| 摘要 |
PURPOSE:To reduce the cost and improve the accuracy of measurement, by using a device of a proportional counter tube as an X-ray detector, by detecting characteristic X-rays radiated from X-ray-excited targets by means of a monitoring detector, by calculating the amount of said X-rays, by delivering a signal to a collimator controller so as to adjust the amount of exciting X-rays, and by maintaining thereby the amount of the characteristic X-rays at a prescribed value. CONSTITUTION:An X-ray detector 116 of a proportional counter tube is inexpensive, since it necessitates no cooling by liquid nitrogen. Characteristic X-rays radiated from niobium 108 are detected by a monitoring detector 125, and a detection signal thereof is counted by a scaler 130 and stored in a storage circuit 131. The same detection as described above is performed also with respect to molybdenum 109, and a counted value obtained at this time is compared with the counted value stored in said storage circuit 131 by means of a comparator circuit 132. Based on this comparison, a control signal is delivered to a collimator controller 133 so as to adjust the dimensions of the slit 113C of an automatic collimator 113, and thereby the amount of exciting X-rays radiated from an X- ray tube 112 is maintained at a prescribed value. |
