Zejie Yin

University of Science and Technology of China, Hefei, Anhui Sheng, China

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Publications (14)13.68 Total impact

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    ABSTRACT: Accurate measurement of flash X-ray energy spectra plays an important role in high-energy flash radiography. In this paper, by virtue of Geant4 toolkit, we simulated the generation and transport of X-ray photons resulting from the interaction of a high-energy electron beam with a solid thin target. We obtained the flash X-ray energy spectral distribution in the plane perpendicular to the electron beam incident direction. Our results indicate that the flash X-ray spectrum is almost uniform in the azimuthal direction but is quite different in the radius direction. Specifically, as the radius increases, the incident X-ray dose decreases significantly. Our work paves a theoretical basis for selecting appropriate structures and layout of the spectrometer and facilitates the measurements of flash X-ray energy spectra.
    Plasma Science and Technology. 11/2013; 15(11):1165-1168.
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    ABSTRACT: A FPGA-based real-time digital pulse shape discriminator has been employed to distinguish between neutrons (n) and gammas (γ) in the Neutron Flux Monitor (NFM) for International Thermonuclear Experimental Reactor (ITER). The discriminator takes advantages of the Field Programmable Gate Array (FPGA) parallel and pipeline process capabilities to carry out the real-time sifting of neutrons in n/γ mixed radiation fields, and uses the rise time and amplitude inspection techniques simultaneously as the discrimination algorithm to observe good n/γ separation. Some experimental results have been presented which show that this discriminator can realize the anticipated goals of NFM perfectly with its excellent discrimination quality and zero dead time.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 10/2012; 72C:30-34. · 1.09 Impact Factor
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    ABSTRACT: A novel compact real time radiation detector with cost-effective, ultralow power and high sensitivity based on Geiger counter is presented. The power consumption of this detector which employs CMOS electro circuit and ultralow-power microcontroller is down to only 12.8 mW. It can identify the presences of 0.22 μCi (60)Co at a distance of 1.29 m. Furthermore, the detector supports both USB bus and serial interface. It can be used for personal radiation monitoring and also fits the distributed sensor network for radiation detection.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 05/2012; 70(8):1667-70. · 1.09 Impact Factor
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    ABSTRACT: Due to their low cost, flexibility, and convenience for long distance data transfer, plastic scintillating fibers (PSFs) have been increasingly used in building detectors or sensors for detecting various radiations and imaging. In this work, the possibility of using PSF coupled with charge-coupled devices (CCD) to build area detectors for X-ray imaging is studied using a Monte Carlo simulation. The focus is on X-ray imaging with energy from a few 100 keV to about 20 MeV. It is found that the efficiency of PSF in detecting X-ray in this energy range is low. The performance can be improved by coating a PSF with X-ray absorption layers and the MTF of the system is presented. It seems possible to build such area detectors with PSFs for imaging hard X-rays under certain environment.
    Applied Radiation and Isotopes 03/2008; 66(2):162-7. · 1.18 Impact Factor
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    ABSTRACT: We describe a simple position sensitive γ-ray detector configuration and investigate its performance using a Monte Carlo simulation method. The detector is based on the characteristics of Compton scattering of high energy photons by electrons and the leakage of high energy photons from a rod shaped plastic scintillating fiber. Both energy and spatial resolution have been presented with energies in the range of 0.8–7 MeV, about 10% and a few centimeters, respectively. Cross-talk of the configuration has also been considered.
    Optical Fiber Technology 01/2008; · 1.19 Impact Factor
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    ABSTRACT: X- and gamma-rays' energy deposition in plastic scintillation fibers and fiber arrays in an energy range from 10 keV to 20 MeV has been studied using Monte Carlo simulations. The results show that the characteristics of the energy deposition in fibers are similar to that observed in bulk scintillation materials. The deposition efficiency increases with the fiber length, but the rate of increase drops as the length of the fibers is beyond 8 cm, suggesting such a length might be the optimum thickness of an imaging plate constructed using the scintillation fiber arrays. The results suggest that plastic scintillation fibers are useful for X- and gamma-ray imaging below about 1 MeV. For incident photons above that energy, the energy leakages from a fiber and crosstalk between fibers in an array become severe, which results in significant deteriorations in spatial resolution of the fiber arrays used for imaging.
    IEEE Transactions on Nuclear Science 11/2007; · 1.22 Impact Factor
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    ABSTRACT: In this work, characteristics of using PSFs (plastic scintillation fibers) coupled with CCD (charge-coupled devices) to build area detectors for high energy X-ray imaging are studied with a Monte Carlo simulation, which cover an energy range of a few hundred keV to about 20 MeV. It was found that the efficiency of PSF in detecting X-ray with energy above a few hundred keV is low. We can use large incident flux to increase the output signal to noise ratio (SNR). The performance can also be improved by coating PSF with X-ray absorption layers and the MTF of the system is presented. By optimizing the absorption layer thickness, the crosstalk of the area detector built with PSF decreases.
    Nuclear Science and Techniques 01/2007; 18(3):172-175. · 0.09 Impact Factor
