May, 1963 where W is the energy (in e.v.) necessary to form an ion or radical pair, and I is the dose rate (in e.v./cm.a/sec.). This formula is essentially the same as eq. 15 of ref. 2a. 3. The value of yo is then calculated by trial and , value of yo is assumed and N(xm) is calcuerror. 4 lated by (9). When the correct value is found, N(x,) = voyoxm. If the trial N is too high, raise yo, and vice versa. We have found that about six trials are necessary; but it is sometimes observed that the second term of (9) IS very insensitive to changes in yo, so that the labor is much redraced. 4. Using the value of yo thus obtained, calculate N and y for vo 5 v
