arXiv subjects

Stylianos Chatzidakis

Publications and source records attributed to Stylianos Chatzidakis.

28 records · Page 2Linked to original sources

arXiv2022

Fieldable Muon Momentum Measurement using Coupled Pressurized Gaseous Cherenkov Detectors

Cosmic ray muons present a large part of the radiation background and depending on the application of interest muons can be seen as background noise, e.g., radiation mapping, radiation protection, dosimetry, or as a useful interrogation probe such as cosmic ray muon tomography. It is worth noting recent developments on muon scattering tomography which has emerged as a prospective noninvasive monitoring method for many applications including spent nuclear fuel cask monitoring and geotomography. However, it is still very challenging to measure muon momentum in the field, despite the apparent benefits, without resorting to large and expensive calorimeters, ring imagers, or time of flight detectors. Recent efforts at CNL and INFN have developed large prototypes based on multiple Coulomb scattering coupled with the muon momentum reconstruction algorithms. While these efforts show promise, no portable detectors exist that can measure muon momentum in the field. In this work, we present a new concept for measuring muon momentum using coupled pressurized gaseous Cherenkov radiators. By carefully selecting the gas pressure at each radiator we can optimize the muon momentum threshold for which a muon signal will be detected. This way, a muon passing through the radiators will only trigger those radiators with momentum threshold less than the actual muon momentum. By measuring the presence of Cherenkov signals in each radiator, our system can then estimate the muon momentum. The primary benefit of such a concept is that it can be compact and portable enough so that it can be deployed in the field separately or in combination with existing tomography systems.

physics.ins-det↗

arXiv2022

Fieldable muon spectrometer using multi-layer pressurized gas Cherenkov radiators and its applications

Cosmic ray muons have been considered as a non-conventional radiation probe in various applications. To utilize cosmic ray muons in engineering applications, two important quantities, trajectory and momentum, must be known. The muon trajectories are easily reconstructed using two-fold detector arrays with a high spatial resolution. However, precise measurement of muon momentum is difficult to be achieved without deploying large and expensive spectrometers such as solenoid magnets. Here, we propose a new method to estimate muon momentum using multi-layer pressurized gas Cherenkov radiators. This is accurate, portable, compact (< 1m3), and easily coupled with existing muon detectors without the need of neither bulky magnetic nor time-of-flight spectrometers. The results show that not only our new muon spectrometer can measure muon momentum with a resolution of +-0.5 GeV/c in a momentum range of 0.1 to 10.0 GeV/c, but also we can reconstruct cosmic muon spectrum with high accuracy (~90%).

physics.ins-det↗

arXiv2021

A Compact High-Resolution Muon Spectrometer Using Multi-Layer Gas Cherenkov Radiators

In both particle physics and cosmic ray muon applications, a high-resolution muon momentum measurement capability plays a significant role not only in providing valuable information on the properties of subatomic particles but also in improving the utilizability of muons. Currently, muon momentum is estimated by reconstructing the muon path using a strong magnetic field and muon trackers. Alternatively, time-of-flight or multiple Coulomb scattering techniques are less frequently applied, especially when there is a need to avoid using a magnetic field. However, the measurement resolution is much lower than that of magnetic spectrometers, approximately 20% in the muon momentum range of 0.5 to 4.5 GeV/c whereas it is nearly 10% or less when using magnets and trackers. Here, we propose a different paradigm to estimate muon momentum that utilizes multi-layer pressurized gas Cherenkov radiators. Using the fact that the gas refractive index varies with pressure and temperature, we can optimize the muon Cherenkov threshold momentum for which a muon signal will be detected. By analyzing the optical signals from Cherenkov radiation, we show that the actual muon momentum can be estimated with a minimum resolution of +-0.05 GeV/c for a large number of radiators over the range of 0.1 to 10.0 GeV/c. The results also show that our spectrometer correctly classifies the muon momentum (~87% classification rate) in the momentum range of 0.1 to 10.0 GeV/c. We anticipate our new spectrometer will to provide an alternative substitute for the bulky magnets without degrading measurement resolution. Furthermore, we expect it will significantly improve the quality of imaging or reduce the scanning time in cosmic muon applications by being incorporated with existing instruments.

