Etude de pièces anciennes par analyse PIXE. Comparaison avec d'autres techniques

Des pièces de monnaie anciennes de trois espèces différentes (gauloises, romaines, hammadites) ont été analysées par émission de rayons X induite par particules chargées (PIXE). Des études par microsonde électronique et activation par neutrons lents et rapides ont permis une comparaison des diverses techniques pour préciser les informations et compléter les résultats expérimentaux. Dans cet article nous présentons les conclusions d'intérêt archéologique qui peuvent être extraites de ces différentes applications de la physique

Tests and foreseen developments of fibered-OSLD gamma heating measurements in low-power reactors

International audienceIn this paper are presented test measurements of a fibered-OSLD system performed during a dedicated experimental phase in EOLE zero-power reactor. The measurement setup consists of an OSLD crystal connected onto the extremity of an optical fiber and a laser stimulation system, manufactured by the CEA/LIST in Saclay. The OSL sensor is remotely stimulated via an optical fiber using a diode-pumped solid-state laser. The OSL light is collected and guided back along the same fiber to a photomultiplier tube. Results obtained using this system are compared to usual gamma heating measurement protocol using OSLD pellets. The presence of induced radio-luminescence in the OSLD during the irradiation was also observed and could be used to monitor the gamma flux.The feasibility of remote measurements is achieved, whereas further developments could be conducted to improve this technique since the readout procedure still requires to withdraw the OSLD off the gamma flux (hence from the core) on account of the dose rate (around a few Gy.h-1), and the readout time remains quite long for on-line applications. Several improvements are foreseen, and will be tested in the forthcoming years

Early (Ti, Zr)-late (Rh, Ir) heteronuclear complexes with bridging sulphido ligands

[EN]: We report in this account on the controlled synthesis of novel d0-d8 early-late heteropolynuclear diolefin and carbonyl clusters. The synthetic approach was based on additive-deprotonation reactions involving the titanium and zirconium bis-hydrosulphido complexes of formula [Cp2Ti(SH)2] and [Cptt 2Zr(SH)2] and appropriate rhodium and iridium diolefin and carbonyl compounds. The significant differences between the resulting early-late complexes and their structures coming from the titanium or zirconium metalloligand precursors are highlighted. The catalytic activity of some representative titanium-rhodium and zirconium-rhodium compounds towards alkene hydroformylation was explored. Interestingly, the heterotetranuclear 'CpTi(μ3-S)3Rh3' structure was maintained as such under mild conditions.[FR]: Nous rapportons dans cet article la préparation contrôlée de nouveaux clusters hétéropolynucléaires early-late d0–d8 portant les ligands oléfine et carbonyle. La réaction de déprotonation–addition a été la méthode de synthèse utilisée et implique la condensation de complexes bis-hydrogénosulfure du titane et du zirconium, de formule [Cp2Ti(SH)2] et [Cptt2Zr(SH)2], sur les composés adéquats du rhodium et de l’iridium portant les ligands oléfine et carbonyle. Les différences significatives de structure entre les complexes early-late ainsi préparés, dues à la nature du métalloligand précurseur du titane ou du zirconium employé, sont mises en évidence. L’activité catalytique de quelques composés représentatifs titane–rhodium et zirconium–rhodium dans l’hydroformylation d’alcènes a été mesurée. Il convient de noter que la structure hétérotétranucléaire « CpTi(μ3-S)3Rh3 » est maintenue comme telle sous des conditions douces de réaction.Peer Reviewe

The anions [Cptt2Zr(μ-S)2M(CO)2]- (M = Rh, Ir) as versatile precursors for the synthesis of sulfido-bridged early−late heterotrimetallic (ELHT) compounds

