| Popis: |
Angular distributions for the /sup 12/C(n,..gamma../sub 0/)/sup 13/C reaction have been measured with neutrons corresponding to excitation energies of 16.0, 19.2, 20.1, 20.8, and 21.8 MeV. Legendre polynomial coefficients have been determined to second order (a/sub 3/ is small). Polarized neutron measurements were obtained at excitation energies of 16.0, 18.6, 19.2, 20.1, 21.0, 21.8, and 22.3 MeV. A structure seen in the coefficient of the Legendre polynomial P/sub 2/ for the /sup 12/C(p, ..gamma../sub 0/)/sup 13/N reaction is also seen in the present data. A secondary doorway state at 20.5 MeV with an apparent width of 0.5 MeV is suggested by previously measured /sup 11/B(d,..gamma../sub 0/)/sup 13/C data. The presence of this state provides an explanation for the energy dependence of the cross section, the a/sub 2/ coefficient, and the analyzing power coefficient b/sub 2/ in the /sup 12/C(n,..gamma../sub 0/)/sup 13/C data. The same model is also able to describe the energy dependence of the cross section and the a/sub 2/ coefficient observed in the /sup 12/C(p,..gamma../sub 0/)/sup 13/N reaction in the region of 16 to 22 MeV. |
