Monitoring temporal opacity fluctuations of large structures with muon tomography : a calibration experiment using a water tower tank

Usage of secondary cosmic muons to image the geological structures density distribution significantly developed during the past ten years. Recent applications demonstrate the method interest to monitor magma ascent and volcanic gas movements inside volcanoes. Muon radiography could be used to monitor density variations in aquifers and the critical zone in the near surface. However, the time resolution achievable by muon radiography monitoring remains poorly studied. It is biased by fluctuation sources exterior to the target, and statistically affected by the limited number of particles detected during the experiment. The present study documents these two issues within a simple and well constrained experimental context: a water tower. We use the data to discuss the influence of atmospheric variability that perturbs the signal, and propose correction formulas to extract the muon flux variations related to the water level changes. Statistical developments establish the feasibility domain of muon radiography monitoring as a function of target thickness (i.e. opacity). Objects with a thickness comprised between $\simeq$ 50 $\pm$ 30m water equivalent correspond to the best time resolution. Thinner objects have a degraded time resolution that strongly depends on the zenith angle, whereas thicker objects (like volcanoes) time resolution does not.Comment: 11 pages, 9 figures. Final version published in Scientific Reports, Nature, 14 march 201

Preliminary Irradiation Tests Of The Apvd Circuit For The

The APVD circuit, developed in the 0.8 radiation hard SOI DMILL technology [2][3][4] from ATMEL/TEMIC-MHS Nantes, for the front end electronic of the CMS tracker, has been irradiated at CERN using a 10KeV Xray beam up to a total dose of 20Mrad. The main performances of the APVD like gain, pulse shape, noise are presented as a function of the radiation dose. In particular the cause of the DAC non linearity in the bias generator part is discussed

Reconstruction of Tertiary palaeovalleys in the South Alpine Foreland Basin of France (Eocene-Oligocene of the Castellane arc)

International audienceThe dynamics of depositional environments and the spatial deformation of drainage networks in foreland basins reflect the tectonic and erosional dynamics associated with the development of mountain belts. The spatial and temporal organization of the Eocene-Oligocene (40-25 Ma) sedimentation in the external part of the South Alpine Foreland Basin of France was reconstructed using an integrated cartographic, sedimentological and petrographic analysis of the Tertiary sedimentary successions. The depositional geometries and variations in facies and thickness of the Palaeogene Nummulitic succession, as well as the observed flow directions in various continental and marine sediments, suggest that the Barreme, Blieux and Taulanne synclines were present as palaeovalleys since the Eocene. The sedimentological analysis of the Nummulitic succession allows the identification of three depositional sequences separated by transgressive surfaces that are recognized in the Barreme, Blieux and Taulanne synclines. Correlation of these sequences between the three synclines suggests that these palaeovalleys were connected by a local valley network that recorded the same sea-level fluctuations during the marine Nummulitic sedimentation. The palaeovalley network was structurally controlled by the east-west axes of the Blieux and Taulanne synclines and the north-south axis of the Barreme syncline formed during the "Pyrenean-Provencal" (Late Cretaceous-Middle Eocene) shortening and the first stage of the Alpine history (Middle Eocene) respectively. Later on, the westward "Alpine" compression (since the Early Oligocene) induced local depocenter migration and reversal in flow direction. However, compared to the modern river pattern, the palaeovalley orientation highlights a geometrical stability since their formation (about 40 Ma), suggesting a long-term stability of the early structures in the foreland basin. This constancy can be explained by the location of the study area in a piggy-back basin transported at the top of the Provencal thrust sheet that facilitated the preservation of the overall axis orientation of the palaeovalleys

Radiographier lesvolcans avec des rayons cosmiques : instrumentationet applications

National audienceLes muons d’origine cosmique sont des particules éphémères de hauteénergie pouvant traverser plusieurs kilomètres de roche. Le principede la radiographie par muons consiste à déterminer la densité d’unmassif rocheux en mesurant l’atténuation qu’il produit sur le flux demuons. Les principes physiques et les difficultés de cette nouvelle méthoded’imagerie seront décrites ainsi que les télescopes de terrain quenous avons conçus et réalisés. Les performances de la méthodes serontillustrés à l’aide des résultats d’expériences réalisées sur des volcans(Soufrière de Guadeloupe, Etna, Mayon) et en laboratoire souterrain(Mont Terri)

Oxygen isotope fractionation between apatite-bound carbonate and water determined from controlled experiments with synthetic apatites precipitated at 10–37 °C

The oxygen isotope fractionation between the structural carbonate of inorganically precipitated hydroxyapatite (HAP) and water was determined in the range 10–37 °C. Values of 1000 ln α(CO32- –H2O) are linearly correlated with inverse temperature (K) according to the following equation: 1000 ln α(CO32- –H2O) = 25.19 (±0.53)-T-1 - 56.47 (±1.81) (R2 = 0.998). This fractionation equation has a slightly steeper slope than those already established between calcite and water (O'Neil et al., 1969; Kim and O'Neil, 1997) even though measured fractionations are of comparable amplitude in the temperature range of these experimental studies. It is consequently observed that the oxygen isotope fractionation between apatite carbonate and phosphate increases from about 7.5 pour mille up to 9.1pour mille with decreasing temperature from 37 °C to 10 °C. A compilation of δ18O values of both phosphate and carbonate from modern mammal teeth and bones confirms that both variables are linearly correlated, despite a significant scattering up to 3.5 pour mille, with a slope close to 1 and an intercept corresponding to a 1000 ln α(CO32- –PO43-) value of 8.1 pour mille. This apparent fractionation factor is slightly higher or close to the fractionation factor expected to be in the range 7–8 pour mille at the body temperature of mammals