La Formation du Grand Essert (Jura franco-suisse; Valanginien supérieur p.p. à Hauterivien supérieur basal)

Le terme de Formation du Grand Essert a été proposé en 2016 pour remplacer ceux de « Marnes d’Hauterive » auct. et « Pierre jaune de Neuchâtel » auct. attribués à l’« Hauterivien » auct. dans le Jura franco-suisse. L’objet de cette note est, dans un premier temps, de décrire et d’interpréter la lithologie de la coupe-type représentative de cette nouvelle formation, d’une épaisseur de 112,5 m, relevée dans la localité-type du Grand Essert le long de la route D991, entre Confort et Chésery, sur la rive gauche de la vallée de la Valserine (Jura méridional, Ain, France). La Formation du Grand Essert comprend, à la base, le Membre d’Hauterive composé de 52 m de marnes dans lesquelles apparaissent des bancs et des nodules calcaires contenant souvent des grains de quartz et de glauconie. Les faciès indiquent un milieu calme en dessous de la limite de l’action des vagues de beau temps, avec l’apport périodique de matériel bioclastique allochtone. Au-dessus, le Membre de Neuchâtel d’une épaisseur de 60,5 m se compose de calcaires bioclastiques localement quartzo-glauconieux. Au sein de ce membre s’intercale un horizon marneux d’origine marine, les Marnes des Uttins. Les bancs calcaires montrent des structures sédimentaires entrecroisées qui suggèrent la présence de courants tidaux. Dans un deuxième temps, les auteurs proposent des corrélations basées sur la biostratigraphie (ammonites et dinokystes) et l’analyse séquentielle, entre la coupe-type et d’autres coupes et forages publiés dans le Jura franco-suisse. La corrélation avec une coupe du Bassin vocontien (Haut Vergons) permet de discuter jusqu’à quel point l’enregistrement sédimentaire de la Formation du Grand Essert était contrôlé par des fluctuations du niveau marin. Finalement, les ammonites et dinokystes permettent de bien dater la Formation du Grand Essert qui s’étend du Valanginien supérieur pro parte jusqu’à la base de l’Hauterivien supérieur. Le Membre d’Hauterive commence dans la zone à Peregrinus. L’intervalle Peregrinus-Furcillata est partout fortement condensé (comme la partie sommitale de la Formation du Vuache sous-jacente dans le Jura neuchâtelois) tandis que les sédiments de la zone à Radiatus sont bien représentés. La limite entre le Membre d’Hauterive et le Membre de Neuchâtel se situe dans la zone à Loryi. Le Membre de Neuchâtel occupe la partie supérieure de la zone à Loryi et toute la zone à Nodosoplicatum. La limite Nodosoplicatum / Sayni se trouve au sein de la partie sommitale du Membre de Neuchâtel. La base de la Formation des Gorges de l’Orbe sus-jacente est datée de la zone à Sayni

Aging of large area CsI photocathodes for the ALICE HMPID prototypes

The ALICE HMPID RICH detector is equipped with CsI photocathodes in a MWPC for the detection of Cherenkov photons. The long term operational experience with large area CsI photocathodes will be described. The RICH prototypes have shown a very high stability of operation and performance, at a gain of 10 \5 and with rates up to 2x10 \4 cm-2 s-1. When exposure to air has been avoided, no degradation of the CsI quantum efficiency has been observed on photocathodes periodically exposed to test-beams over 7 years, corresponding to local integrated charge densities of ~ 1 mC cm-2. The results of limited exposures to oxygen and humidity will also be presented

A threshold imaging Cerenkov detector with CsI photocathodes

A Threshold Imaging Cherenkov (TIC) detector, in conjunction with a tracking device and a time-of-flight system, has been developed to allow pion, kaon and proton identification in the 3--8 GeV/$c$ range of momenta. The system allows spatial identification of the photons of particles above the Cherenkov threshold and their correlation to a particular track. The TIC detector uses a MWPC detector with a CsI coated photocathode for photon conversion. The results obtained in ultrarelativistic lead--lead collisions at the CERN SPS accelerator are presented

Final tests of the CsI-based ring imaging detector for the ALICE experiment

We report on the final tests performed on a CsI-based RICH detector equipped with 2 C$_6$F$_{14}$ radiator trays and 4 photocathodes, each of 64$\times$38 cm$^2$ area. The overall performance of the detector is described, using different gas mixtures, in view of optimizing the photoelectron yield and the pad occupancy. Test results under magnetic field up to 0.9 T, photocathode homogeneity and stability are presented

