| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a highly reliable radioactive gas monitor having improved noise resistance. <P>SOLUTION: In the radioactive gas monitor, a semiconductor sensor 21 and a preamplifier 22 are shielded by double electromagnetic shields composed of an inside electromagnetic shield 23 and an outside electromagnetic shield 24, and an air hole 233 is disposed on an inside incoming radiation film 232. Thereby, even if a deflection is formed in an outside incoming radiation film 242, the distance between the inside incoming radiation film 232 and the semiconductor sensor 21 is not changed and the change in the stray capacitance between the distance can be controlled. Therefore the inflow of the noise to the semiconductor sensor 21 caused by the pulsation of a sample gas can be prevented. Further, by one point grounding these double electromagnetic shield together with the outer shield 33 of a composite cable 300 via 0V of a power unit 52 by a grounding line 56 of the measurement part, and by separately grounding a sample container 1 and a shielding body 3 with a grounding line 5 of a detection part, inflow of the external noise via the ground can be prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
