Picocurie

picoCurie is a non-SI unit of radioactivity equal to one trillionth of a curie (10^-12 Ci). The symbol is pCi. One curie corresponds to 3.7 × 10^10 nuclear decays per second, so one pCi equals 0.037 decays per second, i.e., 0.037 Bq.

Relation to becquerel: 1 Ci = 3.7 × 10^10 Bq, so 1 pCi = 3.7 × 10^-2 Bq.

Usage: used to express very small activities, especially in environmental samples, medical applications with trace radionuclides, and contamination monitoring. In regulatory and clinical contexts, activity is often reported in pCi/L (air or water) or pCi/g (soil).

Measurement and interpretation: detecting pCi-level activities requires sensitive instrumentation such as liquid scintillation counters or gamma spectrometers; converting to dose requires radionuclide-specific factors and exposure geometry.

History and context: The curie was named for Marie and Pierre Curie; picoCurie as a subdivision is part of conventional units still used in legacy literature and certain industries, though the becquerel is the SI unit for activity.