Design, Construction and In Situ Testing of a Muon Camera for Earth Science and Civil Engineering Applications

The MUST2 (MUon Survey Tomography based on Micromegas detectors for Unreachable Sites Technology) camera is based on a thin Time Projection Chamber read by a resistive Micromegas. This innovative combination presents interesting distinctive features compared to existing muon detection technologies. It allows a wide angular acceptance of the detector with a low weight and compact volume, well adapted for confined spaces or underground operation. The current work presents the results obtained during the calibration measurements at the reference site, the Low Background Noise Laboratory (LBNL). Preliminary results from field measurement campaign carried out at the dam overlooking the village of Saint-Saturnin-les-Apt (South-East of France) are presented and discussed

Développement et applications de détecteurs gazeux à micro-pistes pour la tomographie muonique

This thesis describes the first attempts to perform both absorption and scattering muon tomography using high granularity Micromegas detectors. This imaging technique using the free, available and harmless cosmic ray muons radiation shows great possibilities to study various sized objects. In order to make compact and precise portable devices, using one channel of electronics per readout pattern is not possible. To avoid this problem multiplexed detectors have been designed, extensively tested and used in numerous conditions. Latest developments in Micromegas design have been used such as the genetic multiplexing and the 2D strip readout using a resistive layer. The prototypes made were able to achieve a 300µm resolution at the scale of 50cm while using only 61 channels of electronics. Using these detectors, muography data taking campaigns have been performed both in the semi-controlled environment of the Saclay site of CEA and in the wild of the Giza plateau in Egypt. These two campaigns succeeded in imaging the CEA Saclay water tower and the Khufu's pyramid despite the extreme conditions endured by the Micromegas muon telescopes. Large temperature variations of a few tens of Kelvin have been recorded together with a stable operation i.e. an even gain ensuring a steady self triggering system. This stability was achieved using high voltage variations with respect to the environmental conditions. Together with this very first worldwide operation of a Micromegas-based tracker outside a laboratory, scattering muographies have also been done. A small setup imaging handheld objects performed well in separating various materials in time scales of the order of the day while a bigger 1m² setup allowing the scan of a full container was successfully operated. The inversion of the ill-posed problem of the muon scattering was performed using the crude PoCA method and the maximum likelihood one described by Schultz et al.Cette thèse décrit les premiers essais de tomographie muonique par absorption et par déviation en utilisant des détecteurs Micromegas à haute granularité. Cette technique d'imagerie utilisant les rayons cosmiques gratuits, sans dangers et disponibles partout a démontré sa capacité à imager des objets de tailles variées. Afin de construire des outils compacts, précis, et portables, utiliser une voie d'électronique pour lire chaque motif de lecture est impossible. Pour éviter ce problème, des détecteurs multiplexés ont été conçus, testés et mis en situation dans différentes conditions. Il a été tiré parti des dernières améliorations concernant le détecteur Micromegas telles que le multiplexage génétique ou la lecture 2D par pistes sous une couche résistive. Les prototypes qui ont été fabriqués ont atteint une résolution de 300µm sur une surface d'un quart de mètre carré en ne nécessitant que 61 voies d'électronique. Grâce à ces détecteurs, des campagnes de prise de données ont été faites, à la fois dans l'environnement semi-contrôlé du centre CEA de Saclay et sur le plateau de Gizeh en Egypte. Ces deux campagnes ont permis d'imager avec succès le château d'eau du CEA Saclay ainsi que la pyramide de Khéops et ce malgré les conditions extrêmes que les télescopes à muon ont endurées. Des variations de température de plusieurs dizaines de Kelvin ont été enregistrées alors que l'acquisition de données se déroulait de manière stable, c'est-à-dire que les variations du gain n'impactaient pas le système d'auto déclenchement. Cette stabilité a été rendue possible grâce à un ajustement des hautes tensions vis à vis des conditions environnementales. Cela constitue la première mondiale concernant le fonctionnement d'un dispositif de reconstruction de trace à base de Micromégas en extérieur. En parallèle des expériences de muographie par déviation ont été menées. Un dispositif imageant des objets de petite taille est capable de distinguer divers matériaux sur une échelle de temps de l'ordre d'une journée. Une plus grande installation a permis d'imager un conteneur entier. La résolution du problème inverse a été faite en utilisant à la fois l'algorithme simple dit du PoCA ainsi que celui de maximisation de vraisemblance proposé par Schultz et son équipe

