Muon Absorption Research Articles

Accurate in situ rock density measurement with cosmic ray muon radiography

Muon radiography, which relies on measuring the absorption and attenuation of muons as they pass through matters, offers a new imaging technique capable of revealing the internal structure of large objects. Recent technological advancement allows for the application or testing of muon radiography in various fields, including mining, civil engineering, security check, etc. This study investigates the factors that influence muon radiography, which is used in density inversion, through simulations and experiments. The materials considered for density inversion include water, standard rock, and iron. Our simulation studies show that the number of events detected and selected has an impact on the reconstruction results, and several factors, such as multiple Coulomb scattering processes, recording time, and spatial resolution, which influence the number of muons, must be taken into account when measuring the rock density. We design and conduct a laboratory scale experiment based on the simulation results. We filter the 220 h of recording signals through time coincidence and straight-line fitting to obtain the selected events. Our results reveal that the statistical error of muons survival ratio in recording time significantly impacts the inversion result and decreases the error can improve accuracy greatly. In the experiment, the deviation between the inversion mean value and the expected value can be reduced to 2.4%–2.9% for iron, 7% for water, and 1.5% for standard rock. This density inversion approach provides insight into future density detection of underground structures.

Performance testing of gas-tight portable RPC for muography applications

This paper reports the latest developmental efforts for a position-sensitive glass-based Resistive Plate Chamber (RPC) and a multi-channel Data AcQuisition (DAQ) system tailored for muon tracking in muography applications. The designed setup prioritizes portability, aiming for field applications where both the detector and the DAQ operate effectively in external environmental conditions. Comprehensive discussions on hardware development activities and signal processing techniques are included, incorporating noise filtering to enhance the accurate detection of real muons. A muon absorption measurement has also been carried out to understand the behavior of these detectors from an application perspective.

MuGrid: A scintillator detector towards cosmic muon absorption imaging

Muography has a wide range of applications, especially in the cross-disciplinary area as it is a powerful tool to probe the internal composition of objects in a non-destructive way. We designed a cosmic muon tracking detector MuGrid using plastic scintillators. In this work, we present the preliminary progress of the MuGrid detector and its demonstrator, including the data acquisition system and Monte Carlo modeling of MuGrid. A case study is conducted in a tunnel as a validation of the whole system.

Exploring the potential of muon radiography for blast furnace assessments: advancements in non-invasive imaging and structural analysis

The BLEMAB European project (BLast furnace stack density Estimation through online Muon ABsorption measurements), the evolution of the previous Mu-Blast European project, is designed to investigate in detail the capability of muon radiography techniques applied to the imaging of the inner zone of a blast furnace. In particular, the goal of this collaboration is to characterize the internal region (so-called cohesive zone) where the slowly downward-moving material begins to soften and melt, which plays an important role in the performance of the blast furnace itself. In this contribution, we describe the state-of-the-art of the muon tracking system which is currently being developed and installed at a blast furnace on the ArcelorMittal site in Bremen (Germany). Moreover, we will present the GEANT4 simulation framework devised for this application together with the simulation results. Finally, we will show the possible contribution of multiple scattering effects to such peculiar applications.

MUCH: A compact imaging Čerenkov telescope for volcano muography

Significant progress has been made in the last years in the field of volcanic muography. This technique takes advantage of the large penetrating power of atmospheric muons and allows us to infer information about the internal structure of volcanoes observing the differential absorption of muons passing through the target. This, in conjunction with other monitoring techniques, can help to determine the state of activity of a volcano and to reduce the risk related to paroxysmal events. The main challenge in the application of this technique is given by the background noise, that affects detectors. To improve the signal-to-noise ratio it is necessary to use several detection layers and shielding plates that make the detector expensive and difficult to transport. In order to overcome these issues, the use of Imaging Atmospheric Čerenkov Telescopes (IACTs) devoted to muography has been recently proposed.Here we present the MUography CHerenkov (MUCH) telescope, a compact IACT specifically designed for volcano muography. The telescope design is characterized by a Schmidt-like optical system and a Silicon Photo-Multipliers (SiPMs) camera working at wavelengths between 280nm and 900nm, equipped with a fast read-out electronics capable to operate SiPMs contemporarily in charge integration and photon counting mode.

