“…The reaction C 12 (£,7)N 13 has been studied by Roberts and Heydenburg, 2 C 13 (£,Y)N 14 by Dee,Curran and Petrzilka,3 and N 14 (£,7)0 15 by Curran and Struthers. 4 This letter is a report of the measurement of the last reaction of the cycle; 5 viz., N 15 (p,a)C 12 .…”