physics.ins-det↗

arXiv2021

A Cosmic Ray Muon Spectrometer Using Pressurized Gaseous Cherenkov Radiators

In this work, we propose a new approach to cosmic ray muon momentum measurement using multiple pressurized gaseous Cherenkov radiators. Knowledge of cosmic ray muon momentum has the potential to significantly improve and expand the use of a variety of recently developed muon-based radiographic techniques. However, existing muon tomography systems rely only on muon tracking and have no momentum measurement capabilities which reduces the image resolution and requires longer measurement times. A fieldable cosmic ray muon spectrometer with momentum measurement capabilities for use in muon scattering tomography is currently missing. We address this challenge by optimally varying the pressure of multiple gaseous Cherenkov radiators and identifying the radiators that are triggered by muons that have momentum higher than the Cherenkov threshold momentum. We evaluate the proposed concept through Geant4 simulations and demonstrate that the cosmic ray muon momentum spectrum can be reconstructed with sufficient accuracy and resolution for two scenarios: (i) a perfect Cherenkov muon spectrometer and (ii) a practical spectrometer where noise is introduced in the form of scintillation and transition radiation photons. To quantify the accuracy of spectrometer, the concept of true and false classifications are introduced. The fraction of true classification is investigated for each momentum level in a practical radiator. The average classification rate for momentum range of 0.2 to 7.0 GeV/c with uncertainty of 1 GeV/c is approximately 85%.

physics.ins-det↗

arXiv2021

Effective Solid Angle Model and Monte Carlo Method: Improved Estimations to Measure Cosmic Muon Intensity at Sea Level in All Zenith Angles

Cosmic muons are highly energetic and penetrative particles and these figures are used for imaging of large and dense objects such as spent nuclear fuels in casks and special nuclear materials in cargo. Cosmic muon intensity depends on the incident angle (zenith angle). The low intensity of cosmic muon requires a long measurement time to acquire statistically meaningful counts. Therefore, high-energy particle simulations e.g., GEANT4, are often used to guide measurement studies. However, the measurable cosmic muon count rate changes upon detector geometry and configuration. Here we develop an effective solid angle model to estimate experimental results more accurately than the simple cosine-squared model. We show that the cosine-squared model has a large error at high zenith angles, whereas our model provides improved estimations at all zenith angles. We anticipate our model will enhance the ability to estimate actual measurable cosmic muon count rates in muon imaging applications by reducing the gap between simulation and measurement results. This will increase the value of modeling results and improve the quality of experiments and applications in muon detection and imaging.

physics.ins-det↗

arXiv2020

Automated detection of corrosion in used nuclear fuel dry storage canisters using residual neural networks

Nondestructive evaluation methods play an important role in ensuring component integrity and safety in many industries. Operator fatigue can play a critical role in the reliability of such methods. This is important for inspecting high value assets or assets with a high consequence of failure, such as aerospace and nuclear components. Recent advances in convolution neural networks can support and automate these inspection efforts. This paper proposes using residual neural networks (ResNets) for real-time detection of corrosion, including iron oxide discoloration, pitting and stress corrosion cracking, in dry storage stainless steel canisters housing used nuclear fuel. The proposed approach crops nuclear canister images into smaller tiles, trains a ResNet on these tiles, and classifies images as corroded or intact using the per-image count of tiles predicted as corroded by the ResNet. The results demonstrate that such a deep learning approach allows to detect the locus of corrosion via smaller tiles, and at the same time to infer with high accuracy whether an image comes from a corroded canister. Thereby, the proposed approach holds promise to automate and speed up nuclear fuel canister inspections, to minimize inspection costs, and to partially replace human-conducted onsite inspections, thus reducing radiation doses to personnel.

cs.CV↗

arXiv2019

Monte Carlo Characterization of the Cosmic Ray Muon Flux in Subsurface Geological Repositories

Recent challenges in monitoring subsurface geological repositories call for new, innovative concepts that are facility independent, cost-effective, passive, and reliable. Inspection and verification of future disposal facilities will exert significant pressure on the limited safeguards resources. Compared to aboveground facilities, subsurface geological repositories cannot be directly monitored. Once nuclear material is in place in these facilities, reverifying the inventory may no longer be feasible if continuity of knowledge is lost or updated safeguards information on the contents (or lack thereof) becomes available to inspectors. Using cosmic ray muons presents several potential advantages over conventional photon/neutron signatures, and their use in safeguards applications has only recently received attention. However, there have been limited efforts to explore the integration of cosmic ray muons into repository safeguards and study potential gains, risks, and costs. This paper presents a Monte Carlo-based methodology to characterize the cosmic ray muon flux, including muon angular and energy differential distributions at depths representative of geological repositories. This work discusses the feasibility of muon monitoring for detecting spent nuclear fuel disposal cask movement or for unauthorized excavation and rock removal. The objective is to develop useful parametrizations to provide a convenient tool for detector-specific and safeguards applications at any geological repository site. It is expected these results will provide a better understanding of how muons can be integrated into an existing geological repository safeguards framework.

