GENERAL ASSEMBLY

Welcome Address

Overview of Muographers

The emerging technology of muography, a new visualization technique to look through gigantic objects with an elementary particle called the muon, is the focus of this conference. Recently the initial applications of muography to the study of structures such as pyramids and volcanoes have been expanding to include more commercial interests such as inspecting social infrastructures and energy and mineral resources. Evolutions of the research networks of muography will be discussed with particular attention to the chronological and lateral structures that could be an indicator of the development of this new technology.

Developments at the Virtual Muography Institute through the La Palma fault studies

Muography study of the La Palma fault is in progress with a small nuclear emulsion-based detector. The Virtual Muography Institute is providing the computing tools used for the simulation work and comparison with data. A report is given on the ongoing activity along with some insight into preliminary results.

Muography in the underground of Naples

Next to the study of volcanoes, muography allows the detection of cavities present in the subsoil and therefore lends itself to interesting applications related both to the safety of the territory and to archeology. The city of Naples, Italy, is particularly suitable for experimentation. The entire center of the city is crossed in its depth by an extensive network of underground passages and cavities. Most of these structures are of anthropic origin and go back as far as the VIII century before Christ, when the first Greek settlements, Partenope and then Naples, were founded. A first experimentation was conducted inside Monte Echia, home of the Partenope settlement. A known chamber was successfully revealed by demonstrating the capability of the method. The first campaign of measures showed, beside the signals of the known structures, a signal that could correspond to the presence of a cavity whose existence was suspected but was not be found with traditional methods, including the GeoRadar. Two further campaigns of measurements, conducted at different points and with two different detectors, confirmed the presence of the unknown vacuum and allowed to define its position and to reconstruct its shape in 3D. In addition to the study of the Neapolitan subsoil, a new campaign of measures is being prepared at the archaeological site of Cuma, near Naples, the first Greek colony in Italy and dating back to the 8th century before Christ. This ancient city also has a tuff hill that was intensely excavated by the Greeks first and then by the Romans. The exact position of many of these cavities are currently unknown and therefore the Cuma site is a very interesting place for experiment the potenziality of the muon radiography.

SCAN PYRAMID Muography Project

Khufu’s Pyramid, which is one of most famous archaeological heritage all over the world, was built on the Giza Plateau around 2500 BC. ScanPyramids is an international scientific research project organized by Egyptian Ministry of Antiquities to investigate four Egyptian Pyramids including the Khufu’s Pyramid by muography. Since 2015, we have been observing cosmic-ray muons inside the Khufu’s pyramids and we published our discovery of hidden structures until now. In this presentation, current status will be presented.

Reasons to investigate the structure of the pyramid in Lahun

There are two reasons to investigate the pyramid in Lahun that was built by Senuseret II: (A) to solve the mystery of the entrance location, and (B) to know how it was built. The entrances of all pyramids in the Old and Middle Kingdoms are situated in the north. While the entrance of the pyramid in Lahun has been found in south, it is still believed that there is a north entrance that can be imaged with muography. Regarding the structure of this pyramid, it has been considered that basic structure (diagonal cross shape) was made by limestones and then mudbricks were filled inside, and its surface was finally covered with high quality limestones. Therefore, the density contrast inside this pyramid can be imaged with muography to confirm how it was built.

Kufun Muography Project

There are around 160,000 Kofun (tombs) sites in Japan, most of which have not yet been subjects of academic research – either because there are so many or because excavation of every Kofun is not possible. If these sites can be surveyed through muography, a new era of archeological research can be expected. The present project is a collaborative project including researchers from Kansai University, Tokyo University, and the Wigner Research Center. Because there is no definitive evidence of being a Royal tomb, the first target is the Imashirozuka in Takatsuki City. Previous findings will be compared with the muography results, and, if successful, we intend to expand our research to other tombs in Japan.

