Preliminary Analyses of SWINPC Beryllium Neutron Multiplication Integral Experiments

Neutron multiplication experiments on beryllium are being carried out at the Southwest Institute of Nuclear Physics and Chemistry in the People's Republic of China. The experiment is briefly described. Preliminary analyses of the experiment are performed using ENDF/B-IV, B-V, and B-VI data. Several problems related to the experiment are discussed. The following conclusions regarding the beryllium integral experiment are reached:

1. Beryllium multiplication is sensitive to the ⁹Be(n,2n) secondary spectrum.
2. The Li-glass detector, BF₃ counter, and ²³⁵U fission chamber all give good accuracy in measuring the ¹H(n, γ) reaction rate.
3. Only a 2% difference is found in beryllium multiplications for a bare beryllium system and for a beryllium/polyethylene + water system. The beam duct has little influence (merely 1%) on beryllium multiplication.
4. Preference is given to small detectors to decrease detector perturbation.
5. The calculational uncertainty is expected to be <1%