Geant4 Simulation of Muon Absorption in Concrete Layers

Muography requires a detailed understanding of the absorption of muons in the material situated between the muon source and the detector. A large-statistics (>3 billion event) Geant4 simulation was run to simulate the absorption of muons in different thicknesses of concrete layers and to determine the effect of the material on the energies of muons that were not absorbed. The Geant4 simulation included a simple detector placed directly behind the absorbing material. A Geant4 simulation was also run for the same detector for alpha sources with no absorbing material and the results of this simulation were compared to the signals from the physical detector built in the laboratory and measured using standard alpha sources. The large-statistics simulations using muons of different energies were compared to the predictions of muon absorption from existing literature. The results of the simulations were in good agreement with both the measured signals from the laboratory as well as the predictions from the literature and the general method is found to be well-suited for studies used for muography involving material layers of uniform thickness.

Three-dimensional muon imaging of cavities inside the Temperino mine (Italy)

Muon radiography (muography) is an imaging technique based on atmospheric muon absorption in matter that allows to obtain two and three-dimensional images of internal details of hidden objects or structures. The technique relies on atmospheric muon flux measurements performed around and underneath the object under examination. It is a non-invasive and passive technique and thus can be thought of as a valid alternative to common prospecting techniques used in archaeological, geological and civil security fields. This paper describes muon radiography measurements, in the context of archaeological and geological studies carried out at the Temperino mine (LI, Tuscany, Italy), for the search and three-dimensional visualisation of cavities. This mine has been exploited since Etruscan times until recently (1973), and is now an active tourist attraction with public access to the tunnels. Apart from the archaeological interest, the importance of mapping the cavities within this mine lies in identifying the areas where the extraction ores were found and also in the safety issues arising from the tourist presence inside the mine. The three-dimensional imaging is achieved with two different algorithms: one involving a triangulation of two or more measurements at different locations; the other, an innovative technique used here for the first time, is based on the back-projections of reconstructed muon tracks. The latter requires only a single muographic data tacking and is to be preferred in applications where more than one site location can be difficult to access. Finally the quality of the three-dimensional muographic imaging was evaluated by comparing the results with the laser scan profiles obtained for some known cavities within the Temperino mine.

MuGrid: A scintillator detector towards cosmic muon absorption imaging

Muography has a wide range of applications especially in the cross-disciplinary area. It is a powerful tool to probe the internal composition of objects in a non-destructive way. To achieve the goal of muography, it is essential to track muons as precisely as possible. We designed a cosmic muon tracking detector MuGrid using plastic scintillators. In this work, we present the preliminary progress of the MuGrid detector and its demonstrator, including the data acquisition system, characterization of plastic scintillators and Monte Carlo modeling of MuGrid. We also analyzed its detection efficiency, angular resolution, and provided a comparison of back-projection images of simulation and observation in an open environment. A case study is conducted in a tunnel as a validation of the whole system.

BLEMAB European project: muon imaging technique applied to blast furnaces

The BLEMAB European project (BLast furnace stack density Estimation through on-line Muon ABsorption measurements), evolution of the previous Mu-Blast European project, is designed to investigate in detail the capability of muon radiography techniques applied to the imaging of a blast furnace’s inner zone. In particular, the geometry and size of the so called “cohesive zone”, i.e. the spatial zone where the slowly downward moving material begins to soften and melt, that plays an important role in the performance of the blast furnace itself. Thanks to the high penetration power of the natural cosmic ray muon radiation, muon transmission radiography represents an appropriate non-invasive methodology for imaging large high-density structures such as blast furnaces, whose linear size can be up to a few tens of meters. A state-of-the-art muon tracking system, whose design profits from the long experience of our collaboration in this field, is currently under development and will be installed in 2022 at a blast furnace on the ArcelorMittal site in Bremen (Germany) for many months. Collected data will be exploited to monitor temporal variations of the average density distribution inside the furnace. Muon radiography results will also be compared with measurements obtained through an enhanced multipoint probe and standard blast furnace models.

