IDeF-X ASIC for Cd(Zn)Te spectro-imaging systems

Joint progresses in Cd(Zn)Te detectors, microelectronics and interconnection technologies open the way for a new generation of instruments for physics and astrophysics applications in the energy range from 1 to 1000 keV. Even working between -20 and 20 degrees Celsius, these instruments will offer high spatial resolution (pixel size ranging from 300 x 300 square micrometers to few square millimeters), high spectral response and high detection efficiency. To reach these goals, reliable, highly integrated, low noise and low power consumption electronics is mandatory. Our group is currently developing a new ASIC detector front-end named IDeF-X, for modular spectro-imaging system based on the use of Cd(Zn)Te detectors. We present here the first version of IDeF-X which consists in a set of ten low noise charge sensitive preamplifiers (CSA). It has been processed with the standard AMS 0.35 micrometer CMOS technology. The CSA are designed to be DC coupled to detectors having a low dark current at room temperature. The various preamps implemented are optimized for detector capacitances ranging from 0.5 up to 30 pF.Comment: 8 pages, 11 figures, IEEE NSS-MIC conference in Rome 2004, submitted to IEEE TNS, correction in unit of figure

Amateurisme et expertise, convergence des buts

Depuis 2011, la compagnie Gongle conçoit des performances artistiques et sportives avec des acteurs du champ footballistique. Cette collaboration entre experts issus de disciplines qui s’ignorent subvertit les critères de justesse et valorise des cultures et des modes d’expression minorés par l’institution théâtrale. Ici, professionnalisme et excellence apparaissent comme des valeurs secondaires au regard des finalités qui sont assignées à la représentation théâtrale.Since 2011, the Gongle Theatre Company has been creating artistic and sports performances with actors involved in the field of football. This collaboration between experts from domains that usually overlook one another subverts the criteria of rightness whilstvaluing cultures and forms of expression underestimated by the theatrical institution. Here, professionalism and the notion of excellence appear as secondary values regarding the purposes that are ascribed to theatrical representation

CEA Bolometer Arrays: the First Year in Space

The CEA/LETI and CEA/SAp started the development of far-infrared filled bolometer arrays for space applications over a decade ago. The unique design of these detectors makes possible the assembling of large focal planes comprising thousands of bolometers running at 300 mK with very low power dissipation. Ten arrays of 16x16 pixels were thoroughly tested on the ground, and integrated in the Herschel/PACS instrument before launch in May 2009. These detectors have been successfully commissioned and are now operating in their nominal environment at the second Lagrangian point of the Earth-Sun system. In this paper we briefly explain the functioning of CEA bolometer arrays, and we present the properties of the detectors focusing on their noise characteristics, the effect of cosmic rays on the signal, the repeatability of the measurements, and the stability of the system

Impacts of The Radiation Environment At L2 On Bolometers Onboard The Herschel Space Observatory

We present the effects of cosmic rays on the detectors onboard the Herschel satellite. We describe in particular the glitches observed on the two types of cryogenic far- infrared bolometer inside the two instruments PACS and SPIRE. The glitch rates are also reported since the launch together with the SREM radiation monitors aboard Herschel and Planck spacecrafts. Both have been injected around the Lagrangian point L2 on May 2009. This allows probing the radiation environment around this orbit. The impacts on the observation are finally summarized.Comment: 8 pages, 13 figures, 2 images, Author Keywords: Bolometers, Infrared detectors, cryogenics, radiation effects, submillimeter wave technology IEEE Terms: Bolometers, Detectors, Instruments, Picture archiving and communication systems, Protons, Silicon, Space vehicles; Radiation and Its Effects on Components and Systems (RADECS), 2011 12th European Conference. Conference location: Sevilla. Date of Conference: 19-23 Sept. 2011. Session H: Radiation Environment: Space, Atmospheric and Terrestrial (PH2

Variabilités spatiales et temporelles de la qualité physico-chimique et des invertébrés pélagiques des eaux de la retenue hydroélectrique de Petit Saut (Guyane française).

