Program - Brookhaven National Laboratory

sponsored the work presented in this paper.
[1] H. Derrien, G. De Saussure, and R. B. Perez, Nucl. Sci. Eng. 106, 434, 1990; H. Derrien, J. Nucl.
Sci. Technol. 30, 845, 1993. [2] J. A. Harvey et al., Proc. International Conference on Nuclear Data
for Science and Technology, Mito, Japan, May 30-June 3, 1988. [3] H. Derrien, L. C. Leal, and N.
M. Larson, Neutron Resonance Parameters and Covariance Matrix of 239Pu, ORNL/TM-2008/123, Oak
Ridge National Laboratory, Oak Ridge, Tenn., September 2008. [4] D. Bernard et al., “239Pu Nuclear Data
Improvements in Thermal and Epithermal Neutron Ranges,” Proc. International Conference on Nuclear
Data for Science and Technololgy, Nice, France April 22-27, 2007.
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Recent Investigations and Findings about the 2d- and 3d-Neutron Strength Functions
Said F. Mughabghab
National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000, USA
These comprehensive detailed investigations were recently undertaken because of the scarcity of available
data on neutron d-wave strength functions and the desire to obtain much-needed precise quantities. This
information is obtained by the least-squares method by fitting total cross section measurements in the keV
to 3 MeV neutron energy region, which is expressed in terms of the scattering radius, R’, the s-, p-, d-,
f-wave neutron strength functions, neutron penetrabilities and phase shifts. The present results for the
average resonance parameters reveal the following findings:
• The 2d peak is observed for the first time at mass number, A = 51.
• Due to nuclear deformation effects, the 3d peak is depressed producing two maxima, located at A =
152 and 170, with similarity to the s-wave case [1].
• Except for the deformed region, the results of spherical optical model calculations for the d-wave
strength functions well describe the present data for A = 48 - 200.
• The derived R’, s- and p-wave neutron strength functions are in very good agreement with those
derived from the resolved energy region [1].
• However, the d-wave strength functions are generally discrepant with available data compiled in [1].
• Quite a few d-wave data are derived here for the first time.
• A comparison with the very few d-wave data, obtained from the resolved resonances, showed good
agreement.
The methodology and its application to optical model calculations and generation of covariance quantities
with the aid of this model will be discussed. Several examples of least-squares fits to the available data
will be presented and the systematics of the d-wave strength functions will be graphically displayed. In
addition, an explanation for the discrepancies with previous data, which were derived from capture and
total cross section measurements, will be given.
[1] S.F. Mughabghab, Atlas of Neutron Resonances, Elsevier (Holland), 2006.
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