Читать книгу Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology - Rachel A. Powsner - Страница 25

Strictly speaking, stability is a relative term. We call a nuclide stable when its half‐life is so long as to be practically immeasurable—say greater than 100 years. An isotope of potassium, 40K for example, which makes up about 1% of the potassium found in nature is considered stable but actually has a half‐life of 10⁹ years.

Figure 1.12 Combinations of neutrons and protons that can coexist in a stable nuclear configuration all lie within the gray shaded regions.