Nesaraja, CD; Brune, CR; Crowley, BT; Kelley, JH; Nelson, SO; Prior, RM; Sabourov, K; Tilley, DR; Tonchev, A; Weller, HR, *Ratio of S factors for (p,gamma) reactions on C-12 and C-13 at astrophysically relevant energies*,
Physical Review C - Nuclear Physics, vol. 64 no. 6
(December, 2001),
pp. 658041-658047 [doi] .
**Abstract:**

*We present measurements of the 12 C(p, γ 0 ) 13 N/ 13 C(p, γ 0 ) 14 N S factor ratio at E p =160 keV. The overall result of 0.33±0.03 is in good agreement with the value of this ratio obtained from previous experimental values of the S factors for the 12 C(p, γ 0 ) 13 N and the 13 C(p, γ 0 ) 14 N reactions. A value for the total S factor ratio of S[ 12 C(p, γ total )]/S[ 13 C(p, γ total )] = 0.24±0.03 is computed by correcting the 13 C(p, γ 0 ) S factor for transitions to the other intermediate states. The direct + resonance model calculation of this ratio and the impact on the CNO cycle are also explored.*