Development and applications of micro-pattern gaseous detectors for muon tomography

Cette thèse décrit les premiers essais de tomographie muonique par absorption et par déviation en utilisant des détecteurs Micromegas à haute granularité. Cette technique d'imagerie utilisant les rayons cosmiques gratuits, sans dangers et disponibles partout a démontré sa capacité à imager des objets de tailles variées. Afin de construire des outils compacts, précis, et portables, utiliser une voie d'électronique pour lire chaque motif de lecture est impossible. Pour éviter ce problème, des détecteurs multiplexés ont été conçus, testés et mis en situation dans différentes conditions. Il a été tiré parti des dernières améliorations concernant le détecteur Micromegas telles que le multiplexage génétique ou la lecture 2D par pistes sous une couche résistive. Les prototypes qui ont été fabriqués ont atteint une résolution de 300µm sur une surface d'un quart de mètre carré en ne nécessitant que 61 voies d'électronique. Grâce à ces détecteurs, des campagnes de prise de données ont été faites, à la fois dans l'environnement semi-contrôlé du centre CEA de Saclay et sur le plateau de Gizeh en Egypte. Ces deux campagnes ont permis d'imager avec succès le château d'eau du CEA Saclay ainsi que la pyramide de Khéops et ce malgré les conditions extrêmes que les télescopes à muon ont endurées. Des variations de température de plusieurs dizaines de Kelvin ont été enregistrées alors que l'acquisition de données se déroulait de manière stable, c'est-à-dire que les variations du gain n'impactaient pas le système d'auto déclenchement. Cette stabilité a été rendue possible grâce à un ajustement des hautes tensions vis à vis des conditions environnementales. Cela constitue la première mondiale concernant le fonctionnement d'un dispositif de reconstruction de trace à base de Micromégas en extérieur. En parallèle des expériences de muographie par déviation ont été menées. Un dispositif imageant des objets de petite taille est capable de distinguer divers matériaux sur une échelle de temps de l'ordre d'une journée. Une plus grande installation a permis d'imager un conteneur entier. La résolution du problème inverse a été faite en utilisant à la fois l'algorithme simple dit du PoCA ainsi que celui de maximisation de vraisemblance proposé par Schultz et son équipe.This thesis describes the first attempts to perform both absorption and scattering muon tomography using high granularity Micromegas detectors. This imaging technique using the free, available and harmless cosmic ray muons radiation shows great possibilities to study various sized objects. In order to make compact and precise portable devices, using one channel of electronics per readout pattern is not possible. To avoid this problem multiplexed detectors have been designed, extensively tested and used in numerous conditions. Latest developments in Micromegas design have been used such as the genetic multiplexing and the 2D strip readout using a resistive layer. The prototypes made were able to achieve a 300µm resolution at the scale of 50cm while using only 61 channels of electronics. Using these detectors, muography data taking campaigns have been performed both in the semi-controlled environment of the Saclay site of CEA and in the wild of the Giza plateau in Egypt. These two campaigns succeeded in imaging the CEA Saclay water tower and the Khufu's pyramid despite the extreme conditions endured by the Micromegas muon telescopes. Large temperature variations of a few tens of Kelvin have been recorded together with a stable operation i.e. an even gain ensuring a steady self triggering system. This stability was achieved using high voltage variations with respect to the environmental conditions. Together with this very first worldwide operation of a Micromegas-based tracker outside a laboratory, scattering muographies have also been done. A small setup imaging handheld objects performed well in separating various materials in time scales of the order of the day while a bigger 1m² setup allowing the scan of a full container was successfully operated. The inversion of the ill-posed problem of the muon scattering was performed using the crude PoCA method and the maximum likelihood one described by Schultz et al

Benchmark of multiple geophysics tools to study the voids in the upper levels of a decommissioned iron mine

