ABSORPTION OF PHOTONS IN THE REGION FROM 10-20 Mev MEASURED IN P$sup 31$ AND Pr$sup 14$$sup 1$

The total absorption coefficient for photons in P/sup 31/ and Pr/sup 141/ was measured using threshold detectors. The experimental and theoretical results were compared graphrcally. For P/sup 31/ the experimental and theoretical cross sections at 11.0 and 16.5 Mev coincide, but for 19.5 Mev the experimental cross section is larger. The discrepancy is attributed to nuclear absorption. For Pr/sup 141/ the experimental absorption coefficient coincides with the electron absorption coefficient at 11.2 Mev. But at 14.6, 16.6, and 19.6 Mev, the measured absorption coefficient is larger than the electron cross section. (J.S.R.)