Multilevel resonance analysis of sup 59 Co neutron transmission measurements
High-resolution neutron transmission measurements through several thicknesses of {sup 59}Co were performed in 1986 at the Oak Ridge Electron Linear Accelerator (ORELA) in conjunction with the ENDF/B-VI evaluation of {sup 59}Co done at Argonne National Laboratory. These measurements have much better energy resolution than previously published transmission measurements. The results of one of the measurements were used in the ENDF/B-VI evaluation of the total cross section above 100 keV, but the data were not used below 100 keV, but the data were not used below 100 keV, where the ENDF/B-VI cross sections are represented by resolved resonance parameters based on compilation. The ENDF/B-VI resolved resonance parameters were used to compute the transmission for the sample thicknesses used in the ORELA measurements, and large discrepancies were observed between these computations and the results of the measurements. Consequently, all six ORELA transmission measurements were analyzed, in the neutron energy range from 200 eV to 100 keV, using the multilevel R-matrix computer code SAMMY which utilizes Bayes' theorem for the fitting process. The spin J of most resonances and the orbital angular momentum {ell} for the smaller resonances cannot be determined from the data and were assigned somewhat arbitrarily so as to make the s-wave level density proportional to 2J + 1 and to satisfy the Dyson-Metha {Delta}{sub 3} statistics. Calculations with the resonance parameters obtained in the analysis reproduce well the results of the ORELA transmission measurements which were done at 80 m and 200 m with sample thicknesses varying from 0.005 to 0.3 atoms/barn. The transmission measurements are not very sensitive to the values of the resonance capture widths; therefore, the capture widths obtained in this analysis have large uncertainties.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- DNA; USDOE; Defense Nuclear Agency, Washington, DC (USA); USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5697452
- Report Number(s):
- ORNL/TM-11762; ON: DE91012135
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COBALT 59 TARGET
NEUTRON REACTIONS
CAPTURE
CROSS SECTIONS
ENERGY DEPENDENCE
ENERGY RESOLUTION
NEUTRON TRANSPORT
NUCLEAR DATA COLLECTIONS
BARYON REACTIONS
HADRON REACTIONS
NEUTRAL-PARTICLE TRANSPORT
NUCLEAR REACTIONS
NUCLEON REACTIONS
RADIATION TRANSPORT
RESOLUTION
TARGETS
651620* - Nuclear Properties & Reactions
A=59-89
Experimental