Muography in a mining environment, a proof of concept in a decommissioned mine

Muography can be a resourceful technique in a mining environment. Indeed, it can detect voids forming alloying to trigger warning and counter measures but it can also detect left over deposits above the deepest tunnels. To assess the relevance of muography in this new environment, IRIS Instruments together with the BRGM (French Geological Survey) carried on a test inside a decommissioned iron mine at May sur Orne near Caen (North of France). The instrument was placed in the deepest non-submerged tunnel at about 50m underground in order to scan the upper level for unknown void. The map of the mine in possession of the BRGM (in charge of ancient French mines monitoring) is very incomplete as it is usually for very ancient mine (early 20’ century). The investigation area was chosen to be at the edge between known and unknown area to be able, firstly, to clearly identify known voids with muography and then to investigate the presence of uncharted voids. Moreover, since this mine is under a residential area, such voids are potential safety issues that have to be dealt with. Data have been taken during 3 month with a modified version of the telescope used during the ScanPyramids mission and leased by the CEA. Its structure and housing have been adapted to fit inside the tunnel and to ensure the detector stability in this damp environment. The analysis is still ongoing but upper tunnel and void are clearly visible proving the efficiency of the method. A gravimetrical and seismic survey will be performed by the BRGM at the same area in order to bring new information together with comparing resolution from each techniques.

Explorations of Hungarian Caves with Muography

Underground Muography is a promising possibility, despite its limitations, to study objects which may otherwise be very difficult to access. Natural caves are such a case example, and relevant for the Hungarian karst areas where complicated cave systems can develop. Access to the measurement site, power and maintenance all present challenges. The talk presents various experiences and recent detector developments, as well as demonstration of the viability of Muography, in these environments.

Lascaux and current topics on Paleolithic Cave Art

Lascaux Cave in southwest France has numerous magnificent paintings of 20 000 years ago. Current topics on Palaeolithic Cave Art are the C14 dating method, the Uranium-Thorium dating, the destruction and protection of cave art, and how to discover an underground space in cave.

Recent Developments in Sakurajima Muography Project

Mt. Sakurajima is one of the most active volcanoes with hundreds of explosive eruptions in every year. A Multi-wire-proportional-chamber-based Muography Observation System (MMOS) is under development in South-West direction at the distance of 2.8 kilometers from Showa crater at 125 meters ASL to monitor the muon flux and rock density variations below the crater regions. The MMOS is based on high angular resolution (3 mrad), low-power (10 Watts) tracking systems using the robust, light-weight (<10 kg), and high efficient (> 99 %) MWPC technology and custom-designed electronics. The high operational stability and high-definition imaging capability have been demonstrated during the first measurement period in 2017 (http://www.nature.com/articles/s41598-018-21423-9). A software framework has also been developed to MMOS for on-line data analysis and real-time monitoring of the variation of detector parameters of MMOS, muon flux and average density. Since October 2018, the MMOS is running with six MWPC-based tracking systems with the total sensitive surface of 4.5 square meters. The first experiences with the World’s largest Muography Observatory will be presented.

The MEV project and the muography of Etna North-East crater.

The MEV (Muography of Etna Volcano) project aims at the realization of a facility expressly designed for the muography of the top of Etna volcano. In particular, the North-East crater in the summit area of the volcano has been selected as the target for this experiment. A muon tracking telescope with high imaging resolution was built and tested during 2017. The telescope is a tracker based on extruded scintillating bars and an innovative read-out architecture. It is a tracker composed of three XY modules with a sensitive area of 1m²; the angular resolution not exceeds 0,4 msr and the total angular aperture is about 45°. The telescope is placed at about 3100 m a.s.l. and restarted data acquisition after being buried by the snow during last winter. Two measurement campaigns were performed in 2017 and 2018 (still running). The preliminary results and knowledge acquired will be discussed in the talk.

Recent Progresses on MURAVES

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Stromboli Muography Project

Precise knowledge of the internal structure of the summit region of Stromboli is of the great interest for explaining the eruption dynamics. Muography measurements using nuclear emulsions can provide data with the angular resolution better than 3 mrad, sufficient to observe the fine structure of the conduits in the craters area. Nevertheless the resolution of measurements can be spoiled by contribution of low-momentum component due to secondary particles arriving to the telescope from the nearby rocks. To get rid of this kind of background we installed the ECC (Emulsion Cloud Chamber) detector consisting of 10 double-sided emulsion plates interleaved with 9 lead plates. This compact (1.5 cm thick) structure, thanks to the micrometric resolution of the emulsion and the multiple scattering effect, can effectively reject significant part of the low-momentum background. Muon telescope with the sensitive area of 0.9 m2 was accumulating statistics during the four months of exposure in winter 2017-2018. The exposure and preliminary data will be presented in this talk.

