|MadSci Network: Physics|
Generally, the answer is no; it is not possible to stop radioactive decay. This is because radioactive decay occurs only when it is energetically favorable and requires no outside input of energy. There is one type of radioactive decay, electron capture decay, where it is possible to slow down the rate of decay. Electron capture decay occurs when an orbital electron is captured by the nucleus resulting in the effective change of a proton to a neutron. This reduces the Atomic Number by 1 but does not affect the atomic mass. Because it is possible to change the amount of energy required to remove an electron, it is possible to affect the probability of the electron being captured. The largest difference observed was between an electron in a metal and a fluoride compound. The difference in the observed half life was approximately 10%. It would have been much greater at zero degrees Kelvin. I have just moved, and my reference books are buried in boxes. If you are interested in reading about the modes of decay and half life, I recommend Nuclear and Radiochemistry by Friedlander, Kennedy, Macias, and Miller.
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