The reaction of [Cp2 ttZr(μ3-S) 2{Ir(CO)2}2] (Cptt = η5-1,3-di-tert-butylcyclopentadienyl) with dppe (1,2-bis-(diphenylphosphino)ethane) affords the ion-pair compound [Ir(CO)(dPPe)2][Cp2 ttZr(μ-S) 2Ir(CO)2] (2). The related compound [Rh(dPPe) 2][Cp2 ttZr(μ-S)2Rh(CO) 2] (5) has been obtained in solution under a carbon monoxide atmosphere by reaction of [Cp2 ttZr(μ3-S) 2{Rh(CO)2}2] with dppe through the intermediate heterotrinuclear compound [Cp2 ttZr(μ3-S) 2{Rh(dppe)}{Rh(CO)2}] (4). Reaction of the heterodinuclear anion [Cp2 ttZr(μ-S)2Ir(CO) 2]-, generated in situ, with [Rh(μ-Cl)(cod)] 2, [RhCl2(CO)2]- and [Pd(μ-Cl)-(η3-C3H5)]2 affords the d0-d8-d8 early-late compounds [Cp 2 ttZr(μ3-S)2{Ir(CO) 2}{Rh(cod)}] (6), [Cp2 tt-Zr(μ3-S) 2{Ir(CO)2}{Rh(CO)2}] (7), and [Cp 2 ttZr(μ3-S)2{Ir(CO) 2}{Pd(η3-C3H5)}] (8) each with a symmetrical trigonal-bipyramidal M3(μ3-S)2 heterotrimetallic metal-sulfur core. In the same way, the reaction of [Cp 2 ttZr(μ-S)2M(CO)2]- (M = Rh, Ir) with [AuCl(PPh3)] leads to the preparation of the d 0-d8-d10 early-late compounds [Cp 2 ttZr(μ-S)2(Ir(CO)2}{Au(PPh 3)}] (9) and [Cp2 ttZr(μ-S) 2{Rh(CO)2}{Au(PPh3)}] (10) with an open M 3(μ3-S)(μ2-S) heterotrimetallic metal-sulfur framework. On the other hand, treatment of the bis(hydrosulfido) zirconium compound [Cp2 ttZr(SH)2] with triethylamine followed by addition of [Pd(μ-Cl)(η3-C 3H5)]2 or [AuCl(PPh3)] affords the sulfido-bridged early-late heterobimetallic compounds [Cp2 ttZr(μ3-S)2{Pd(η3-C 3H5)}2] (11) and [Cp2 ttZr(μ-S)2(Au(PPh3)}2] (12). The molecular structure of complexes 9 and 12 determined by X-ray diffraction methods are also described.The financial support from Ministerio de Educación y Ciencia (MEC/FEDER) is gratefully acknowledged (Projects CTQ2006-03973/BQU and Factoría de Cristalización, CONSOLIDER INGENIO-2010).Peer Reviewe

JPCam: A 1.2Gpixel camera for the J-PAS survey

JPCam is a 14-CCD mosaic camera, using the new e2v 9k-by-9k 10microm-pixel 16-channel detectors, to be deployed on a dedicated 2.55m wide-field telescope at the OAJ (Observatorio Astrofisico de Javalambre) in Aragon, Spain. The camera is designed to perform a Baryon Acoustic Oscillations (BAO) survey of the northern sky. The J-PAS survey strategy will use 54 relatively narrow-band (~13.8nm) filters equi-spaced between 370 and 920nm plus 3 broad-band filters to achieve unprecedented photometric red-shift accuracies for faint galaxies over ~8000 square degrees of sky. The cryostat, detector mosaic and read electronics is being supplied by e2v under contract to J-PAS while the mechanical structure, housing the shutter and filter assembly, is being designed and constructed by a Brazilian consortium led by INPE (Instituto Nacional de Pesquisas Espaciais). Four sets of 14 filters are placed in the ambient environment, just above the dewar window but directly in line with the detectors, leading to a mosaic having ~10mm gaps between each CCD. The massive 500mm aperture shutter is expected to be supplied by the Argelander-Institut fur Astronomie, Bonn. We will present an overview of JPCam, from the filter configuration through to the CCD mosaic camera. A brief outline of the main J-PAS science projects will be included.Comment: 11 pages and 9 figure

