a. Conversions are for weapons grade plutonium only, with no americium.
b. Density of soil 1.5 g/cm3.
c. Specific activity (alpha only) 0.075 Ci/g.
d. Contamination of soil is to the depth of 1 cm.
Tables 1. through 6. provide a variety of conversion factors for weapons grade plutonium.
a. The conversion of alpha instrument readings in CPM into quantifiable units is affected by the type of surface and meter efficiency. For accurate conversions, a surface sample from the area measured should be analyzed with laboratory equipment, and the conversion factor for that area computed. Table 2. provides approximate factors for converting alpha readings in CPM into µg/m2 for various surfaces using the equation: µg/m2 - correction factor x CPM.
b. The correction factors consider unit and area conversions, nominal instrument efficiency during field use, and assume a 60‑sq-cm probe area (PAC-1S). Correction factors should be multiplied by four for use with the AN/PDR-56. Tables 3. and 4. were prepared fromtable 1. and the equation in paragraph 2.a. for users of the AN/PDR-56.
*To convert µCi/m2 to Bq/m2, multiply by 3.7 x 104.
