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Mao L.,China Academy of Engineering Physics | An Z.,Sichuan University | Wu Q.Q.,China Academy of Engineering Physics | Wu Q.Q.,Sichuan University | And 3 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2012

In this paper, the effect of geometrical parameter's uncertainty of experimental setup in β-decay induced X-ray spectroscopy (BIXS) method has been studied. By varying deliberately the distance between the X-ray detector and the sample surface, the change of the tritium content and the tritium depth distribution obtained by the BIXS method has been observed. Both Monte Carlo simulations and experimental measurements were carried out for our BIXS experimental setup. It is found that the BIXS method will not give reliable tritium content and depth distribution of the sample if the sample-detector distance of the experimental setup is not measured accurately, i.e., the deviation of 1 mm of the sample-detector distance will cause ∼10% error of total tritium content besides of the distortion of the shape of tritium depth distribution. This indicates that the geometrical parameters of the experimental setup in the BIXS method must be accurately determined, especially the internal configuration of the X-ray detector used in the BIXS method. The measurement of the internal configuration of an X-ray detector used in the BIXS method by an industrial computed tomography (CT) has been shown in this paper. © 2012 Elsevier B.V. All rights reserved. Source


Xin J.,China Academy of Engineering Physics | He W.,China Academy of Engineering Physics | Shao J.,CAS Institute of Physics | Li J.,National X ray Digital Imaging Instrument Center | And 2 more authors.
Journal of Physics D: Applied Physics | Year: 2014

Dynamic fragmentation of metal under shock pressure is an important issue for both fundamental science and practical applications such as diagnostic equipment protection from fragment ejection of Au hohlraum in indirect drive laser fusion experiments, but the characteristic parameters of the fragments are scarce due to the limitation of dynamic diagnosis. In this paper we performed the laser-driven shock-loaded experiments at the Shenguang-III (SGIII) prototype laser facility, and a very low density (200mgcm-3) of poly4-methyl-pentene (PMP) foam set behind the free surface of the laser loading tin sample was used as a soft recovery device. The pressure near the free surface of the sample ranges from 9 to 43GPa. With our recently proposed method of detecting fragments within soft recovery devices, the fragment parameters of size, shape and penetration depth can be determined by x-ray micro-tomography and computed tomography reconstruction. Experimental results demonstrated that different dynamic failure mechanisms have great impact on the fragment parameters. © 2014 IOP Publishing Ltd. Source


Zhang C.,CAEP - China Academy of Engineering Physics | Zhang C.,National X ray Digital Imaging Instrument Center | Zhang C.,University of Electronic Science and Technology of China | Chen Y.,CAEP - China Academy of Engineering Physics | And 9 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2013

A wavelet domain Wiener filtering method is proposed for denoising of cone-beam dental CT images. The db4 wavelet is used to decompose the CT image, and the Wiener filtering is implemented in each scale of wavelet coefficients, while the parameters of local mean and noise variance estimation are adjusted based on region statistical characteristics in each scale of wavelet coefficients. New wavelet coefficients are used for the reconstruction of the denoised image, and the denoised CT image is obtained. The results of computer simulation and the cone-beam dental CT actual data prove that this method raises the reconstruction image's signal-to-noise ratio, suppresses image noise effectively, and then improves the image visual effect obviously. Source


He W.,CAEP - China Academy of Engineering Physics | Xin J.,CAEP - China Academy of Engineering Physics | Chu G.,CAEP - China Academy of Engineering Physics | Li J.,National X ray Digital Imaging Instrument Center | And 7 more authors.
Optics Express | Year: 2014

Studying dynamic fragmentation in shock-loaded metals and evaluating the geometrical and kinematical properties of the resulting fragments are of significant importance in shock physics, material science as well as microstructural modeling. In this paper, we performed the laserdriven shock-loaded experiment on the Shenguang-III (SGIII) prototype laser facility, and employed X-ray micro-tomography technique to give a whole insight into the actual fragmentation process. To investigate the size distribution of the soft recovered fragments from Poly 4-methyl-1-pentene (PMP) foam sample, we further developed an automatic analysis approach based on the improved watershed segmentation. Comparison results of segmenting fragments in slices with different methods demonstrated that our proposed segmentation method can overcome the drawbacks of undersegmentation and over-segmentation, and has the best performance in both segmentation accuracy and robustness. With the proposed automatic analysis approach, other parameters such as the position distribution and penetration depth are also obtained, which are very helpful for understanding the dynamic failure mechanisms. © 2014 Optical Society of America. Source


Chen H.,CAEP - China Academy of Engineering Physics | Chen H.,National X ray Digital Imaging Instrument Center | Chen Y.,CAEP - China Academy of Engineering Physics | Chen Y.,National X ray Digital Imaging Instrument Center | And 2 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2015

Beam hardening effect would be induced due to wide energy spectrum of X-ray. One efficient beam hardening correction method is building a mathematical law between poly-energetic projection and intersection length, which can be calculated by forward projection in reconstructed images domain. However, for local scanning, the intersection length obtained by forward projection is no longer equal to the real distance at which X-ray passes through the object, and the data of mathematical fit are not valid. Hence, a cylindrical phantom is used. Utilizing the geometrical character of cylinder, the true distance X-ray passing through the object is calculated analytically. Experimental result shows that beam hardening artifacts are suppressed by our approach. © 2015, Editorial Office of High Power Laser and Particle Beams. All right reserved. Source

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