A Low Level Environmental Radiation Monitor with High Sensitivity, Stability, and Dynamic Range

An environmental radiation monitor is described which records gamma radiation levels with a logarithmic response over a dynamic range of four decades (.01 mR/hr to 100 mR/hr achievable without range switching). Constant temperature accuracy is greater than ±10% of indicated reading throughout 3.5 decades of the four decade range. A high degree of temperature stability is achieved (error due to temperature change is less than ±20% of reading over an ambient temperature range of -10°C to + 55°C). Solid-state electronic circuitry is utilized exclusively for increased reliability and long term stability.