Reversible opening of the triangular structure of a sulfido-bridged ZrRh2 early-late heterobimetallic complex induced by Bis-(diphenylphosphino)methane

Reaction of the early - late heterobimetallic complexes [Cp tt 2Zr(μ3-S)2{M(CO)} 2(μ-dppm)] (M = Rh, Ir) with dppm (bis-(diphenylphosphino)methane) yields the compounds [Cptt 2Zr(μ-S)2M(μ- CO)2(μ-dppm)M(η2-dppm)] (M = Rh (3), Ir (4)). The molecular structure of 3 shows a bent trimetallic ZrRhRh chain with tetrahedral, trigonal-bipyramidal, and square-pyramidal geometries, respectively. This trinuclear compound exhibits a mixed-valence Rh(II) - Rh(0) metal - metal bonded unit that results from the unusual chelating coordination of the metalloligand [Cptt 2Zr(S)2]2- and is further stabilized by the presence of two unsymmetrical bridging carbonyl ligands, which interact with the unsaturated Rh(II) metal. The formation of 3 is reversible, and the equilibrium 1 + dppm ⇄ 3 has been observed in solution (K ≈ 16 at 22 °C in C6D6). The opening of the triangular core in the heterotrimetallic compound [Cptt 2Zr(μ 3-S)2-{Rh(CO)}{Ir(CO)}(μ-dppm)] (5) is not selective and gives the compounds [Cptt 2Zr(μ-S) 2Rh(μ-CO)2(μ-dppm)Ir(η2-dppm)] (6) and [Cptt 2Zr(μ-S)2Ir(μ-CO) 2(μ-dppm)Rh(η2-dppm)] (7) in a 3:1 molar ratio.The generous financial support from Dirección General de Enseñanza Superior e Investigación (DGES) (Project BQU2003-05412-C02-01) is gratefully acknowledged.Peer Reviewe

Synthesis, reactivity, and catalytic activity of triangular ZrM2 (M = Rh, Ir) early-late heterobimetallic complexes

Reactions of the zirconium−sulfide metallocene anion [Cptt2ZrS2]2- (Cptt = η5-1,3-di-tert-butylcyclopentadienyl) with [{M(μ-Cl)(diolefin)}2 gave the d0−d8 complexes [Cptt2Zr(μ3-S)2{M(diolefin)}2] (M = Rh, diolefin = 2,5-norbornadiene (nbd) (1), 1,5-cyclooctadiene (cod); M = Ir, diolefin = cod) with a triangular ZrM2 core capped by two symmetrical μ3-sulfido ligands. The rhodium complexes [Cptt2Zr(μ3-S)2{Rh(diolefin)}2] (diolefin = tetrafluorobenzobarrelene (tfbb), nbd, cod) can also be prepared by the additive-deprotonation reactions of the mononuclear [Rh(acac)(diolefin)] (diolefin = nbd, tfbb) and the dinuclear [{Rh(μ-OH)(cod)}2] complexes with [Cptt2Zr(SH)2]. These compounds exist as two rotamers in solution due to a hindered rotation of the cyclopentadienyl rings and the relative disposition of the substituents of the Cptt groups in the sandwich moiety. The reaction of [Cptt2Zr(SH)2] with [Ir(acac)(cod)] gave the complex [Cptt(acac)Zr(μ3-S)2{Ir(cod)}2] (5) with release of HCptt and coordination of acetylacetonate to the zirconium center. Carbonylation of compounds 1 and 5 yielded [Cptt2Zr(μ3-S)2{Rh(CO)2}2] (6) and [Cptt(acac)Zr(μ3-S)2{Ir(CO)2}2], respectively, while the complexes [Cptt2Zr(μ3-S)2{M(CO)2}2] (M = Rh, Ir) resulted also from the reaction of [Cptt2Zr(SH)2] with (PPh3Bz)[MCl2(CO)2] in the presence of triethylamine. Reactions of the carbonyl complexes with 1 molar equiv of bis(diphenylphosphino)methane (dppm) gave the cisoid complexes [Cptt2Zr(μ3-S)2{M(CO)}2(μ-dppm)] (M = Rh (9), Ir) with evolution of carbon monoxide. Monodentate phosphites, P(OMe)3 and P(OPh)3, react with 6 to give mixtures of the transoid and cisoid isomers [Cptt2Zr(μ3-S)2{Rh(CO)(P(OR)3)}2], which also exhibit a restricted rotation of the Cptt rings. The molecular structures of complexes 6 and 9 have been determined by X-ray diffraction methods. Compound 6 in the presence of P-donor ligands, P(OMe)3, P(OPh)3, and PPh3, is a precursor of the catalyst for the hydroformylation of oct-1-ene under mild conditions of pressure and temperature. No Zr−Rh synergic effect is observed in this case, and the precursor breaks down after catalysis.We wish to thank Dirección General de Enseñanza Superior (DGES) and Diputación General de Aragón (DGA) for financial support (Projects PB88–0641 and P051/2000, respectively). Fellowships from the Ministerio de Educación y Cultura (M.A.F.H.-G.), Diputación General de Aragón (I.T.D.) and Programa CYTED (A.B.R.) are gratefully acknowledged.Peer Reviewe

