Automatic Gamma Spectrometry System
The automatic gamma spectrometry system is housed inside an air-conditioned housing with an internal dimension of 2.8m x 2.6m x 2.3m.
A rotating circular filter drum collects the airborne particulates. The air from the outside is sucked through an air inlet tubing to the circular filter drum depositing the air particulates onto the filter tape. After passing through the circular filter drum, a portion of the air will go via a secondary tubing to reach the charcoal cartridge for iodine collection before being discharged.
A plastic scintillator on top of the circular filter drum measures the gross alpha and gross beta activities of the airborne particulates. Since natural radon contributes significantly to these gross counts, the system will subtract this radon component by means of pseudocoincident technique to obtain the artificial alpha and artificial beta activities of the samples.
At the centre of the circular filter drum, an electro-mechanically cooled high purity germanium detector performs nuclide specific gamma spectrometry analysis on the airborne particulates. The activities of different nuclides are routinely monitored. A sodium iodide detector measures the iodine-131 concentration in the charcoal cartridge samples.