Revisiting the Limits of Atmospheric Temperature Retrieval From Cosmic‐Ray Measurements

AbstractA priori, cosmic‐ray measurements offer a unique capability to determine the vertical profile of atmospheric temperatures directly from ground. However, despite the increased understanding of the impact of the atmosphere on cosmic‐ray rates, attempts to explore the technological potential of the latter for atmospheric physics remain very limited. In this paper, we examine the intrinsic limits of the process of cosmic‐ray data inversion for atmospheric temperature retrieval, by combining a detection station at ground with another one placed at an optimal depth, and making full use of the angular information. With that aim, the temperature‐induced variations in cosmic rays (c.r.) rates have been simulated resorting to the theoretical temperature coefficients WT(h, θ, Eth) and the temperature profiles obtained from the ERA5 atmospheric reanalysis. Muon absorption and Poisson statistics have been included to increase realism. The resulting c.r. sample has been used as input for the inverse problem and the obtained temperatures compared to the input temperature data. Relative to early simulation works, performed without using angular information and relying on underground temperature coefficients from a suboptimal depth, our analysis shows a strong improvement in temperature predictability for all atmospheric layers up to 50 hPa, nearing a factor 2 error reduction. Furthermore, the temperature predictability on 6‐h intervals stays well within the range 0.8–2.2 K. Most remarkably, we show that it can be achieved with small‐area m2‐scale muon hodoscopes, amenable nowadays to a large variety of technologies. For mid‐latitude locations, the optimal depth of the underground station is around 20 m.

Muon radiography simulation for underground palace of Qinshihuang Mausoleum

Muon radiography is a nondestructive imaging technology based on the naturally existing cosmic ray muons. Because cosmic ray muons have the strong ability to penetrate, muon radiography in which the absorption of muons through matter is utilized, is especially suitable for the imaging of large-scale objects. While the traditional geophysical technologies used in archeology have some limitations, muon radiography is expected to become a powerful supplement in the nondestructive detection of large-scale cultural relics. Based on Monte Carlo simulation method Geant4, the muon radiography of the underground palace of Qinshihuang Mausoleum is studied in this work. A model of the underground palace of Qinshihuang Mausoleum is set up with GEANT4 program according to the data acquired by the previous archaeological study of Qinshihuang Mausoleum’s inner structure, as well as a reference model without these inner structure. By investigating the differences between the muon fluxes obtained from the two models, the muon radiography image of the inner structure of the model can be obtained. During the simulation, the cosmic ray muon source is generated by sampling according to an empirical formula summarized by Reyna, which can accurately describe the energy spectrum and angular distribution of cosmic ray muons at sea level. In addition, two viewpoints are selected in order to determine the three-dimensional position of the chamber. The simulation data are processed by using an image reconstruction algorithm which can be described as the following three steps. Firstly, the counts of muons in different directions are converted into muon flux. Secondly, the muon flux of the reference model is deducted from that of the Qinshihuang Mausoleum model, and the angular coordinates of the chamber walls are determined. Finally, combined with the wall’s angular coordinates obtained from the two viewpoints and the relative position between the two viewpoints, the chamber size and its position are reconstructed according to the geometric relationship. The errors of the reconstructed chamber center position and the length of chamber walls are both approximately 7%. In this article, we conduct only a preliminary study of muon radiography applied to the nondestructive detection of Qinshihuang Mausoleum, but the results show that muon radiography can be a promising tool for the archeological study of Qinshihuang Mausoleum. In the follow-up study, more factors will be taken into consideration, including the details of Qinshihuang Mausoleum model, and the improvement of image reconstruction algorithm.