Spectrophotometric study in the near-ir of a sample of MIPS selected galaxies at Z~2

Our main objective is to determine what kind of galaxies dominate the cosmic SFR density at z~2. Our sample consists of 24 galaxies in Chandra Deep Field South, a unique field for the study of galaxy evolution (12 observed with GNIRS/GEMINI and 12 with ISAAC/VLT). We use H alpha together with the already merged X-ray, ultraviolet, optical, near and mid-infrared imaging data to obtain estimations of SFRs, metallicities, stellar and dynamical masses, AGN activity, and extinction properties. We have obtained 15 Hα detections, 4 rotation curves, and SFR relationship for 7 galaxies. The metallicities obtained for 8 galaxies of the sample are compatible with the metallicities of local galaxies

Stellar populations of galaxies in the ALHAMBRA survey up to z∼1z \sim 1. I. MUFFIT: A Multi-Filter Fitting code for stellar population diagnostics

We present MUFFIT, a new generic code optimized to retrieve the main stellar population parameters of galaxies in photometric multi-filter surveys, and we check its reliability and feasibility with real galaxy data from the ALHAMBRA survey. Making use of an error-weighted $\chi^2$-test, we compare the multi-filter fluxes of galaxies with the synthetic photometry of mixtures of two single stellar populations at different redshifts and extinctions, to provide through a Monte Carlo method the most likely range of stellar population parameters (mainly ages and metallicities), extinctions, redshifts, and stellar masses. To improve the diagnostic reliability, MUFFIT identifies and removes from the analysis those bands that are significantly affected by emission lines. We highlight that the retrieved age-metallicity locus for a sample of $z \le 0.22$ early-type galaxies in ALHAMBRA at different stellar mass bins are in very good agreement with the ones from SDSS spectroscopic diagnostics. Moreover, a one-to-one comparison between the redshifts, ages, metallicities, and stellar masses derived spectroscopically for SDSS and by MUFFIT for ALHAMBRA reveals good qualitative agreements in all the parameters. In addition, and using as input the results from photometric-redshift codes, MUFFIT improves the photometric-redshift accuracy by $\sim 10$-$20\%$, and it also detects nebular emissions in galaxies, providing physical information about their strengths. Our results show the potential of multi-filter galaxy data to conduct reliable stellar population studies with the appropiate analysis techniques, as MUFFIT.Comment: 31 pages, 18 figures, accepted for publication in A&