| 摘要 |
816,062. Measuring thickness using beta rays. COMMISSARIAT A L'ENERGIE ATOMIQUE. April 9, 1956 [April 12, 1955], No. 10793/56. Class 40 (3) In a method of measuring the thickness of a deposit, the intensity of the radiations in a narrow frequency band including a characteris. tic X-ray resulting from the projection of beta rays on to it is measured. In the embodiment described, see Fig. 1, plate 1 and deposit 2 are mounted in holder 3. Beta rays 7, emanating from a radioactive isotope enclosed in cylinder 5 of material capable of resisting the rays and in protective container 6, irradiate the deposit which emits X-rays 8 detected and amplified by photomultiplier tube 9 which may include a crystal 10 of sodium iodide activated by thallium. Screen 11 prevents retrodiffusion of the deposit and surrounding objects by stopping parasitic beta rays. After amplification in 13 the desired frequencies (energies) are filtered and fed to counter 15 to determine the thickness of the deposit. The spectrum of detected X-rays is plotted by measuring the activity corresponding to each frequency to which filter 14 is tuned; one narrow region of intense activity is then selected by the filter and measured, see Fig. 2, not shown. In cases where the nature of the deposit is known, immediate measurement of thickness can be made. Detailed results of an experimental determination (see Fig. 3, not shown) are given. |
