Mössbauer thickness

in Mössbauer spectroscopy
https://doi.org/10.1351/goldbook.M04034
The effective thickness of a source (\(t_{s}\)) or @A00034@ (\(t_{a}\)) in the optical path.
Source:
PAC, 1976, 45, 211. (Nomenclature and Conventions for Reporting Mössbauer Spectroscopic Data) on page 214 [Terms] [Paper]