計数管のend effect

抄録

With a cylindrical flow counter which served as a proportional counter or a Geiger counter by the use of PR gas or Q gas, the end effect on the counting rate is rate is examined by applying collimated Cs¹³⁷ γ-rays lengthwise along the counter tube. The anode wire had a guard tube at each end. The following results are obtained.
(1) Sharp increases in counting rate are observed at both ends of the counter and at the ends of the guard tubes where the anode wire becomes bare. This is attributed to emerging photo and Compton electrons.
(2) In the central portion of the counter, the counting rate with PR gas is higher by about 10 percent than with Q gas.
(3) With the γ-ray applied at the central portion of the counter, good plateau curves are obtained, but near the ends, the rate is seen increasing rapidly as the anode voltage is raised.