REACTION C-13(N,P)B-13 AT 118 MEV

Cross sections at six angles between 0 degrees and 19 degrees in the c enter-of-mass system have been measured for the ground-state transitio n in the reaction C-13(n,p)B-13 at E(n)=118 MeV. The 0 degrees cross s ection gives a value of 186+/-25 MeV fm(3) for the volume integral of the spin-isospin component of the central part of the effective N-N in teraction. The theoretical value is 161 MeV fm(3) at 100 MeV. A distor ted-wave impulse-approximation calculation for the angular distributio n of the ground-state transition, (1/2(-),1/2) to (3/2(-),3/2), compar es well with the measurement. The 0 degrees measurement is compared wi th other (n,p) and (p,n) measurements on Li-6, C-12, and C-13 to test the universal proportionality of these cross sections to the inverse b eta decay. A falloff in the proportionality constant in going to low e nergy is confirmed.