Principles and Perspectives of Radiographic Imaging with Muons.

Radiographic imaging with muons, also called Muography, is based on the measurement of the absorption of muons, generated by the interaction of cosmic rays with the earth’s atmosphere, in matter. Muons are elementary particles with high penetrating power, a characteristic that makes them capable of crossing bodies of dimensions of the order of hundreds of meters. The interior of bodies the size of a pyramid or a volcano can be seen directly with the use of this technique, which can rely on highly segmented muon trackers. Since the muon flux is distributed in energy over a wide spectrum that depends on the direction of incidence, the main difference with radiography made with X-rays is in the source. The source of muons is not tunable, neither in energy nor in direction; to improve the signal-to-noise ratio, muography requires large instrumentation, long time data acquisition and high background rejection capacity. Here, we present the principles of the Muography, illustrating how radiographic images can be obtained, starting from the measurement of the attenuation of the muon flux through an object. It will then be discussed how recent technologies regarding artificial intelligence can give an impulse to this methodology in order to improve its results.

A Compact Muon Tracker for Dynamic Tomography of Density Based on a Thin Time Projection Chamber with Micromegas Readout

Tomography based on cosmic muon absorption is a rising technique because of its versatility and its consolidation as a geophysics tool over the past decade. It allows us to address major societal issues such as long-term stability of natural and man-made large infrastructures or sustainable underwater management. Traditionally, muon trackers consist of hodoscopes or multilayer detectors. For applications with challenging available volumes or the wide field of view required, a thin time projection chamber (TPC) associated with a Micromegas readout plane can provide a good tradeoff between compactness and performance. This paper details the design of such a TPC aiming at maximizing primary signal and minimizing track reconstruction artifacts. The results of the measurements performed during a case study addressing the aforementioned applications are discussed. The current works lines and perspectives of the project are also presented.

Correlated charge noise and relaxation errors in superconducting qubits.

The central challenge in building a quantum computer is error correction. Unlike classical bits, which are susceptible to only one type of error, quantum bits (qubits) are susceptible to two types of error, corresponding to flips of the qubit state about the X and Zdirections. Although the Heisenberg uncertainty principle precludes simultaneous monitoring of X- and Z-flips on a single qubit, it is possible to encode quantum information in large arrays of entangled qubits that enable accurate monitoring of all errors in the system, provided that the error rate is low1. Another crucial requirement is that errors cannot be correlated. Here we characterize a superconducting multiqubit circuit and find that charge noise in the chip is highly correlated on a length scale over 600micrometres; moreover, discrete charge jumps are accompanied by a strong transient reduction of qubit energy relaxation time across the millimetre-scale chip. The resulting correlated errors are explained in terms of the charging event and phonon-mediated quasiparticle generation associated with absorption of γ-rays and cosmic-ray muons in the qubit substrate. Robust quantum error correction will require the development of mitigation strategies to protect multiqubit arrays from correlated errors due to particle impacts.

Examination the cosmic ray muon attenuation by heavy metal alloys

The ability of a muon telescope to detect high dense metal elements was experimentally determined in previous works. Recently, the muon absorption has become one of the most important data in the tomography technique. In the present study, the absorption coefficients of muon at ground level for heavy alloys, namely brass, steel and stainless steel have been successfully recorded. The experiment was performed in Bangi, Malaysia with coordinates of 101.78º E, 2.92º N and elevation of 30 m above sea level. Muon examination was made by muon telescopes contained of two Geiger-Muller detectors. The muon count rate graphs showed an initial increase, followed by a transition depth and then a decrease with the continuous increase of the alloys thickness. The transition points observed were reliable and consistent with the properties of the alloys. The absorption coefficient of brass was higher than the other alloys; therefore, brass could be detected by cosmic ray muons easily. The results confirmed that the larger the mass density of the alloy absorber, the higher the ability to absorb the muon. The attenuation stated by this experiment would be valuable for coming work on muon revealing procedures.