Developments of the scanning microscope through the La Palma and Stromboli studies

The present generation of nuclear emulsion scanning microscopes followed the needs of high energy physics experiments. Nowadays, data taking campaigns at the La Palma fault and at Stromboli are driving the evolution of the scanning systems devoted to muography projects. Major improvements are expected on hardware as well as on the data taking and post-processing software.

Portable muography based on small and gas-tight Resistive Plate Chambers

We report on the first steps in the development of a small-size muon telescope based on glass Resistive Plate Chambers with small active area. The long-term goal of this project is to focus on applications of muography where the telescope may have to be operated underground and/or inside small rooms, and in challenging logistic situations. Driving principles in our design are therefore compact size, light weight, gas tightness, and robustness. The first data-taking experiences have been encouraging, and we elaborate on the lessons learnt and future directions for development.

Applications of the MIMA detector to geological prospecting

The Muon Imaging for Mining and Archaeology (MIMA) tracking detector has been conceived as a rugged and compact muographic system allowing to be easily transported, installed and spatially oriented in inhospitable environments as those characterizing underground mining sites or lands affected by hydrogeological instability. To meet these requirements, this detector has been designed in such a way as to minimize power consumption and maintenance needs, while maintaining the necessary reliability in order to perform long-term measurements without the presence of any operators. At the end of 2017 the MIMA apparatus was installed inside the Temperino mine, a touristic archaeological site in Campiglia Marittima, not very far from the Florence town (Italy), with the purpose of imaging a large known void of cultivation of Etruscan age located somewhere above the installation point. For approximately two months we have measured muons downstream of the overlying forty meters thick rock layer. Since then a second measurement in a different position was completed, with an exposition of approximately 45 days. The detector is now installed in an intermediate position to allow the reconstruction of 3D information. In the same period we have tested the same methodology for the study of the conservation status of damaged riverbanks.

Developments of muographic technologies at the University of Sheffield

In this talk I will briefly review a number of muon tomography activities the University of Sheffield is currently involved in. First, I will discuss CRESTA, a flexible GEANT4 wrapper developed to support the simulation needs of a diverse set of cosmic ray tomography projects. I will then present the status of CHANCE Horizon-2020 Work Package 4, the application of muon tomography to large volume and heterogenous cemented nuclear waste packages. Finally, I will present a low-cost scintillator based neutron detector prototype that is currently being developed for the monitoring of soil moisture content.

Muon telescope developed for the MEV project

The muon telescope developed for the MEV project is based on three XY position-sensitive (PS) planes, with a sensitive area of 1 m². Each PS plane consists of two layers of 99 plastic scintillating bars, (1 x 1 x 100 cm³) with an extruded central 2,5 mm hole inside, through which two 1 mm Wave Length Shifting fibres are embedded to transport the photons to a Position Sensitive PhotoMultiplier (PSPM). The plastic scintillator is coated with a white reflector on each external side. The sensitive modules are enclosed in a cubic box with external side of about 1,5 m. The mechanical and power design of the detector makes it able to work in the summit zone of Etna Volcano. The low power electronic chain, exploiting a smart read-out scheme, is full-custom designed for the purpose of the MEV project. The telescope is solar powered and the overall power consumption is about 20W.

Muon Portal Project

Muon tomography (3 dimensional muographic reconstruction technique) is a technique which exploits the multiple Coulomb scattering of highly penetrating cosmic ray-produced muons to perform non-destructive inspection of high-Z materials without the use of artificial radiation. A muon tomography detection system can be used as a portal monitor at border crossing points for detecting illegal targeted objects. The Muon Portal Project built a prototype of a real size detector (6m×3m×7m) for the inspection of a standard Twenty Foot Equivalent (TEU) container, namely about 6m×3m×3m, that was fully characterized and has provided the first 2D and 3D images. In the present Project, 4800 extruded scintillator strips were arranged such as to cover four X–Y detection planes (6m×3m), two placed above and two below the container to be inspected. Silicon photomultipliers were used as photosensors, to collect the light transported by Wave Length Shifter (WLS) fibres embedded in the scintillator strips. First tomographic images are here presented.

