THE MEASUREMENT OF CARBON-14 AND TRITIUM ACTIVITIES IN GAS-FILLED GEIGER COUNTERS

The construction of Geiger counters and a vacuum system for filling them with C/sup 14/-carbon dioxide or H/sup 3/-hydrogen is described. The counters must be quenched electronically. The effect of the pressure of the filling gas and amabient temperature on the counters was investigated. Likely errors are discussed and are found to be consistent with the experimental reproducibility (about 1%). Samples containing about 4 x 10/sup -/s - c/g carbon and 4 x 10/sup -/s - c/g H/sup 3/ at the standard filling pressure (150 mm Hg) gave count rates equal to background (25 c/min). (auth)