Muon absorption tomography of a lead structure through the use of iterative algorithms

The muon radiography technique is part of the straight-ray scanning imaging methods and it is usually employed to produce two-dimensional images of the integrated density in the radial direction from the detector position. However, in the literature there are already some examples of muon tomographies made by combining several measurements from different observation points. The work presented in this article fits into this line of research: a tomography of a target composed of lead blocks arranged in a non-trivial geometry was carried out by means of muon absorption radiography measurements. To solve the inversion problem, an iterative algorithm called SART was employed, obtaining better results than using a Chi-squared minimization.

Muon tomography with Micromegas: Archaeology, nuclear safety and new developments for Geotechnics.

Muon tomography, or muography, stands out as a non-invasive technique for the scanning of big objects’ internal structure. It relies on the measurement of the direction changes or absorption of atmospheric muons when crossing the studied object. Proposed several decades ago, the performance achieved in particle detectors in the last years, specially in terms of stability, robustness and precision, has enlarged the possible applications of this technique. Bulk Micromegas represent a well-known technology suitable for the construction of muon telescopes based on these detectors. Thus autonomous and portable instruments have been conceived and constructed at Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA), being able to perform muography measurements in-situ, next to the studied objects. At present, a new muon telescope concept is being developed at CEA, combining a Time Projection Chamber (TPC) readout by a 2D multiplexed bulk Micromegas. This new generation of detectors will enlarge the possible application fields of muography, being specially interesting for geotechnics.

Development of a non-destructive isotopic analysis method by gamma-ray emission measurement after negative muon irradiation

Variations in isotopic abundance provide useful information for various scientific fields. Herein we performed a feasibility study by non-destructive isotopic analysis of negative muons. We irradiated two lead plate samples, one with the natural isotopic composition and one enriched with 208Pb, with negative muons and observed the gamma rays from 208Tl with a half-life of 3 min generated via muon absorption by 208Pb during muon irradiation. The isotopic abundance of 208Pb in natPb was successfully determined without sample destruction from the gamma ray intensity to be 69%, which agreed well with the mass spectrometry results.

Design and Construction of a Muon Detector Prototype for Study the Galeras Volcano Internal Structure

Muon tomography is a technique based on the observation of the absorption of muons in matter, as the ordinary radiography does using X-rays. The interaction of cosmic rays with the atmosphere produce Extensive Air Showers, which provide an abundant source of muons. These particles can be used for multiple applications on muon tomography, in particular, to study the internal structure of different volcanoes edifices. It is necessary in any muon tomography experiment a particle detector that has the capability to be sensitive to muon interactions. Here we report a brief description of the first steps towards a complete design of a prototype particle detector to perform muon tomography in harsh conditions encountered in the surroundings of the Galeras Volcano. The mechanical design and fabrication processes of the supporting structure of the muon detector prototype, and first steps towards a future detector simulations on GEANT4 are described in this work.

First muography of Stromboli volcano

Muography consists in observing the differential absorption of muons – elementary particles produced through cosmic-ray interactions in the Earth atmosphere – going through the volcano and can attain a spatial resolution of tens of meters. We present here the first experiment of nuclear emulsion muography at the Stromboli volcano. Muons have been recorded during a period of five months by a detector of 0.96 m2 area. The emulsion films were prepared at the Gran Sasso underground laboratory and were analyzed at Napoli, Salerno and Tokyo scanning laboratories. Our results highlight a significant low-density zone at the summit of the volcano with density contrast of 30–40% with respect to bedrock. The structural setting of this part of the volcanic edifice controls the eruptive dynamics and the stability of the “Sciara del Fuoco” slope, which is affected by recurrent tsunamigenic landslides. Periodical imaging of the summit of the Stromboli volcano such as that provided by muography can become a useful method for studying the evolution of the internal structure of the volcanic edifice.