Muon tomography applied to active volcanoes

Muon tomography is a generic imaging method using the differential absorption of cosmic muons by matter. The measured contrast in the muons flux reflects the matter density contrast as it does in conventional medical imaging. The applications to volcanology present may advantadges induced by the features of the target itself: limited access to dangerous zones, impossible use of standard boreholes information, harsh environmental conditions etc. The Diaphane project is one of the largest and leading collaboration in the field and the present article summarizes recent results collected on the Lesser Antilles, with a special emphasis on the Soufri\`ere of Guadeloupe.Comment: 7 pages, 7 figures, International Conference on New Photo-detectors,PhotoDet2015, 6-9 July 2015, Moscow, Troitsk, Russia. Submitted to Po

Design and operation of a field telescope for cosmic ray geophysical tomography

International audienceThe cosmic ray muon tomography gives an access to the density structure of geological targets. In the present article we describe a muon telescope adapted to harsh environmental conditions. In particular the design optimizes the total weight and power consumption to ease the deployment and increase the autonomy of the detector. The muon telescopes consist of at least two scintillator detection matrices readout by photosensors via optical fibres. Two photosensor options have been studied. The baseline option foresees one multianode photomultiplier (MAPM) per matrix. A second option using one multipixel photon counter (MPPC) per bar is under development. The readout electronics and data acquisition system developed for both options are detailed. We present a first data set acquired in open-sky conditions compared with the muon flux detected across geological objects

Acoustic Emissions in Granular Structures under Gravitational Destabilization

International audienceIn this work, we perform experiments in an acoustic tank to record acoustic emissions (A Es) occurring when a granular medium is submitted to a gravitational destabilization. The granular medium is composed ofmonodisperse glass beads filling a box which can be inclined From a =O° up to the avalanche threshold angle ao=28 °. To respect quasi-static conditions, the angle increases by steps less than 3°/mn. An omnidirectional hydrophone records the continuous acoustic field in the bead structure until the avalanche occurs. We compare the results for different experimental configurations, in particular for dry and water saturated granular media, but also for different bead diameters (d=8, 3 and 0.3 mm) in order to span the viscosity range of the granular structure. We show that the AE signatures strongly depend on the viscosity parameter, which can be related to the Stokes number and the fluid/solid density ratio. The transition From a viscous to an inertial dynamic of the granular structure is discussed, based on these experimental results

Imagerie de l'EDZ dans la galerie 04 du laboratoire souterrain du Mont Terri par endoscopie sismique

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Seismic endoscopy and tomography of the EDZ of the Gallery 04 in the Mont Terri rock laboratory

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Planning and Tracking Chemotherapy Production for Cancer Treatment: a Performing and Integrated Solution

International audiencePurpose: Chemotherapy drugs are intended for the treatment of cancer. The production of such drugs and their administration to the patient is a delicate and expensive operation. The study deals with the acquisition and processing of data regarding the production of intravenous chemotherapy, from the production request (the medical prescription), the production itself (pharmaceutical process), to the delivery in the health care unit, for the administration of the chemotherapy. The goal of this study is to develop a system that can schedule, control and track the chemotherapy preparations and satisfy a certification process of quality management ("ISO 9001 version 2000" standard). Methods: The solution proposed in this paper was developed within the framework of a common certification process at the Biopharmaceutical Unit of the Oncology Clinic (UBCO) of the Bretonneau hospital in Tours (France). The system consists of two software programs: a software to insure traceability and a decision making software to plan the production. To simplify the data entry process, some mobile entry points with bar code reader have been deployed. These tools enable an accurate tracking of the production, a security and control for the schedule production phases, and a full traceability of each operation leading to the administration of the chemotherapy drug. Results: The first result is a software that creates the production schedule, allows a real time control of the production process and a full traceability of each step. Computational experiments are based on real data sets, with a comparison of a time period before and after the implementation of this solution. The results show the positive impacts of this software, like the reduction of delayed deliveries, real time generation of production indicators, optimization of the production and a saving of staff time. Conclusions: This intuitive system guarantees a traceability in connection with a high quality system certified ISO 9001-v2000 (with a rapid data entry), an assistant to schedule the production of preparations in a better way, a permanent follow-up and analysis of operations. This project proves the benefits of implementing computer solutions for the traceability and assistance in decision making in the hospital systems

