Scintillation detectors alpha particle detection

Figure 9.13 Four examples of response functions (a) 5-MeV Alpha particles detected by a silicon surface barrier detector (Chap. 13), or 20-keV X-rays detected by a Si(Li) reactor (Chap. 12). ib) 1-MeV Gamma ray detected by a NaI(Tl) crystal (Chap. 12). (c) 1-MeV Electrons detected by a plastic scintillator (Chap. 13). (

Silver-activated zinc sulfide [ZnS(Ag)] has been used since radioactivity was first measured to detect alpha particles. It is relatively insensitive to electrons and gamma rays because it is not transparent to its own radiation. Radiation interactions within the detector are not recorded only its surface, where alpha particles interact, emits scintillations. The ZnS is doped with silver to shift its scintillations to a longer wavelength for better PMT response. 

Radiation from radioactive sources can be detected and measured in essentially Ihe same way as X-radialioii (Sections l2B-4and 12B-S). Gas-filled chambers, scintillation counters, and semiconductor detectors are all sensitive to alpha and beta particles and to gamma rays because absorption of these particles produces ionization or photoelectrons, which can in turn produce thousands of ion pairs. A detectable electrical pulse is thus produced for each particle reaching the transducer. 

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