Tritium Air Monitor: High performance portable survey monitor SENSITIVITY The 400SBDγC is useful for measurements as low as 2 μCi/m3 . The new OTC electrometer, which measures to below 10-16 amperes combines low noise and high zero stability. Unlike other instruments, the 400 series instruments no longer require a front panel manual zero control. Thermally induced zero shifts of the electrometer and associated electronics have been eliminated. Tritium Air Monitor: Model 400SBDγC RADON INTERFERENCE, NOISE RESPONSE For an unambiguous measurement of very low tritium a monitor must be able to ignore response to ambient radon. The 400SB series incorporates this capability and therefore produces accurate, fast and drift free measurements to nearly +1 μCi/m3 . TOTAL GAMMA COMPENSATION Cruciform ionization chamber geometry provides nearly perfect gamma compensation regardless of photon energy, flux gradient or flux direction. Gamma compensation of the 400 series ins