Electrical tomography monitoring of the EDZ during the excavation of the Gallery 04 in the Mont Terri rock laboratory

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Underground Traffic‐Induced Body Waves Used to Quantify Seismic Attenuation Properties of a Bimaterial Interface Nearby a Main Fault

International audienceUnderground traffic activities spread ground-borne vibrations in a complex way. The present work focuses on 173 individual vehicles tracked as moving sources of vibrations in the Mont Terri rock laboratory, located 95m away from a motorway tunnel. Two neighboring geophones record the vertical ground velocity of traffic-induced events with peak particle velocities ranging in 0.15–0.35 m/s. A dynamic cross-correlation of the waveforms is used to align the individual events for coherent and robust analysis. A root mean square (rms) method allows identifying the main feature, centered at the Main Fault, and an unexpected feature located about 140m apart. The dominant seismic frequencies are 15 and 10Hz, respectively. The vehicle speeds (70–90km/h), estimated from the time-delay between the two features, and the seismic velocity (800–2,300m/s), assessed from a simple kinematic model, are used to convert time to position along the tunnel, allowing modeling the local rms with the Bornitz's equation. The resolved frequency-independent attenuation coefficients are 2.61s/km in the Opalinus Clay including the gallery network, and 1.23s/km in the Limestone, a contrast of elastic properties that defines a bimaterial interface. A particle motion analysis highlights body waves, with dominant vertically polarized shear waves above the Main Fault. The origin of the unexpected feature is discussed in terms of site effects and seismic propagation in a heterogeneous fracture network. Traffic-induced events can be used as reproducible, low-frequency, and non-destructive sources with potential interest in long-term monitoring at the scale of an underground gallery

Muon tomography and Volcanic Risks in the Lesser Antilles: the Example of the Soufrière of Guadeloupe

International audienceThe Lesser Antilles is a subduction volcanic arc counting a dozen of either potentially or presently eruptingvolcanoes located in populated areas. During the last century violent eruptions occurred, killing 29000 people in1902 with the explosion of La Montagne Pelée in Martinique, leading to the evacuation of 73000 persons during 6months during the 1976 crisis of La Soufrière of Guadeloupe, and devastating most of the Montserrat island sincethe beginning in 1995 of the yet ongoing eruption of the Soufrière Hills.The Soufrière of Guadeloupe volcano is subjected to an intense hydrothermal activity which alters the mechanicalintegrity of the lava dome with a high risk level of destabilisation. Indeed, 8 flank collapses occurred during thelast 8500 years, several of them were followed by the creation of new lava domes. The present dome is dated1530 B.P. And appears very heterogeneous as revealed by both seismic tomography and electrical resistivitytomography. Gravity data show that the bulk density of the dome is about 2.2 g/cm3. The hydrothermal activityat the summit of the Guadeloupe Soufrière is regularly increasing with emitted fluids becoming more and moreacid. Imaging the internal structure of such a volcano brings important informations for the hazard evaluation anddensity muon tomography is particularly adapted to brought constraints on collapse models.A muon telescope was placed at the base of the lava dome the Guadeloupe Soufrière in July 2010. This fieldinstruments is adapted to the extreme field conditions encountered during hurricane season and it is entirelyautonomous with a total power consumption of less than 40W. Ethernet link allows both daily downloading ofthe data and remote control of the electronic devices and on-board computers. The telescope is equipped with3 scintillator matrices completed with an iron shielding of 24 mm in thickness in order to efficiently filter outfortuitous events. The density radiographies obtained with this telescope are presented and compared with theother geophysical data available on this volcano

Geophysical monitoring of the EDZ during a gallery excavation in the Opalinus Clay of the Mont Terri URL: design and principles of specific in situ experimental setups

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