最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Some methods for measurement of radon and radon progeny are reviewed in this paper.(1) Filter method for the measurement of radon progeny. A general formula was developed for the filter method, which can be used conveniently. All the formula related with the filter method are the special cases of our formula and could be obtained by using a magnetic card and a TI-59 calculator.(2) Two-filter method for the measurement of radon. A general formula was developed for the two-filter method, which is a direct result of the formula given in ref. (12). J. W. Thomas' result could be obtained easily from it by using the reasonable diffusion coefficient.(3) Balloon method for the measurement of radon. Balloon method for the measurement of radon was developed in 1974. The air containing radon was taken into a nylon balloon with a sampling time t1 and sampling rate Q1. Radon progeny activity was removed by a filter. After a certain duration t2, the air was taken out from the ballon with the time t3. When air was taken out, it passed the another filter. The a counts on this filter in the time interval T1→T2 canbe calculated by a general formula. For one sampling, the measurement can be finished within 25 mins with the sensitivity of 0.01~0.005 pCi/I, which is much more sensitive than the two-filter method, and also, faster and more convenient.The calculated results are compared with the experimental values and the agreements are quite good.
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发布时间：2022-08-16 - 摘要：In this paper, the principle, experimental arrangement and computer program of fundamental parameters method in radioisotope source excited energy dispersive X-ray analysis are described. In the calculation of the experimental data, the secondary fluorescent X-ray intensity was considered with the tertiary neglected. Both GaAs and CdTe as well as stainless steel specimens were analyzed by this method. The results were compared with the known values. The accuracy and precision were about 1%, respectively. No calibration standards were required. The method is non-destructive. The results demonstrate that this method is reliable and efficient.
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发布时间：2022-08-16 - 摘要：The principle and methods of thermal neutron radiography are described briefly in this paper. Emphasis is put on the discussion about the sensitivity of thermal neutron radiography in defect detecting test and those factors which affect the sensitivity and the quality of the images. Pictures obtained in various conditions are also presented.
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发布时间：2022-08-16 - 摘要：In this paper, we calculated the counting losses due to pile-up pulses rejected for spectroscopy with constant counting rates. The live time correction to compensate this counting losses was described.
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发布时间：2022-08-16 - 摘要：It was shown that the crude extracts of Ehrlich ascites carcinoma which contain the activities of thymidine kinase and thymidine monophosphate kinase and diphosphate kinase can effectively catalyze the synthetic reaction of 3H-TTP from the substracte—3H-thymidine (TdR). The conversion rate of TdR to TTP by these extracts was more than 75%, higher than those by rat regenerating liver and yeast. A method for complete separation of 3H-TdR and 3H-TTP was established using DEAE-Sephadex A-25 column chromatography, and then eluting with ammonium bicarbonate. The product was salt free. The optimum conditions for the reaction were ATP and enzyme Mg++ (11µmol each), reaction time 2hr. at 37℃ and enzyme protein, less than 5mg per milliliter reaction volume.
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发布时间：2022-08-16 - 摘要：A method for making a self-supporting boron target of high purity (99.999%)with resistance-heating is described. With this method, we succeeded in making the self supporting boron target of φ12 mm, and of thickness 50~200 µg/cm2. It has been satisfactorily applied to backscattering in nuclear physics experiments.
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发布时间：2022-08-16 -
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