Radon in the environment
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	Complications
The detected alpha-particles may originate from several members of the decay chain shown in the Theory section (fig 2.1). They may even originate from the decay of (the daughters from) the radon isotopes 220Rn and 219Rn. For this reason it is important to discriminate between these different alpha-particles via energy-selection, which is hampered by the large tail at the low-energy side of a peak in an alpha-particle spectrum (see fig. 6.1). Figure 6.1: Energy spectrum after 9,2 hours of exposure to a sample of radioactive contaminated sand, originating from a waste dump near a nuclear power plant in former East-Germany. In fig. 6.1 can be seen that the 218Po peak overlaps the tail of the 214Po peak. To obtain the right value for the number of detected alpha-particles from these different two isotopes, one has to correct for this overlapping. Especially when radon isotopes other than 222Rn come into play, it is hard to discriminate between alpha-particles originating from different isotopes. In fig. 6.1, for instance, one can clearly see a tiny peak between the large ones. Interpolation between the known energies of the 218Po and the 214Po peak yields an energy of approximately 6.7 MeV. The isotope 216Po, daughter of 220Rn, may be responsible for this peak. In that case, after several hours there should also emerge another peak at 8.8 MeV, caused by the decay of 212Po from the same decay series. If this peak at 8.8 MeV arises, one also knows that alpha-particles from the decay of 212Bi will be detected. Since these alpha-particles have an energy of 6.1 MeV, the signal will be almost completely overwhelmed by the 218Po peak. It is obvious that thorough analysis is needed when quantitative results are desired.
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