Le bassin versant du fleuve Sinnamary est situé en Guyane française, au nord du continent sud américain, en zone néo-tropicale. Il s'étend entre 4 et 5°de latitude Nord et entre 52°50' et 53°30' de longitude Ouest. En 1994, la mise en eau du barrage hydroélectrique construit sur le site de Petit Saut occasionne l'ennoiement de 365 km2 de forêt primaire. Le remplissage s'effectue en 18 mois, et la demande en oxygène dissous nécessaire à la dégradation de la matière organique est telle qu'en quelques jours la masse d'eau se stratifie en un épilimnion oxygéné et un hypolimnion anoxique. Représentant quelques centimètres en 1994, l'épilimnion s'épaissit progressivement jusqu'en 1998. Depuis, cette progression s'est nettement ralentie et l'épilimnion oscille autour d'une valeur moyenne de 5 à 6 mètres. Il abrite la plus grande partie du zooplancton pélagique. L'hypolimnion est anoxique et riche en éléments réduits. Le zooplancton s'est rapidement installé avec des rotifères, des cladocères et des copépodes. Des ostracodes et des Chaoboridae y sont désormais associés. La retenue présente une zonation longitudinale, de la tête de la retenue vers la queue, aussi bien en termes de densités que de composition des peuplements. De même, il existe une zonation transversale, notamment marquée par un gradient croissant de la conductivité de l'axe vers les berges. Ces ressources endogènes ainsi que des apports complémentaires (végétaux, invertébrés terrestres, détritus…) sont utilisées par la faune ichtyque qui a su s'adapter au changement du milieu. Le temps de rétention des eaux qui fluctue saisonnièrement en fonction des pluies semble être le facteur prépondérant de variabilité pour la qualité physico-chimique des eaux et les communautés biologiques.The Sinnamary River is located in a neotropical zone, in French Guiana, in the northern part of South America. Its flood basin extends between 4° and 5° N latitude and 52°50' and 53°30' W longitude. The river is found in an equatorial climate, and is influenced by its proximity to the ocean. The temperature varies little, with an average of 25°C for the least hot month (January) and 27°C for the hottest month (October). The humidity is always high and averages more than 90%. The Sinnamary River bed is broad (> 50 m), and runs from south to north for approximately 240 km with a very weak slope (0.0003%). Petit Saut, the site of the hydroelectric dam, is located approximately 60 km from the mouth of the river, with a flood basin area of 5927 km2 and an average flow rate 260 m3 /s.The construction of the hydroelectric dam at Petit Saut in 1994 resulted in the flooding of 365 km2 of primary forest in a neotropical zone (the average depth of the reservoir is 11 m). The dam reservoir was filled over a period of 18 months and the amount of dissolved oxygen necessary for the organic matter to decompose was such that, in a matter of days, the body of water became stratified into an oxygenated epilimnion and an anoxic hypolimnion. Only centimeters thick in 1994, by 1998 the epilimnion had progressively expanded. Since that time it has varied between an average thickness of 5 to 6 m and is home to various biological communities. The hypolimnion is anoxic and rich in reduced compounds (nitrogen and phosphorus minerals, dissolved organic matter, particles, metals and gas). The products of the degradation of the flooded organic matter, which still prevail at the bottom, are gradually relayed towards surface by phenomena of dilution, hydrolysis and oxidation.The river fauna disappeared from the reservoir and was replaced after a few weeks by various pelagic fauna. The zooplanktonic communities, primarily confined to the epilimnion, were quickly settled with rotifera, cladocera and copepoda. Initially dominated by detritivores (Bosminidae) and Cyclopidae from February to May 1994, the settlements diversified with phytophagous zooplankton (Calanidae and Daphniidae) when the phytoplankton developed. This procession was quickly accompanied by Sididae, which has dominated the cladocera since mid-1996 and by ostracoda, which were particularly abundant from 1995 to 1997. Carnivores such as Chaoboridae larvae were also present in Petit Saut reservoir. In contrast to the other zooplankton species, Chaoboridae larvae occupy the entire water column. As a result of great quantities of organic matter available at the time the reservoir was filled, the biomasses were initially large and have gradually decreased with decreasing nutrient concentrations.The reservoir was not homogeneous in terms of zooplankton density, with a longitudinal zonation from the dam towards the upstream tail. In the tail, fauna were identical to those of the river. In the lake zone, phytophagous Calanidae dominated. In the intermediate zone, known as the zone of transition, the zooplankton biomass normalized to the volume of oxygenated water was less important than in the lake zone. Cyclopidae, well represented at the time of the reservoir colonization, dominated the communities in the transition zone. This distribution of zooplankton was likely connected with the dissolved oxygen concentrations, as well as with the quantities of phytoplankton and bacterio-chlorophyll. Similarly, there was a transverse zonation, marked by an increase in conductivity towards the reservoir banks. The density of the communities varied seasonally. The highest biomasses were measured along the central axis at the time of high waters and close to the banks at the time of low waters.The time of water retention, which fluctuates according to the rainy season, seemed to be the factor dominating the physicochemical water quality variability and the biological communities. The rainy season is characterized by the dilution of various elements (e.g., conductivity is reduced). Conversely, during the dry season, the elements concentrate again in the water mass. Nevertheless, the peaks of pelagic invertebrate density were observed during times of high waters, when the hydraulic conditions favour the exchanges between the hypolimnion (anoxic and rich in nutritive elements) and the epilimnion (oxygenated and very low in nutrients).These endogenous resources, as well as complementary contributions (vegetation, invertebrate, terrestrial, refuse), are used by the fish fauna, which adapted to the change in their environment. Predation contributes to the seasonal evolution of the zooplankton. Predation pressure was more important in the dry season than in the rainy season

