Abstract
In the measurement of cosmic rays on board aeroplanes, it is essentially important to provide suitable devices. A portable Si ionization chamber fulfill the demand because it is cheap, compact and easy to handle. Another type of candidate, a wristwatch type detector with a GM tube, appeared very recently. Its performances are rather poor than the Si type, especially for short distance flights, but are satisfactory when it flies over long distances like Narita-Paris. Correlation coefficient between the GM- and Si-detector is as good as 0.999 in such long distance flights. The shortest flight for safe usage of the GM-detector would be at least 4,000km, which is like Narita-Bangkok. [J Radiat Res 44:417 (2003)]
