Comparing modern measurements of the [sup 11]B(d,nγ[sub 15.1])[sup 12]C excitation function with previous values

A possible means of active interrogation of special nuclear materials is detection of signature emissions following induced photofission. This method requires a probe gamma-ray beam to induce the photofission. The B-11(d,n gamma(15.1))C-12 reaction is a candidate for the source of this probe beam. The reaction is prolific and the produced 15.1 MeV gamma-ray is close to a photofission cross-section peak for U-235,U-238 and Pu-238,Pu-239. In order to model an active interrogation system using the B-11(d,n gamma(15.1))C-12 reaction as a source probe an accurate value for its differential cross-section must be included in data libraries. Measurements of the differential cross-section for the B-11(d,n gamma(15.1))C-12 reaction have been carried out with a BGO detector and found to differ from previous measurements reported by Kavanagh (1958) and Kuan (1964). The discrepancy in the measurements may be explained by examining the detector response function used by Kavanagh and presumably Kuan to that modeled with MCNP5. A comparison of the MCNP5 and Kavanagh detector response functions normalized to the 15.1 MeV gamma-ray peak pulse height shows a factor of approximately 1.7 difference in integrated counts. Applying this correction to the differential cross-section previously reported by Kuan brings the values into agreement, within uncertainties, to the more recent measurements. The evaluation of the detector response function for the 15.1 MeV gamma-ray signal in the NaI detector reported by Kavanagh to that modeled by MCNP5 is shown. This result is applied to the comparison of recent measurements on the B-11(d,n gamma(15.1))C-12 reaction differential cross-section to those previously reported.