particle density

in nuclear chemistry
https://doi.org/10.1351/goldbook.P04424
The number of particles (nuclear or elementary) divided by the containing volume.
Source:
PAC, 1982, 54, 1533. 'Glossary of terms used in nuclear analytical chemistry (Provisional)' on page 1547 (https://doi.org/10.1351/pac198254081533)