| 摘要 |
960,373. X-ray analysis. COMMISSARIAT A L'ENERGIE ATOMIQUE. Sept. 13,1960 [Sept. 15, 1959], No. 31449/60. Addition to 816,062. Heading G1A. The invention relates to a method and apparatus for X-ray analysis of a sample which uses a radio-active beta-ray source to irradiate the sample and a crystal X-ray spectrograph to measure the intensity of a characteristic line in the X-ray spectrum obtained. As shown the sample S is mounted in a holder 3 which may be driven steadily past the investigation position by a motor Ml if so desired. The apparatus may either be used to measure the thickness of a deposit on the face of the sample or the proportion of a given chemical element present. Irradiation is by means of a layer 33 of Promethium 147 deposited on a metal ring 34 and covered with a thin protective film 35 of polyester resin. The ring 34 has a central channel 4a through which passes X-rays from the sample and retro-diffused beta rays. The latter are diflected by permanent magnet 26 to prevent them reaching the X-ray spectrograph. The X-rays pass through parallel receiving slits 38 to a crystal 36 of lithium fluoride mounted on a plate 37 rotatable about the axis O. Rays diffracted by the reticular parallel planes of the crystal are received by a further set of parallel slits 41 on arm 40 adjustable about axis O and those passing through reach proportional counter 17. The high voltage supply for the counter is indicated at 12 and the pulses generated are passed to amplifiers 13a and 13 and then to a device 14 passing pulses corresponding to rays above a given energy level. These are integrated in rate-meter 15a and fed to a recorder 15b. It is preferred to calibrate the apparatus using standard samples. Where it is necessary to determine the amount of an element of low atomic member present it is necessary to enclose the apparatus in a removable chamber V and to evacuate the chamber by means of a pump P. Other possible radio-active sources are Krypton 85 and Strontium 90 and the permanent magnet 26 could be replaced by an electromagnet. The choice of analysing crystal in the spectrograph will depend on the wavelength of the X-ray line under investigation; mica, gypsum, and quartz crystals can be used. Specification 859,153 also is referred to. |
