The Model 334AB-G (a replacement for the Model 334AB) is a lightweight, battery-powered, alpha-beta air monitor that can be used as a portable workplace monitor or a portable CAM (continuous air monitor) for emergency-response assessments. Its design provides workers with an early warning of an airborne release of alpha- or beta-emitting particulates. The instrument can monitor up to two alpha isotopes of interest simultaneously with beta monitoring.
The Model 334AB-G has an internal 7-LPM pump. (An external pump with a higher flow rate is available as an option.) The integrated LCD and touchscreen displays information on instrument status and readings during operation. The estimated dose of the isotope(s) of interest and the instrument status are displayed at all times. A visual/audio alarm stack also indicates instrument status. An ion-implanted silicon detector and 1024-channel multi-channel analyzer feed data to the embedded processor board to perform beta detection and alpha spectral analysis for radon background compensation.
State-of-the-art alpha peak fitting quantifies the alpha and beta counts from radon and thoron progeny. This technique uses the profiles of multiple alpha isotope peaks to create a composite curve which best fits the actual alpha spectrum. Because the individual radon peaks are independently determined, the beta background compensation is impervious to radon equilibrium changes and contributes to low probability of false alarms.
An internal guard detector provides real-time beta compensation for changing gamma background levels. An adjustable gamma subtraction factor allows for correction of slight differences in beta and guard count rate in a fixed gamma field to produce proper energy response.
The Model 334AB-G’s sensitivity varies primarily as a function of the window time. The longer Chronic Window has improved sensitivities over the shorter Acute Window time. Sensitivity is reported in Minimum Detectable Concentration (MDC) in Bq/m3 (DAC) and Minimum Detectable Dose (MDD) in Bq-h/m3 (DAC-h).
Sampling Head and Flow
Beta Data Analysis
Alpha Data Analysis
Operation
Physical
