16 2. Radioactive Decay
Fig. 2.3. A typical energy spectrum of the b−-particles of^32 P.Fig. 2.4. Decay scheme of^131 I. Eighty-one percent of the total^131 I radionuclides
decay by 364-keV g-ray emission. The 8.0-day half-life of^131 I is shown in
parentheses.
(Note: The b+-decay is shown by a two-step right-to-left arrow between the
two states, the electron capture decay by a right-to-left arrow, and the
a-decay by a down arrow). Although it is often said that^131 I emits 364-keV
g-rays, it should be understood that the 364-keV g-ray belongs to^131 Xe as