N14(n,d)C13,N14(n,t)C12, andN15(n,d)C14nearEn=14MeV

Abstract

A triple-coincidence counter telescope consisting of two thin silicon surface-barrier $\frac{\mathrm{dE}}{\mathrm{dx}}$ detectors (114 μ total thickness) and a CsI $E$ detector was used with a pulse-multiplier particle-discrimination system to detect the charged particles emanating from nuclear reactions induced by 14.1- or 14.8-MeV neutrons. Angular distributions of the outgoing charged particles from the ground-state transitions of ${\mathrm{N}}^{14}\mathrm{}(n,d)\mathrm{}{\mathrm{C}}^{13}$ and ${\mathrm{N}}^{14}\mathrm{}(n,t)\mathrm{}{\mathrm{C}}^{12}$ were measured out to a center-of-mass angle of 100° for 14.1-MeV incident neutrons. The ($n,d$) distribution was fitted with two $l=1\mathrm{}$ theoretical curves calculated from the Butler and distorted-wave Born-approximation (DWBA) theories. The ($n,t$) results were fitted by two $l=2\mathrm{}$ curves calculated from the double-stripping theory of Newns and the diffraction theory of Dar, and were compared to previous results obtained for ${\mathrm{C}}^{12}({\mathrm{He}}^3,p){\mathrm{N}}^{14}$. Charged particles corresponding to the excited-state transitions ${\mathrm{N}}^{14}\mathrm{}(n,d)\mathrm{}{\mathrm{C}}^{13} (E_x=3.68\mathrm{} \mathrm{MeV})$ and ${\mathrm{N}}^{14}\mathrm{}(n,t)\mathrm{}{\mathrm{C}}^{12} (E_x=4.43\mathrm{} \mathrm{MeV})$ were detected at forward angles. Angular distributions for the ${\mathrm{N}}^{15}\mathrm{}(n,d)\mathrm{}{\mathrm{C}}^{14} (E_x=0)$ reaction were measured out to 60 degrees for $E_n=14.1\mathrm{} \mathrm{and} 14.8$ MeV. The 14.8-MeV data were fitted with Butler and DWBA curves for $l=1\mathrm{}$, but the 14.1-MeV data were inconsistent with a pure-direct-reaction interpretation. The results agree with previous measurements on the inverse ${\mathrm{C}}^{14}\mathrm{}(d,n)\mathrm{}{\mathrm{N}}^{15}$ reaction, and indicate that a compound-nucleus mechanism contributes strongly near 14.9 MeV of excitation in the ${\mathrm{N}}^{16}$ compound nucleus. Absolute reduced widths ${\theta }^2$ and spectroscopic factors $C^{2}S$ were extracted from the fits to the ${\mathrm{N}}^{14,15}\mathrm{}(n,d)\mathrm{} (E_x=0)$ reactions.