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Abstract:
The numerous absolute measurements of the dose constant of radium in equilibrium with its decay products show large variations and ranges of error. A new measurement was carried out using two ionization chambers. The dose output of a radiation source (298 mg Ra-El. with 0.5 mm Pt filters) was measured by the Townsend method in a free air space 26 m long, 24 m wide, and 22 m high. The attenuation coefficient of primary gamma radiation in air was first determined. After consideration of all corrections and the contribution of the scattered radiation, a value of 8.13 plus or minus 0.2 r x cm/sup 2/ x hr/sup -//sup 1/ x mg/sup -//sup 1/ was obtained. A calculated value, obtained using the latest absorption cross section and other physical data of 8.30 plus or minus 5% r x cm/sup 2/ x hr/sup -//sup 1/ x mg/sup -//sup 1/ compares favorably with the experimental value.