The Present Development of CsI Rich Detectors for the ALICE Experiment at CERN

The ALICE Collaboration plans to implement a 12m^2 array consisting of 7 proximity focussed C6F^14 liquid radiator RICH modules devoted to the particle identification in the momentum range: 1 GeV/c - 3.5 GeV/c for pions and kaons. A large area CSI-RICH prototype has been designed and built with the aim to validate the detector parameter assumptions made to predict the performance of the High Momentum Particle Identification System (HMPID) of the ALICE Experiment. The main elements of the prototype will be described with emphasis on the engineering solutions adopted. First results from the analysis of multitrack events recorded with this prototype exposed to hadron beams at the CERN SPS will be discussedList of FiguresFigure 1 General view of the ALICE lay-outFigure 2 Schematic layout of the fast CsI-RICHFigure 3 Perspective view of the HMPID layout with the seven RICH modules tilted according to their position with respect to the interaction vertex. The frame that supports the detectors is also shownFigure 4 Top view of the photodetector anode plane with the wire support spacer. One CsI board, out of six forming the pad cathode plane, is also shown.Figure 5 Perspective view of the HMPID honeycomb panel with the three radiator vesselsFigure 6 Cut away view of the HMPID CsI-RICH showing separately each detector component. Kapton buses that carry signals from the pads to the readout electronics are also shownFigure 7 a)number of resolved photoelectrons per event, b)reconstructed Cherenkov angle per photonFigure 8 C6F14 transmission plots before and after the molecular sieve purificationFigure 9 Display plot showing an SPS event. Three tracks are reconstructed by using the tracking chamber telescope, the associated rings are shown in the HMPID prototypeThis publication also appears as INT-98-20

A progress report on the development of the CsI-RICH detector for the ALICE experiment at LHC

The particle identification in ALICE (A Large Ion Collider Experiment) at LHC will be achieved by two complementary systems based on time of flight measurement, at low $p_t$, and on the Ring Imaging Cherenkov (RICH) technique, at $p_t$ ranging from 2 to 5 GeV/$c$, respectively. The High Momentum PID (HMPID) system will cover $\sim$5\% of the phase space, the single arm detector array beeing composed by seven 1.3$\times$1.3 m$^2$ CsI-RICH modules placed at 4.7 m from the interaction point where a density of about 50 particles/m$^2$ is expected.\\ A 1 m$^2$ prototype, 2/3 of HMPID module size, has been successfully tested at the CERN/PS beam where 18 photoelectrons per event have been obtained with 3 GeV/c pions and 10 mm liquid $\mathrm{C}_6\mathrm{F}_{14}$ radiator. Mechanical problems related to the liquid radiator vessel construction have been solved and the prototype, fully equipped, will be tested at the CERN/SPS to investigate the PID capability in high particle density events.\\ In this report, after an introductory discussion on the requirements for PID in ALICE, the HMPID prototype is described and the main results of beam tests on large area CsI photocathodes, operated in RICH detectors, are given

The STAR-RICH Detector

The STAR-RICH detector extends the particle idenfication capabilities of the STAR spectrometer for charged hadrons at mid-rapidity. It allows identification of pions and kaons up to ~3 GeV/c and protons up to ~5 GeV/c. The characteristics and performance of the device in the inaugural RHIC run are described

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

Micropaléontologie d'une plate-forme bioclastique échinodermique : les calcaires à entroques du Bajocien du Jura méridional et de Bourgogne

Les microfaunes des plates-formes bioclastiques échinodermiques, très méconnues, sont illustrées par l'étude du Bajocien du Jura méridional, de Bourgogne et des Chaînes subalpines. Les faciès essentiellement calcaires (travail en section), font l'objet d'un inventaire exhaustif de la microfaune qui, est regroupée en 3 associations (AF1-AF3). AF1 (spicules, foraminifères monocristallins, pelagos, etc.) est abondant principalement dans les boues à madréporaires, AF2 (foraminifères porcelanés, péloïdes, petits agglutinés, etc.) dans les alternances marno-calcaires, et AF3 dans les faciès bioclastiques (crinoïdes, bryozoaires, fragments coquillés, etc.). Leur évolution le long des coupes permet de proposer une interprétation séquentielle (6 séquences de dépôt) et un modèle paléoécologique nouveau. La sédimentation oscille entre 2 pôles principaux. 1) Episodes à polypiers et calcaires oolithiques correspondent à des périodes à climat chaud et aride (eaux chaudes, claires, oligo-mésotrophiques). 2) Calcaires bioclastiques à entroques correspondent à des périodes à climat plus humide (eaux à tendance eutrophiques)