Simulations of Galactic Cosmic Ray Impacts on the Herschel/PACS bolometer Arrays with Geant4 Code

The effects of the in-flight behaviour of the bolometer arrays of the Herschel/PACS instrument under impacts of Galactic cosmic rays are explored. This instrument is part of the ESA-Herschel payload, which will be launched at the end of 2008 and will operate at the Lagrangian L2 point of the Sun-Earth system. We find that the components external to the detectors (the spacecraft, the cryostat, the PACS box, collectively referred to as the `shield') are the major source of secondary events affecting the detector behaviour. The impacts deposit energy on the bolometer chips and influence the behaviour of nearby pixels. 25% of hits affect the adjacent pixels. The energy deposited raises the bolometer temperature by a factor ranging from 1 to 6 percent of the nominal value. We discuss the effects on the observations and compare simulations with laboratory tests.Comment: Experimental Astronomy, 2008, in pres

A study on the use of the PACS bolometer arrays for submillimeter ground-based telescopes

A new kind of bolometric architecture has been successfully developed for the PACS photometer onboard the Herschel submillimeter observatory. These new generation CCD-like arrays are buttable and enable the conception of large fully sampled focal planes. We present a feasibility study of the adaptation of these bolometer arrays to ground-based submillimeter telescopes. We have developed an electro-thermal numerical model to simulate the performances of the bolometers under specific ground-based conditions (different wavelengths and background powers for example). This simulation permits to determine the optimal parameters for each condition and shows that the bolometers can be background limited in each transmission window between 200 and 450 microns. We also present a new optical system that enables to have a maximum absorption of the bolometer in each atmospheric windows. The description of this system and measurements are showed.Comment: 9 pages, 12 figures, to be published in the Proceedings of SPIE Vol. 6275, "Astronomical Telescopes and Instrumentation, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III

Influence de la pluviométrie et de la mise en place du barrage de Petit Saut (Guyane française) sur la répartition des lépidoptères Sphingidae

