pair attenuation coefficient

in nuclear chemistry
https://doi.org/10.1351/goldbook.P04396
The attenuation coefficient when only the pair production process is taken into account.
Source:
PAC, 1982, 54, 1533. 'Glossary of terms used in nuclear analytical chemistry (Provisional)' on page 1547 (https://doi.org/10.1351/pac198254081533)