Beta-gamma systems, background

LB-a/p-CS Low background alpha/beta counting system (analytical device) LEG Low-energy germanium (gamma detector) (analytical device)... 

The radiation type guides selection of the detection system and sample size, which in turn affect the magnitude of the radiation background and the detection limit, as discussed in Section 8.2. The gas-filled proportional and liquid scintillation (LS) counter respond efficiently to alpha and beta particles. Low-energy X rays can also be detected in them, while energetic gamma rays pass through with little interaction. Thin silicon diodes respond efficiently to alpha particles and low-... 

On the other hand, the effect of ambient radiation on the background of the measurement set-up must be reduced. This is effected by way of anticoincidence systems to eliminate the effect of cosmic radiation, lead shields to attenuate the ambient gamma radiation, and extensive use of electrolytic copper with a particularly low radioactivity level as detector material. Nowadays, beta background rates considerably below 10 pulses per minute are achieved with modern low-level systems employing 200 mm dishes. 

In the irradiation of Tc with thermal neutrons, the short-lived (15.8 s) Tc isotope is produced and can be detected by either gamma spectrometry or a low-background beta counter. Analysis can be performed only with a last sample transfer system. Both pre- and... 

---