The family Sphingidae bas an important potential as bio-indicators given the 118 species so far enumerated in French Guiana. For instance, more than 25,000 individuals from 104 species have been captured during 90 monthly censuses between January 1990 and October 1997 in the region of Petit Saut, a low-altitude primary forest. Among these species, seven are considered as uncommon on the site of Petit Saut. Therefore, ca 50 % of the species with a sufficient number of individuals for the analysis (n = 30) display particular characteristics: the probability of occurrence differs significantly between months for 14.5 % of them, and for the majority of the species of this farnily seasonal variations in populations abundances are not linked to rainfall, which is usually the most important ecological factor in this environment, temperature being constant in Guianan forest. These fluctuations are therefore due to other factors. The filling of the dam reservoir affected about a third of the species. Adaptations to variations in environmental conditions are not identical across all species . Certain species were not affected by environmental modifications while others grew up taking advantage of these changes and colonized new biotopes, and others decreased.La famille des Sphingidés a des capacités bio-indicatrices très performantes compte tenu des 118 espèces connues en Guyane française. Par exemple, plus de 25 000 individus appartenant à 104 espèces ont été capturés lors des 90 piégeages mensuels effectués entre janvier 1990 et octobre 1997 dans une zone de forêt primaire de basse altitude dans la région de Petit Saut. Parmi ces espèces, sept peuvent être considérées comme rares sur le site du barrage de Petit Saut. Par ailleurs, près de la moitié des espèces ayant un nombre suffisant d'individus pour les analyses (n = 30), présentent un comportement particulier : 14,5 % ont une probabilité d'apparition différente d'un mois à l'autre et pour la plupart des espèces de cette famille, les variations saisonnières observées dans les effectifs ne sont pas liées à la pluviométrie qui est le facteur prépondérant de cet environnement, la température restant constante tout au long de l'année en forêt guyanaise. D'autres facteurs sont à l'origine de cette fluctuation. On peut observer que, selon les espèces, les adaptations aux variations des conditions environnementales ne sont pas identiques. En effet, de nombreuses espèces ne sont pas influencées par ces modifications du milieu tandis que près d'un tiers des espèces sont affectées dans leur apparition par la mise en eau du barrage de Petit Saut. Certaines espèces se sont développées en mettant à profit ces changements et en colonisant de nouveaux biotopes, d'autres voyant leurs effectifs diminue

Hard X-ray polarimetry with Caliste, a high performance CdTe based imaging spectrometer

Since the initial exploration of soft gamma-ray sky in the 60's, high-energy celestial sources have been mainly characterized through imaging, spectroscopy and timing analysis. Despite tremendous progress in the field, the radiation mechanisms at work in sources such as neutrons stars and black holes are still unclear. The polarization state of the radiation is an observational parameter which brings key additional information about the physical process. This is why most of the projects for the next generation of space missions covering the tens of keV to the MeV region require a polarization measurement capability. A key element enabling this capability is a detector system allowing the identification and characterization of Compton interactions as they are the main process at play. The hard X-ray imaging spectrometer module, developed in CEA with the generic name of Caliste module, is such a detector. In this paper, we present experimental results for two types of Caliste-256 modules, one based on a CdTe crystal, the other one on a CdZnTe crystal, which have been exposed to linearly polarized beams at the European Synchrotron Radiation Facility. These results, obtained at 200-300 keV, demonstrate their capability to give an accurate determination of the polarization parameters (polarization angle and fraction) of the incoming beam. Applying a selection to our data set, equivalent to select 90 degrees Compton scattered interactions in the detector plane, we find a modulation factor Q of 0.78. The polarization angle and fraction are derived with accuracies of approximately 1 degree and 5%. The modulation factor remains larger than 0.4 when essentially no selection is made at all on the data. These results prove that the Caliste-256 modules have performances allowing them to be excellent candidates as detectors with polarimetric capabilities, in particular for future space missions.Comment: 17 pages, 14 figures, 2 tables in Experimental Astronomy, 201

Splenic infarction in a patient with autoimmune hemolytic anemia and protein C deficiency

Splenic infarction is most commonly caused by cardiovascular thromboembolism; however, splenic infarction can also occur in hematologic diseases, including sickle cell disease, hereditary spherocytosis, chronic myeloproliferative disease, leukemia, and lymphoma. Although 10% of splenic infarction is caused by hematologic diseases, it seldom accompanies autoimmune hemolytic anemia (AIHA). We report a case of a 47-year-old woman with iron deficiency anemia who presented with pain in the left upper abdominal quadrant, and was diagnosed with AIHA and splenic infarction. Protein C activity and antigen decreased to 44.0% (60-140%) and 42.0% (65-140%), respectively. Laboratory testing confirmed no clinical cause for protein C deficiency, such as disseminated intravascular coagulation, sepsis, hepatic dysfunction, or acute respiratory distress syndrome. Protein C deficiency with splenic infarction has been reported in patients with viral infection, hereditary spherocytosis, and leukemia. This is a rare case of splenic infarction and transient protein C deficiency in a patient with AIHA