Cross Sections for Pickup Reactions of 14-Mev Neutrons withN14

Abstract

The absolute differential cross sections for the reactions ${\mathrm{N}}^{14}(n, d){\mathrm{C}}^{13}$ and ${\mathrm{N}}^{14}(n, d){\mathrm{C}}^{13*}$ (3.68 Mev) were measured with 14-Mev neutrons at seven laboratory angles from 0° to 65°. The deuterons were detected with a coincidence-telescope spectrometer consisting of two proportional counters and a thin CsI(Tl) scintillator. The angular distributions are both fitted with Butler-type curves for angular momentum transfers of one in agreement with positive parity and spin one for the ground state of ${\mathrm{N}}^{14}$. The reduced width for the ground state transition agrees with that for the reaction ${\mathrm{N}}^{14}(p, d){\mathrm{N}}^{13}$ as required by charge symmetry of nuclear forces. The ratio of the reduced width for the ground state transition to that for the excited state transition rules out the possibility that the ${\mathrm{N}}^{14}$ ground state be a pure ${}_{}{}^3{}_{}{}^{}D_1^{}{}_{}{}^{}$ state. No yield was observed corresponding to the 3.09-Mev and 3.89-Mev states of ${\mathrm{C}}^{13}$.