Gamma-ray absorption measurements have been made using a NaI energy selective scintillation counter with radioactive source gamma-rays of 0.411, 0.664, 1.33, and 2.62 Mev energy. A range of absorbers from hydrogen to uranium was used. The final absorption coefficient was determined to ±0.2 percent rootmean-square statistical accuracy. Additional absorption measurements were made with nuclear reaction gamma-rays at the energies 4.47, 6.13, and 17.6 Mev with the same absorbers. A statistical accuracy of ±2 percent was attained. A comparison of theory to experiment is presented and no radical differences are observed.

• Received 17 December 1951

DOI:https://doi.org/10.1103/PhysRev.87.592