Home > Data Bank > Nuclear Data Services > SAMMY users' group >

Answer:

Abundances are used in calculating sigma [which we will define as the cross section for the material] using the formula

sigma = sum (over all included nuclides) of { [abundance of the nuclide] * [cross section for that nuclide alone] }

The thickness is used in converting from cross section to transmission

transmission = exp { - thickness * sigma }

Normalization and background are applied to whatever-the-final-calculation-is. In other words,

final-theoretical-value = normalization * almost-final-theoretical-value + background

Hence if you are analyzing, for example, fission yield data, then ‘almost-final-theoretical-value' is the fission yield, Doppler- and resolution-broadened and with multiple-scattering corrections added (if requested); normalization & background are applied to that fission yield.

If you are analyzing transmission data, the ‘almost-final-theoretical-value' is transmission (with all the appropriate corrections such as Doppler- and resolution-broadening).

Interchangeability? In the analysis of a measurement of cross section data, with only one nuclide in the sample, normalization and abundance are clearly equivalent and could be interchanged. In all other situations (e.g., measurement of yield rather than cross section), these parameters are likely to be highly correlated but are not interchangeable.

Home - About Us - Work Areas - Data Bank - Publications - Press Room - List of acronyms - Search