physics.comp-ph↗

arXiv2018

Muon Tracing and Image Reconstruction Algorithms for Cosmic Ray Muon Computed Tomography

Cosmic ray muon computed tomography (μCT) is a new imaging modality with unique characteristics that could be particularly important for diverse applications including nuclear nonproliferation, spent nuclear fuel monitoring, cargo scanning, and volcano imaging. The strong scattering dependence of muons on atomic number Z in combination with high penetration range could offer a significant advantage over existing techniques when dense, shielded containers must be imaged. However, μCT reconstruction using conventional filtered back-projection is limited due to the overly simple assumptions that do not take into account the effects of multiple Coulomb scattering prompting the need for more sophisticated approaches to be developed. In this paper, we argue that the use of improved muon tracing and scattering angle projection algorithms as well as use of an algebraic reconstruction technique should produce muon tomographic images with improved quality or require fewer muons to produce the same image quality compared to the case where conventional methods are used. We report on the development and assessment of three novel muon tracing methods and two new scattering angle projection methods for μCT. Simulated dry storage casks with single and partial missing fuel assemblies were used as numerical examples to assess and compare the proposed methods. The simulated images showed an expected improvement in image quality when compared with more conventional techniques, even without muon momentum information, which should lead to improved detection capability, even for partial defects.

physics.ins-det↗

arXiv2018

A Generalized Muon Trajectory Estimation Algorithm with Energy Loss for Application to Muon Tomography

This work presents a generalized muon trajectory estimation (GMTE) algorithm to estimate the path of a muon in either uniform or nonuniform media. The use of cosmic ray muons in nuclear nonproliferation and safeguards verification applications has recently gained attention due to the nonintrusive and passive nature of the inspection, penetrating capabilities, as well as recent advances in detectors that measure position and direction of the individual muons before and after traversing the imaged object. However, muon image reconstruction techniques are limited in resolution due to low muon flux and the effects of multiple Coulomb scattering (MCS). Current reconstruction algorithms rely on overly simple assumptions for muon path estimation through the imaged object. For robust muon tomography, efficient and flexible physics based algorithms are needed to model the MCS process and accurately estimate the most probable trajectory of a muon as it traverses an object. In the present work, the use of a Bayesian framework and a Gaussian approximation of MCS are explored for estimation of the most likely path of a cosmic ray muon traversing uniform or nonuniform media and undergoing MCS. The algorithm's precision is compared to Monte Carlo simulated muon trajectories. It was found that the algorithm is expected to be able to predict muon tracks to less than 1.5 mm RMS for 0.5 GeV muons and 0.25 mm RMS for 3 GeV muons, a 50 percent improvement compared to SLP and 15 percent improvement when compared to PoCA. Further, a 30 percent increase in useful muon flux was observed relative to PoCA. Muon track prediction improved for higher muon energies or smaller penetration depth where energy loss is not significant. The effect of energy loss due to ionization is investigated, and a linear energy loss relation that is easy to use is proposed.

physics.comp-ph↗

arXiv2016

Analysis of Spent Nuclear Fuel Imaging Using Multiple Coulomb Scattering of Cosmic Muons

Cosmic ray muons passing through matter lose energy from inelastic collisions with electrons and are deflected from nuclei due to multiple Coulomb scattering. The strong dependence of scattering on atomic number Z and the recent developments on position sensitive muon detectors indicate that multiple Coulomb scattering could be an excellent candidate for spent nuclear fuel imaging. Muons present significant advantages over existing monitoring and imaging techniques and can play a central role in monitoring nuclear waste and spent nuclear fuel stored in dense well shielded containers. The main purpose of this paper is to investigate the applicability of multiple Coulomb scattering for imaging of spent nuclear fuel dry casks stored within vertical and horizontal commercial storage dry casks. Calculations of muon scattering were performed for various scenarios, including vertical and horizontal fully loaded dry casks, half loaded dry casks, dry casks with one row of fuel assemblies missing, dry casks with one fuel assembly missing and empty dry casks. Various detector sizes (1.2 m x 1.2 m, 2.4 m x 2.4 m and 3.6 m x 3.6 m) and number of muons ($10^{5}, 5\cdot10^{5}, 10^{6}$ and $10^{7}$) were used to assess the effect on image resolution. The Point-of-Closest-Approach (PoCA) algorithm was used for the reconstruction of the stored contents. The results demonstrate that multiple Coulomb scattering can be used to successfully reconstruct the dry cask contents and allow identification of all scenarios with the exception of one fuel assembly missing. In this case, an indication exists that a fuel assembly is not present; however the resolution of the imaging algorithm was not enough to identify exact location.

physics.comp-ph↗