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    ABSTRACT: The spatial resolution of a position sensitive gamma-ray detector configuration based on plastic scintillation fiber array was measured using a Monte Carlo simulation method. Both point spread function and modulation transfer function (MTF) were presented. The factors that influence the spatial resolution were also discussed. The results of the simulation showed that the intrinsic spatial resolution was consistent with the size of the physical pixels and a few centimeters spatial resolution could be obtained under certain circumstances.
    Nuclear Science and Techniques - NUCL SCI TECH. 01/2007; 18(2):111-114.
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    ABSTRACT: The mechanical properties of glassy films and glass surfaces have been studied using an atomic force microscope (AFM) through various imaging modes and measuring methods. In this paper, we discuss the viscoelastic response of a glassy surface probed using an AFM. We analyzed the force-distance curves measured on a glassy film or a glassy surface at temperatures near the glass transition temperature, Tg, using a Burgers model. We found that the material's characteristics of reversible anelastic response and viscous creep can be extracted from a force-distance curve. Anelastic response shifts the repulsive force-distance curve while viscous creep strongly affects the slope of the repulsive force-distance curve. When coupled with capillary force, due to the condensation of a thin layer of liquid film at the tip-surface joint, the anelasticity and viscous creep can alter the curve significantly in the attractive region.
    Journal of Colloid and Interface Science 06/2006; 297(1):104-11. · 3.17 Impact Factor
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    ABSTRACT: We describe a simple dissipative quartz crystal microbalance (QCM) and two simple methods for determining the dissipation factor. The microbalance consists of an oscillator circuit interfaced with a personal computer. The oscillation voltages are undersampled through a low speed data acquisition card. Both methods for determining the resonant frequency and the dissipation factor assume a limited variation of the resonant frequency, which is the case for general applications of QCMs. The first method directly fits the undersampled data with a nonlinear function. The second method determines the resonant frequency of a quartz crystal by Fourier transformation of the acquired data. The dissipation factor is obtained by rectifying the undersampled data and then fitting them with an exponential function.
    Review of Scientific Instruments 04/2006; · 1.60 Impact Factor
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    ABSTRACT: Positron annihilation lifetime spectroscopy (PALS) is a powerful technique to study the free volume in polymers. The lifetime of ortho-positronium (o-Ps), a bound state of an electron and a positron, can be used to assess the pore size while the intensity can be used to characterize the number of pores. On the basis of the values of the long-lived o-Ps components in the lifetime spectra, the radii and fractional free volumes in the sulfonated poly (2,6-dimethyl-1,4-phenyleneoxide) (SPPO) membranes with different amounts of LiCl were calculated. It was found that, with the increasing amount of LiCl, the free volume radius and the fractional free volume firstly increased and then decreased. After immersing the membranes in distilled water, the free volume radius and the fractional free volume changed with different water concentrations in the membrane.
    Plasma Science and Technology 01/2006; 8(5):573-576. · 0.51 Impact Factor
  • Guanwen Yang, Zejie Yin
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    ABSTRACT: Despite the fact that atomic force microscopy (AFM) has been increasingly used in the study of glass transitions in polymer films, the characteristic behaviors of viscoelastic response measured using AFM and their correlations with the macroscopic mechanic behavior of bulk samples are still to be understood. We have studied viscoelastic response of polymer films near their glass transitions using atomic force microscopy. The response of a polymer film probed by an atomic force microscope is calculated using a Burger's model with four adjustable parameters. It is found that the force distance curve measured with the AFM is strongly affected by the viscosity of the film. The exact shapes of the force distance curves depend on both the temperature and measuring speed. It is also found that the viscoelastic property of the film is strongly affected by the adhesion force between the AFM tip and the polymer film. Several characteristics in a force distance curve near the glass transition will be discussed
    03/2005;
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    ABSTRACT: The performance of a simple prototype X-ray detector composed of plastic scintillating fibers (PSF) coupled with a charge-coupled device (CCD) for X-ray imaging was evaluated using a Monte Carlo simulation. The advantage of this detector is its simplicity and very low cost. The results show that the imaging detector has a reasonable efficiency and sensitivity for imaging X-ray with energy below a few hundred keV. The resolution can be very good if the size of the PSF used is appropriately chosen. For higher energy X-ray, the efficiency is greatly reduced. Improvements are suggested which could make such imaging detector more suitable and even desirable under certain circumstances and when the low cost are essential.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 01/2005; · 1.27 Impact Factor
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    ABSTRACT: In this work, we demonstrated that the data acquisition for either computerized tomography (CT) or digital radiography (DR) could be achieved by using a single plastic scintillation fiber coupled with a photomultiplier. The method is simple and particularly useful for imaging small objects. We describe the experimental set-up and procedure used in obtaining images. We show that the results obtained by using this method are impressive and the method can be implemented in many laboratories to demonstrate the concept of radiation imaging.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 01/2004; 225(4):617-622. · 1.27 Impact Factor