to breathing modes with particular attention being paid to low-lying excitations in neutron-rich nuclei. We use the subtracted second random-phase approximation (SSRPA) to describe microscopically the response. By increasing the neutron excess, we study the evolution of the response in Ca isotopes going from 40Ca to 48Ca and to 60Ca as well as in N=20 isotones going from 40Ca to 36S (...)

D. Gambacurta, M. Grasso, and O. Sorlin

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Nuclear jets in heavy-ion collisions

Head-on collisions between nuclei of different size at Fermi energies may give rise to extremely deformed dynamical regimes and patterns. Those latter, may suddenly turn into a stream of nuclear clusters, resembling collimated jets. This mechanism, which could be easily addressed in experiments, is simulated in the framework of stochastic one-body approaches. We employ the Boltzmann-Langevin equation to specifically address out-of-equilibrium conditions and handle dynamical fluctuations. (...)

P.Napolitani, M.Colonna

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Detection properties and internal activity of newly developed La-containing scintillator crystals

In this work we will present the characterization, in terms of gamma response and internal activity of newly developed crystals that contains Lanthanum in their chemical formula. In particular we tested two LaBr3:Ce,Sr, one CLLBC and two CLLB crystals with different volumes. These crystals just overcome the prototype stage and, even if the production in still not standardized at least for large optics, they have been very recently commercialized in sizes interesting for high-energy (...)

Giulia Hull, Michaël Josselin

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Study of light yield for different configurations of plastic scintillators and wavelength shifting fibers

Abstract In the effort of the AugerPrime scintillator surface detector R&D activity, we investigated the performances of different extruded and cast plastic scintillators that were read out with wavelength-shifting (WLS) optical fibers and then coupled to a PMT. In particular we compared the light yield of eighteen scintillator/fiber configurations, obtained combining eight different scintillator bars with six fiber types, in order to investigate which was satisfying the AugerPrime (...)

Giulia Hull, Miktat Imre, Michaël Josselin, Alain Maroni, Tiina Suomijärvi

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