| 摘要 |
1,193,840. Photo-electric measurement of particle size. NATIONAL RESEARCH DEVELOPMENT CORP. Aug.30, 1968 [Sept. 20, 1967], No. 42875/67. Addition to 1, 127, 342. Heading G1A. The invention of the parent Specification is modified in that instead of measuring the intensities of two beams of different energies or energy bands, which have been transmitted by the fluid under test, fluorescent radiation from the fluid is investigated. Thus, in the arrangement of Fig. 2, X-rays from two sources S 1 , S 2 of different energies irradiate the flowing fluid. The energy of one beam is chosen to efficiently excite fluorescence in the substance of which the particles under investigation are composed, and the energy of the other beam to excite fluorescence with low efficiency. After detection of the fluorescent radiation by detectors D1, D2, detector D1 being protected by a filter F 1 from backscattered electrons, the signals produced are passed through amplifiers and pulse height selectors, and scalers, to a timer T 12 for the comparison of the intensities, and on reference to a calibration curve the mean particle size can be obtained. Instead of scintillation counters as in the parent, xenon proportional counters are used as detectors. A particular example mentioned of the use of the method is in determining haematite particles. 3H/Zr and 109 Cd sources which, respectively, efficiently and inefficiently excite fluorescence in the iron, are used. Modifications of the source arrangements that can be used are as in the parent. |
