最新刊期
      卷 0 ， 期 0 ， 2020
      • Wang Zihua Wang Gongli Li Binfang Mao Zhenlin
        Issue 4, (1991)
        摘要：The measurement of magnetic field distribution of the wide range magnetic spectrometer is carried out by a magnetometer with a temperature stabilized Hall element which has a long time stability of 0.03%. The magnetometer is calibrated with a NMR meter in the magnetic field range of 0.7-2.1 T. For below the calibrated region a fitting formula is presented. It is applicable to both positive and negative magnetic field regions.  
          
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        发布时间：2021-04-20
      • Zheng Wanhui Peng Yuqing Zhang Yiping
        Issue 4, (1991)
        摘要：An unfolding method to obtain intrinsic distributions of positron annihilation radiation from Doppler broadening spectra by means of an iterative method is described. The intrinsic distribution can be fitted into a Gaussian function and an invert parabola function. Electron momentum distribution and Fermi energy can be calculated.Positron annihilation spectra for 13 materials were analyzed. Their momentum distribution and Fermi energy were obtained. The results show that electron momentum distributions for various materials are different and experimental values of Fermi energy for various materials are consistent with theoretical ones. The study on amorphous and crystalline Fe-Si-B alloys indicates that momentum distributions are almost the same, while there is a small difference on Fermi energy.  
          
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        发布时间：2021-04-20
      • Gao Naifei Liu Yuanyuan Feng Yingqi
        Issue 4, (1991)
        摘要：Mossbauer spectra of both Model 6542 high-speed steel and pure iron have been measured at different temperatures （26℃≤T≤530℃） . The experimental data were fitted and their recoilless factors were obtained. The temprature-phase dependence of 6542 high speed steel is discussed.  
          
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        发布时间：2021-04-20
      • Zhang Tonghe Ji Chengzhou Kan Xiwen Shen Jinghua Tan Fujin Chen. Jun Yang Jianhua
        Issue 4, (1991)
        摘要：The friction coefficient of the surface of H13 sieel reduces by a factor of two after implanted by Sn, Ft is shown from SEM observations that the weared surface of implanted samples is smooth. The peak position of concentration profile measured by RBS is about 30 nm deeper than the calculated value, indicating an obvious enhanced diffusion during ion implantation. The extension of the concentration profile after annealing is greater than before. The FeSn2 phases are found by using X-ray diffraction and they still remain in the implanted layer after annealing.  
          
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        发布时间：2021-04-20
      • Li Xiaoqin Lin Chenglu Yang Genqing Zhou Zuyao Zou Shichang
        Issue 4, (1991)
        摘要：Defects in （100） Si implanted with 147 keV, 2 ×1015/cm2 BF2+ at room temperature were studied as a function of the implant current. The beam current varied from 20 to 140μA （dose rate 0. 41-2. 86μA/cm2）. Using the grazing angle RBS-channeiing （scattering angle θ= 97°） instead of the conventional one （θ=165°）, details of the damage distribution in near surface region （10-100nm depth） were analyzed. It was demonstrated that at an interested beam current no thermally-induced defect annealing was observed in bulk region while in near surface region （-30nm） the molecular effects would contribute to the beam current effects observed.  
          
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        发布时间：2021-04-20
      • Zhang Yingji Wei Yongqin Wang Qiuyu Qian Wenguo Zhang Xilin Chen Maobo
        Issue 4, (1991)
        摘要：A particle detector designed for the high-sensitivity small cyclotron mass spectremetry was made and tested. The detector consists of an Al2O3 conversion dynode, a microchannel-plate e’etron multiplier and an anode. Each ion that strikes the dynode at 80° angle ejects a few tens of secondary electrons, which enter separate channels of the microchanne’-piate and are then independently multiplied to a saturated pulse height. The charge collected by the anode is proportional to the ion energy. This permits a pulse-height discrimination against background. Data taken in an isotope separator are extrapolated and the background rate is found to be lower than 10-3/s at 90% efficiency for 40keV K or Ar ions. The energy resolution of the detector is 6.5keV, suitable for the spectrum measurement of very low energy ions.  
          
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        发布时间：2021-04-20
      • Yu Fengqiao Zhou Baoguo Sun Ankang Li Zuoqian
        Issue 4, (1991)
        摘要：The bi4π counting method as a new fundamental method of activity measurement is introduced. Suitable for more radionuclides, the method can achieve an accuracy of 0.03-0.6% (1σ in principle. The correctness of this method is verified by the measurements of 60Co sources, and it is found readily to reach an accuracy of 0.2% . The results are compared with those obtained by the 4πβ-γ coincident method, and both are in agreement within-the measurement error. Finally, the range of application for this method is also discussed.  
          
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        发布时间：2021-04-20
      • Zhou Sunxuan Huazhong University of Science and Technology)
        Issue 4, (1991)
        摘要：To determine the sign of calibration constant is essential in the calibration of a Mos-sbauer spectrometer. In this paper the correspondence between velocity wave-form and background form of Mossbauer spectrum is discussed and a method is presented to determine the sign of calibration constant according to the background form.  
          
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        发布时间：2021-04-20
      • Song Quanzun
        Issue 4, (1991)
        摘要：In the paper was described a full automatic device for determination of uranium content by delayed neutron counting. All processes, including changing, transfer and irradiation of sample; acquisition, transfer and treatment of data were automatically controlled by micro-computer IBM-PC.  
          
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        发布时间：2021-04-20
      • Zhang Ruyuan Li Luwei Xue Zhaonan
        Issue 4, (1991)
        摘要：Using the basic excitation equation, an expression of the optimum incident anlge was obtained as a function of the ratio of mass absorption coefficients for original and secondary X rays. With the source-sample-detector geometry designed according to the calculated optimum incident angle, the intensity of low energy secondary X ray emitted from a thick sample was increased by 20% and additional 20% improvement in detection efficiency was expected. With an elliptic cone shaped aluminum source collimating aperture, the edge of which was cut at a certain angle, the scattering background could be reduced significantly.  
          
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        发布时间：2021-04-20
      • Shen Wenxiu Ding Xingnong Zhu Jianhuan
        Issue 4, (1991)
        摘要：The newly developed Model NF-86 and NF-87 radicchromic nylon film dosimeters were manufactured from the host of nylon, with HPR-CN and PR-CN as radiochromic dye respectively. In this paper the results of the comparative study of NF-86, NF-87 with FWT-60 （a U. S. A. product） dosimeters were described, which show that the main dosimetric characteristics of NF-86, NF-87 and FWT-60 dosimeters were almost the same. The NF-86 and NF-87 can therefore serve as simple, quick and reliable means for routine dose monitoring （ranging 103-105 Gy） in radiation processing.  
          
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        <引用本文> <批量引用> 8935126 false
        发布时间：2021-04-20
      • Zhao Kejian Ma Bin
        Issue 4, (1991)
        摘要：The measurement of tritium in milk by means of the combustion sample preparation is described. The sample was prepared in a simple quartz combustion apparatus and Model HR-1 honeycomb combustion catalyst was used. 3H was measured in a low-background liquid scintillation counter. The efficiency of the combustion apparatus was evaluted b> recoveries of water and tritium. The recovery of water from milk was about 98.6% while the recovery of tritium from water or organism was equal to about 97%.  
          
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        发布时间：2021-04-20
      • Xu Zhixiang
        Issue 4, (1991)
        摘要：Influence of electron irradiation on backward breakdown voltage of semiconductor devices was discussed. The experimental results showed that avalanche breakdown voltage for diodes fell slightly while it rose a little for power transistors and thyristors.  
          
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        发布时间：2021-04-20
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