Muography Project at Kyushu University ~Energy Window Muography for Investigation of Infrastructure Degradation ~

Muography has been widely applying to various investigation of a huge object e.g. volcanos, pyramids, and so on. The muography technique also has potential to investigate degradations in smaller scale infrastructure buildings. We have proposed “Energy Window Muography (EWM)” to reduce measurement time for the smaller scale targets. The effectiveness has been revealed by simulation study. The simulation results and future tasks will be shown in the presentation.

T2DM2 Muography Project

The Temporal Tomography of the Densitometry by the Measurement of cosmic Muons (T2DM2) collaboration has developed a new tool for in-situ imaging and monitoring density of large volumes of matter with applications in civil engineering works or geological and hydrogeological volumes. The MUST² camera consists of a thin time projection chamber read by a resistive Micromegas, which presents interesting distinctive features: wide angular acceptance of the detector with a low weight and volume (well adapted for confined spaces or underground operation). The presentation provides an overview of the camera characterization tests, first field measurement and introduces the next stage of the project: the construction and deployment of a network of 20 autonomous cameras at the Low Background Noise Laboratory of Rustrel (LSBB), France.

Imaging the bedrock beneath Alpine glaciers with muography

I report on recent developments of muography applied in Alpine glaciers. The Eiger-mu collaboration, which consists of researchers of high energy physics and geologists of the University of Bern in Switzerland, proposes to apply the muography to map the bedrock geometry beneath active glaciers. The first feasibility test has been performed at the Jungfrau region, Central Swiss Alps, Switzerland. Detectors consisting of emulsion films were installed along the Jungfrau railway tunnel that runs through the bedrock under the Aletsch glaciers. The detectors were exposed about 50 days in the tunnel and recorded tracks of muons, which passed through the glacial ice and the underlying bedrock. After the films were extracted, they were chemically developed and scanned with fast and automated microscopes in the laboratory at the University of Bern. The analysis of the muon absorption rate enabled us to image a three-dimensional shape of the boundary between the dense bedrock (~ 2.7 g/cm³) and the light ice component (~ 0.8 g/cm³) in the very uppermost part the glacier with a resolution ranging from a few meters to 10 m.

Developments of Muography at LINKEOS Technologies

Lynkeos is the first company in the UK to specialise in the field of muography. It was founded in 2016 to commercialise the results of a 7-year research programme into muon imaging for nuclear waste containers that was funded by the UK’s Nuclear Decommissioning Authority (NDA) . In 2017 we were awarded a £1.6 million contract by Innovate UK for the First-of-a-Kind Deployment of a muon imaging system on a nuclear site. This system is now installed on the Sellafield site. The Lynkeos Muon Imaging Sytsem (MIS) consists of four scintillating fibre tracker modules using 64 channel MPAMTs as readout, two above and two below the object to track the muons. We also developed complex imaging algorithms to reconstruct a 3D image of the object and its contents. The design, construction and performance of Lynkeos MIS is presented along with first experimental and commercial results. The high-resolution images include the identification of small fragments of uranium within a surrogate 500-litre intermediate level waste container and metal inclusions within thermally-treated GeoMelt® R&D Product Samples.

Muogrpahic Imaging of the Buried Reinforced Concrete Structures

Human-made concrete structures, such as nuclear reactors, dams, bridges, tunnels, buildings are potential targets of cosmic-ray muography. A portable, low-power (5 Watts), high-resolution (10 mrad) tracking system has been developed for small-scale muography in cooperation of The University of Tokyo, Wigner Research Centre for Physics and NEC. The 20 cm-length tracking system consists of four layers of 32 x 20 cm²-sized Close Cathode Chambers (CCC) with the position resolution of 1.5 mm, a userfriendly, custom designed data acquisition system. The first prototype has been tested at the bottom of a 3-meter-deep shaft inside a small mound at NEC Tamagawa Plant. The tracking system operated reliably with the tracking efficiency above 95 % during the tests and the bottom of a buried reinforced concrete structure has successfully been visualized within few days with the resolution of 20 mrad x 20 mrad. The optimization of tracking system for borehole-muography is ongoing in cooperation with CRIEPI.

Muography Projects on imaging the Abandoned Mine

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