Muon radiography is a promising technique for imaging the internal density structures of targets such as tunnels,pyramids,and volcanoes up to a scale of a few hundred meters by measuring the flux attenuation of cosmic...Muon radiography is a promising technique for imaging the internal density structures of targets such as tunnels,pyramids,and volcanoes up to a scale of a few hundred meters by measuring the flux attenuation of cosmic ray muons after they have traveled through these targets.In this study,we conducted experimental muon radiography of one of the volcanoes in the Wudalianchi area in Northeast China to image its internal density structure.The muon detector used in this study was composed of plastic scintillators and silicon photomultipliers.After approximately one and a half months of observing the crater and conduit of the Laoheishan volcano cone in Wudalianchi from September 23^(rd) to November 10^(th) 2019,more than 3 million muon tracks fulfilling the data selection criteria were collected.Based on the muon samples and high-resolution topography obtained through aerial photogrammetry using an unmanned aerial vehicle,a density image of the Laoheishan volcano cone was constructed.The results obtained in this experiment demonstrate the feasibility of using a radiography technique based on plastic scintillator detectors.To obtain the density distribution,we performed a detailed background analysis and found that low-energy charged particles dominated the background noise.Relatively higher densities were found near the surface of the volcanic cone,whereas relatively lower densities were found near the center of the volcanic cone.The experiment in this study is the first volcano muon tomography study performed in China.Our work provides an important reference for future research.展开更多
Cosmic ray muon radiography which has good penetration ability and is sensitive to high-Z materials, is an effective method to detect shielded nuclear materials. This paper summarizes methods developed to process muon...Cosmic ray muon radiography which has good penetration ability and is sensitive to high-Z materials, is an effective method to detect shielded nuclear materials. This paper summarizes methods developed to process muon radiography in Tsinghua University. The methods include detector data correction, reconstruction algorithms （maximum likelihood scattering, MLS, and the maximum likelihood scattering and displacement, MLSD） acceleration, and the modification of the normalized mean absolute distance measure （NMADM） into a picture comparison binarization method （PCBM） which is more suitable for cosmic ray muon radiographs. Simulations demonstrate that all these methods give excellent results, so that cosmic muon radiography can become more widely used.展开更多
This paper studies the possibility of using the scattering of cosmic muons to identify threatening high-Z materials. Various scenarios of threat material detection are simulated with the Geant4 toolkit. PoCA （Point o...This paper studies the possibility of using the scattering of cosmic muons to identify threatening high-Z materials. Various scenarios of threat material detection are simulated with the Geant4 toolkit. PoCA （Point of Closest Approach） algorithm reconstructing muon track gives 3D radiography images of the target material. Z-discrimination capability, effects of the placement of high-Z materials, shielding materials inside the cargo, and spatial resolution of position sensitive detector for muon radiography are carefully studied. Our results show that a detector position resolution of 50 μm is good enough for shielded materials detection.展开更多
基金supported by the National Natural Science Foundation of China(Nos.41974064,42174076 and U1865206)Young Elite Scientists Sponsorship Program by CAST(No.2019QNRC001).
文摘Muon radiography is a promising technique for imaging the internal density structures of targets such as tunnels,pyramids,and volcanoes up to a scale of a few hundred meters by measuring the flux attenuation of cosmic ray muons after they have traveled through these targets.In this study,we conducted experimental muon radiography of one of the volcanoes in the Wudalianchi area in Northeast China to image its internal density structure.The muon detector used in this study was composed of plastic scintillators and silicon photomultipliers.After approximately one and a half months of observing the crater and conduit of the Laoheishan volcano cone in Wudalianchi from September 23^(rd) to November 10^(th) 2019,more than 3 million muon tracks fulfilling the data selection criteria were collected.Based on the muon samples and high-resolution topography obtained through aerial photogrammetry using an unmanned aerial vehicle,a density image of the Laoheishan volcano cone was constructed.The results obtained in this experiment demonstrate the feasibility of using a radiography technique based on plastic scintillator detectors.To obtain the density distribution,we performed a detailed background analysis and found that low-energy charged particles dominated the background noise.Relatively higher densities were found near the surface of the volcanic cone,whereas relatively lower densities were found near the center of the volcanic cone.The experiment in this study is the first volcano muon tomography study performed in China.Our work provides an important reference for future research.
基金Supported by the National Natural Science Foundation of China(No. 10575059)the Program for New Century Excellent Talents in University (No. NCET-05-0060)the National Natural Science Foundation of China for Young Scholars (No. 10605015)
文摘Cosmic ray muon radiography which has good penetration ability and is sensitive to high-Z materials, is an effective method to detect shielded nuclear materials. This paper summarizes methods developed to process muon radiography in Tsinghua University. The methods include detector data correction, reconstruction algorithms （maximum likelihood scattering, MLS, and the maximum likelihood scattering and displacement, MLSD） acceleration, and the modification of the normalized mean absolute distance measure （NMADM） into a picture comparison binarization method （PCBM） which is more suitable for cosmic ray muon radiographs. Simulations demonstrate that all these methods give excellent results, so that cosmic muon radiography can become more widely used.
基金Supported by National Natural Science Foundation of China (10575046,10775062)Program for New Century Excellent Talents in University
文摘This paper studies the possibility of using the scattering of cosmic muons to identify threatening high-Z materials. Various scenarios of threat material detection are simulated with the Geant4 toolkit. PoCA （Point of Closest Approach） algorithm reconstructing muon track gives 3D radiography images of the target material. Z-discrimination capability, effects of the placement of high-Z materials, shielding materials inside the cargo, and spatial resolution of position sensitive detector for muon radiography are carefully studied. Our results show that a detector position resolution of 50 μm is good enough for shielded materials detection.
