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First lifetime investigations of iodine isotopes: The quest for collectivity
No full textInternational audienceWe report on spectroscopic information and lifetime measurements in the neutron-rich I135,137,139 isotopes. This is the first lifetime data on iodine isotopes beyond N=82. Excited states were populated in fast neutron-induced fission of U238 at the ALTO facility of IJCLab with the LICORNE neutron source and detected using the hybrid ν-ball spectrometer. The level schemes of the I135,137,139 isotopes are revised in terms of excited states with up to maximum spin-parity of (33/2+), populated for the first time in fast neutron-induced fission. We provide first results on the lifetimes of the (9/21+) and (13/21+) states in I137 and I139, and the (17/21+) state in I137. In addition, we give upper lifetime limits for the (11/21+) states in I135−139, the (15/21+) state in I137, the (17/21+) state in I139, and reexamine the (29/21+) state in I137. The isomeric data in I135 are reinvestigated, such as the previously known (15/21+) and (23/21−) isomers with T1/2 of 1.64(14) and 4.6(7) ns, respectively, as obtained in this work. The new spectroscopic information is compared to that from spontaneous or thermal-neutron induced fission and discussed in the context of large scale shell-model (LSSM) calculations for the region beyond Sn132, indicating the behavior of collectivity for the three valence-proton iodine chain with N=82,84,86
New insights into the accessibility of native cellulose to environmental contaminants toward tritium behavior prediction
No full textInternational audienceTritium speciation and behavior in the environment directly rely on accessible OH groups of organic molecules and their hydrogen exchangeability properties. As one of the most widespread biomolecule, cellulose role in reducing the exchange capacity of the hydrogen atom has been previously highlighted experimentally in various environmental matrices. In this paper, a robust and reliable T/H gas-solid isotopic exchange procedure has been implemented to assess the OH group accessibility of native celluloses with an increasing degree of crystallinity. A linear relationship was found between hydroxyl reactivity and the crystallinity index (CrI) of native celluloses, as determined by the analysis of their crystalline structure from XRD characterization. The application of the obtained linear experimental model to cellulosic materials was then evaluated and an acceptable minimum value of 12% for the CrI parameter on environmental matrices could thus be established. The authors have therefore proposed an environmental matrices relevant and efficient analytical process in order to determine the accessibility of native cellulose hydroxyl groups to tritium in the environment from a single and quick sample characterization procedure
Overview of the Most Promising Radionuclides for Targeted Alpha Therapy: The “Hopeful Eight”
No full textInternational audienceAmong all existing radionuclides, only a few are of interest for therapeutic applications andmore specifically for targeted alpha therapy (TAT). From this selection, actinium-225, astatine-211,bismuth-212, bismuth-213, lead-212, radium-223, terbium-149 and thorium-227 are considered as themost suitable. Despite common general features, they all have their own physical characteristics thatmake them singular and so promising for TAT. These radionuclides were largely studied over thelast two decades, leading to a better knowledge of their production process and chemical behavior,allowing for an increasing number of biological evaluations. The aim of this review is to summarizethe main properties of these eight chosen radionuclides. An overview from their availability to theresulting clinical studies, by way of chemical design and preclinical studies is discussed
Modelling polonium complexes in solution
No full textNational audiencePolonium is one of the rarest and most toxic elements found in nature. Despite being discovered in 1898, it is still scarcely studied due to its dangerous properties. As far as one can understand, conducting experiments is not the safest way to shed light on it- even at trace concentrations, its most widely available isotope is lethal by ingestion or inhalation. Thus, knowledge of polonium chemistry is pretty narrow.The goal of this study is to predict the theoretical chemical behavior of polonium in solution without performing any experimental work, thus saving the experimenter’s health, lab equipment, and money. This is achieved by doing theoretical chemical calculations using methods of quantum mechanics.By using these, we investigate the behavior of polonium with two different ligands- water and chlorine ions, since the first type of complexes should be common in nature [1] and the second one has been experimentally reported [2]. Here we present our preliminary results regarding geometry, energies, and bond properties of the complexes calculated in the gas phase. This data is a base for further analysis of polonium chemistry in the solvent.[1] R. Ayala et al., J. Phys. Chem. B., 112 (2008): 5416-5422.[2] A. Stoïanov et al., Inorg. Chem., 58 (2019): 7036-7043
First measurement of quarkonium polarization in nuclear collisions at the LHC
No full textInternational audienceThe polarization of inclusive J/ψ and ϒ(1S) produced in Pb–Pb collisions at sNN=5.02 TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region 2.5<y<4 and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters λθ , λϕ and λθϕ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval 2<pT<10 GeV/ c and pT<15 GeV/ c for the J/ψ and ϒ(1S) , respectively. The polarization parameters for the J/ψ are found to be compatible with zero, within a maximum of about two standard deviations at low pT , for both reference frames and over the whole pT range. The values are compared with the corresponding results obtained for pp collisions at s=7 and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for ϒ(1S) production in Pb–Pb collisions are also consistent with zero