&amp;lt;p&amp;gt;Absorption muon imaging is a technique that can measure density variations underground down to a few hundred meters. Then, it can prove to be useful in a mining environment: to help assess the ore bodies volumes and/or to monitor the underground for natural hazards that can happen at the surface because of the mining exploitation. Here we report the result of an experiment designed to test the capabilities and resolution power of a cosmic muon measurement in a mining environment compared to other standard geophysics tools: gravimetry and seismic studies. It consists of three independent measurement of a subset of the decommissioned iron mine of May-sur-Orne (France). The first one was made using a 50x50cm&amp;amp;#178; micromegas based muon telescope installed at the deepest non-submerged level (50m underground) during 3 months. The second one is a gravimetry survey of the surface area inside the muon telescope acceptance cone. And the third one is a study of refracted and reflected seismic waves along a single line above the muon telescope location. The investigation volume was chosen because of the presence of surface risks (neighborhood), the unknown of some uncharted volume and the presence of an ore storage volume of several meter cubed that was used during the mine exploitation and which filling state is unknown.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;The data analysis showed that while muon tomography is able to detect the negative density anomaly of the storage volume, the gravimetry measurement is not sensible to it. However, the seismic study was able to detect the volume as well and its location and extension is compatible with the muon measurement.&amp;lt;/p&amp;gt; </jats:p

A telescope based on Scintillator technology for assessing massive rock falls &amp;#8211; la reunion island

&amp;lt;p&amp;gt;A telescope based on scintillators technology has been installed at the footstep of giant cliffs for assessing massive rocks falls. Such an experience is a first in the &amp;amp;#8220;world of muography&amp;amp;#8221;. It was made possible thanks to the national geological service, the BRGM, in particular its regional branch based in Reunion Island. Muography was chosen because it allows to access the density variation in time and space, in a passive way, by collecting in the telescope the muons which crossed the rock. The telescope has been installed for up to 6 months at the footwall of the giant cliff.&amp;amp;#160; The rainy season was chosen as the acquisition window to be able to follow the density variations that occur in the massif during rainy events.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;The telescope is composed of 3 parallel ~1m&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt; active detection planes recording the positions and the precise time of the particles hits. The detector readout has been developed on the early concept of connected &amp;amp;#8220;smart sensors&amp;amp;#8221;. It allows an optimized selection of the particles hits to perform their tracking. A post-processing analysis will translate the recorded tracking properties into a detailed image of the target within the acceptance of the detector.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;La Reunion Island, located East of Madagascar, is composed of three shield volcanoes among with la Fournaise which is still active. The volcanic cirques are subjected to large-scale rock-falls (&amp;gt;10,000 m&amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;).&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;On the top of the wall (or Rempart), the target of our muography experiment, the decompression cracks are concentrated on a strip often equivalent to 10% of the height of the cliff. The cliff can be higher than 1,000 m. These cracks, sometimes more than a meter wide, delimit the rock scales likely to be crumbled. The origin of these cracks, which are almost vertical on the surface, is linked to the natural decompression of the massif by the vacuum. The geometry of these cracks at depth is not well known, but it is likely that they acquire a slightly concave shape, bringing them closer to the wall and cutting out large scales at the crest of the Rempart. The volume of rock falling highly depends on the depth of these cracks.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Our experiment is focused on the Ma&amp;amp;#239;do Rempart overlooking the western part of the Cirque of Mafate where the formations of the ancient volcanic outcrop in 1,000 m high scarps. We have installed a Muons telescope at &amp;amp;#8220;l&amp;amp;#8217;Ilet de Roche-Plate&amp;amp;#8221;, a small village located at the foot of active scree cones at the foot of the Ma&amp;amp;#239;do Rempart. This innovative experiment follows a fire that occurred on the top of the Rempart at the end of 2020, which led to an increase in falling blocks and a potential acceleration in the opening of cracks. One of the issues is to better delimit the volume of &amp;quot;fractured&amp;quot; rocks and if possible, to identify the depth of the decompression cracks that delimit the scales likely to fall.&amp;amp;#160;&amp;lt;/p&amp;gt;</jats:p

Muon tomography, seismic noise survey and multi-scale topographic monitoring to assess rockfall hazard at the Maido Rampart (La Réunion Island)

