| 摘要 |
An instrument for selectively detecting alpha particles emitted simultaneously by radium A and radium C' which are derived from radon includes a device for sampling air through a filter which retains the alpha-emitting aerosols, a single detector in which the alpha particles corresponding to the respective energies of the alpha emissions of radium A and of radium C' are selectively detected, and a plurality of collimators placed between the filter and the detector whereby said collimators direct the alpha radiation from the aerosols collected by said filter to said detector. An absorber is disposed between the detector and the collimators. In addition, multiple collimators are provided to achieve improved efficiency of the device. An image analysis system is used to differentiate alpha-emitters of different energies by size.
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