Transverse-momentum and event-shape dependence of D-meson flow harmonics in Pb–Pb collisions at = 5.02 TeV
No full textInternational audienceThe elliptic and triangular flow coefficients v2 and v3 of prompt D0 , D+ , and D⁎+ mesons were measured at midrapidity ( |y|<0.8 ) in Pb–Pb collisions at the centre-of-mass energy per nucleon pair of sNN=5.02TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays in the transverse momentum interval 1<pT<36GeV/c in central (0–10%) and semi-central (30–50%) collisions. Compared to pions, protons, and J/ψ mesons, the average D-meson vn harmonics are compatible within uncertainties with a mass hierarchy for pT≲3GeV/c , and are similar to those of charged pions for higher pT . The coupling of the charm quark to the light quarks in the underlying medium is further investigated with the application of the event-shape engineering (ESE) technique to the D-meson v2 and pT -differential yields. The D-meson v2 is correlated with average bulk elliptic flow in both central and semi-central collisions. Within the current precision, the ratios of per-event D-meson yields in the ESE-selected and unbiased samples are found to be compatible with unity. All the measurements are found to be reasonably well described by theoretical calculations including the effects of charm-quark transport and the recombination of charm quarks with light quarks in a hydrodynamically expanding medium
Production of light-flavor hadrons in pp collisions at
No full textInternational audienceThe production of , , , , , , , , , and their antiparticles was measured in inelastic proton–proton (pp) collisions at a center-of-mass energy of = 13 TeV at midrapidity () as a function of transverse momentum () using the ALICE detector at the CERN LHC. Furthermore, the single-particle distributions of , , and in inelastic pp collisions at TeV are reported here for the first time. The distributions are studied at midrapidity within the transverse momentum range GeV/c, depending on the particle species. The spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high with increasing collision energy is observed, which is similar for all particle species under study. The transverse mass and scaling properties of hadron production are also studied. As the collision energy increases from = 7–13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of , while ratios for multi-strange hadrons indicate enhancements. The -differential cross sections of , and () are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for and () at high
CATIROC: an integrated chip for neutrino experiments using photomultiplier tubes
No full textInternational audienceAn ASIC (Application Specific Integrated Chip) named CATIROC (Charge And Time Integrated Read Out Chip) has been developed for the next-generation neutrino experiments using a large number of photomultiplier tubes (PMTs). Each CATIROC provides the time and the charge measurements for 16 configurable input channels operating in auto-trigger mode. Originally designed for the light emission in water Cherenkov detectors, we show in this paper that its use can be extended to liquid-scintillator based experiments. The ∼ 26000 3-inch PMTs of the JUNO experiment, under construction in China, is a case in point. This paper describes the features of CATIROC with a special attention to the most critical points for its application to the time profile of the light emission in liquid scintillators. The achieved performances in both charge and time measurements can be inputs for future high-precision experiments making use of PMTs or other photo-sensitive detectors
production in and in -Pb collisions at =5.02 TeV
No full textInternational audienceThe production cross section of prompt charm baryons was measured with the ALICE detector at the LHC at midrapidity in proton-proton (pp) and proton-lead (p-Pb) collisions at a centre-of-mass energy per nucleon pair of TeV. The and baryons were reconstructed in the hadronic decay channels and and respective charge conjugates. The measured differential cross sections as a function of transverse momentum () and the -integrated production cross section in pp and in p-Pb collisions are presented. The nuclear modification factor (), calculated from the cross sections in pp and in p-Pb collisions, is presented and compared with the of D mesons. The ratio is also presented and compared with the light-flavour baryon-to-meson ratios p and , and measurements from other LHC experiments. The results are compared to predictions from model calculations and Monte Carlo event generators
Shear viscosity and electric conductivity of a hot and dense QGP with a chiral phase transition
No full textInternational audienceWe calculate two transport coefficients—the shear viscosity over entropy ratio η/s and the ratio of the electric conductivity to the temperature, σ0/T—of strongly interacting quark matter within the extended Nf=3 Polyakov Nambu-Jona-Lasinio (PNJL) model along the crossover transition line for moderate values of baryon chemical potential 0≤μB≤0.9GeV as well as in the vicinity of the critical endpoint (CEP) and at large baryon chemical potential μB=1.2GeV, where the first-order phase transition takes place. The evaluation of the transport coefficients is performed on the basis of the effective Boltzmann equation in the relaxation time approximation. We employ two different methods for the calculation of the quark relaxation times: (i) using the averaged transition rate defined via thermal averaged quark-quark and quark-antiquark PNJL cross sections and (ii) using the “weighted” thermal averaged quark-quark and quark-antiquark PNJL cross sections. The η/s and σ0/T transport coefficients have similar temperature and chemical potential behaviors when approaching the chiral phase transition for both methods for the quark relaxation time; however, the differences grow with increasing temperature. We demonstrate the effect of the first-order phase transition and of the CEP on the transport coefficients in the deconfined QCD medium