International audienceInstable rock compartments at the 1000 m high Maïdo rampart threaten the few dozen inhabitants of the islet of Roche Plate in Mafate located downslope, as well as the cliff top which is the second most popular touristic site of La Réunion Island (&gt;500 000 tourists/year). These rock compartments of a few tens of m3 to several hundred thousand m3 are pre-cut by fractures subparallel to the cliff as far as hundred meters from the cliff edge. In November 2020, reports of crack openings after an important bush fire raised fears of the imminent collapse of several hundred m3. The stability of other rock compartments was also considered worrying. In order to assess the stability of these compartments, a permanent multiscale and partly automated system was installed to survey crack openings and surface deformations. This set up was completed by a seismic noise survey designed to qualify the degree of individualization of rock compartments. Finally, a muon tomography survey of the upper part of the rampart was deployed to image the extension of crack roots. The acquired data should make it possible to better understand rupture processes and kinetics, helping in characterizing and managing rockfall hazard at this site

Phages rarely encode antibiotic resistance genes: a cautionary tale for virome analyses.

Antibiotic resistance genes (ARGs) are pervasive in gut microbiota, but it remains unclear how often ARGs are transferred, particularly to pathogens. Traditionally, ARG spread is attributed to horizontal transfer mediated either by DNA transformation, bacterial conjugation or generalized transduction. However, recent viral metagenome (virome) analyses suggest that ARGs are frequently carried by phages, which is inconsistent with the traditional view that phage genomes rarely encode ARGs. Here we used exploratory and conservative bioinformatic strategies found in the literature to detect ARGs in phage genomes, and experimentally assessed a subset of ARG predicted using exploratory thresholds. ARG abundances in 1181 phage genomes were vastly overestimated using exploratory thresholds (421 predicted vs 2 known), due to low similarities and matches to protein unrelated to antibiotic resistance. Consistent with this, four ARGs predicted using exploratory thresholds were experimentally evaluated and failed to confer antibiotic resistance in Escherichia coli. Reanalysis of available human- or mouse-associated viromes for ARGs and their genomic context suggested that bona fide ARG attributed to phages in viromes were previously overestimated. These findings provide guidance for documentation of ARG in viromes, and reassert that ARGs are rarely encoded in phages

Phages rarely encode antibiotic resistance genes: a cautionary tale for virome analyses

AbstractAntibiotic resistance genes (ARG) are pervasive in gut microbiota, but it remains unclear how often ARG are transferred, particularly to pathogens. Traditionally, ARG spread is attributed to horizontal transfer mediated either by DNA transformation, bacterial conjugation or generalized transduction. However, recent viral metagenome (virome) analyses suggest that ARG are frequently carried by phages, which is inconsistent with the traditional view that phage genomes rarely encode ARG. Here we used exploratory and conservative bioinformatic strategies found in the literature to detect ARG in phage genomes, and experimentally assessed a subset of ARG predicted using exploratory thresholds. ARG abundances in 1,181 phage genomes were vastly over-estimated using exploratory thresholds (421 predicted vs 2 known), due to low similarities and matches to protein unrelated to antibiotic resistance. Consistent with this, 4 ARG predicted using exploratory thresholds were experimentally evaluated and failed to confer antibiotic resistance in Escherichia coli. Re-analysis of available human-or mouse-associated viromes for ARG and their genomic context suggested that bona fide ARG attributed to phages in viromes were previously over-estimated. These findings provide guidance for documentation of ARG in viromes, and re-assert that ARG are rarely encoded in phages.</jats:p

Design, Construction and In Situ Testing of a Muon Camera for Earth Science and Civil Engineering Applications

The MUST2 (MUon Survey Tomography based on Micromegas detectors for Unreachable Sites Technology) camera is based on a thin Time Projection Chamber read by a resistive Micromegas. This innovative combination presents interesting distinctive features compared to existing muon detection technologies. It allows a wide angular acceptance of the detector with a low weight and compact volume, well adapted for confined spaces or underground operation. The current work presents the results obtained during the calibration measurements at the reference site, the Low Background Noise Laboratory (LBNL). Preliminary results from field measurement campaign carried out at the dam overlooking the village of Saint-Saturnin-les-Apt (South-East of France) are presented and discussed