Polarized neutron capture into C13: Evidence for a secondary doorway state effect
Angular distributions for the C12(n,0)C13 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 (a3 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 P2 for the C12(p,0)N13 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 B11(d,0)C13 data. The presence of this state provides an explanation for the energy dependence of the cross section, the a2 coefficient, and the analyzing power coefficient b2 in the C12(n,0)C13 data. The same model is also able to describe the energy dependence of the cross section and the a2 coefficient observed in the C12(p,0)N13 reaction in the region of 16 to 22 MeV. © 1984 The American Physical Society.
Woodworth, JG; August, RA; Roberson, NR; Tilley, DR; Weller, HR; Jury, JW
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