JPS56124074A - Radiation monitor - Google Patents

Abstract

PURPOSE:To make possible an accurate measurement of radiation without depending upon the magnitude of a counter ratio by setting a pulse amplifier which can control a gain by a current flows through a Geiger-Muller (GM) counter. CONSTITUTION:When a radiation is incident on a GM counter 1 to form a current path in the GM counter 1, a current flows in a route of the second resistor 2, the GM counter 1, and the third resistor 11 as a GM current detection circuit which detects the GM current flows in the GM counter 1. As the result, a voltage proportional to the GM current is appeared at both ends of the resistor 11. When the radiation incident on the GM counter 1 increases, the GM current also increases, thereby increasing the voltages of both ends of the third resistor 11. In this case, the decrease of the value of a wave crest of the pulse signal appears at the negative side of a capacitor 5 is corrected by increasing the gain of a pulse amplifier 6 detecting the increase of the GM current. Thus, the value of an output wave crest of a gain automatic controlling pulse amplifier block 13 becomes always constant and the accurate measurement is possible.