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I Is radioactive decay independent of the environment?

  1. Jun 21, 2016 #1
    Is the rate of radioactive decay fixed or does the environment have any impact eg would the rate of decay be the same in a low or very high gravitational field (in both cases measured from the viewpoint of the radioactive material)?
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  3. Jun 21, 2016 #2


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    In some special cases you can have huge effects. One example is bound ##\beta## decay, where the electron decays into a bound atomic state rather than a free (scattering) state. Of course it can do so only if the corresponding atomic state is not occupied by an electron since electrons are fermions. A famous example is Rh 187 which as a neutral atom decays with a half-life of about ##42 \cdot 10^9 \, \text{y}##, making it apparently to a perfect clock to measure the age of astrophysical objects by measuring the abundance ratio of Rh and Os (it's decay product). However, when the Rh is ionized, then bound-state ##\beta## decay can take place. Then the half-life becomes of the order of ##10 \; \text{y}##, i.e., a 9 orders of magnitude smaller value. In fact the half-life of ionized Rh 187 has been measured at GSI in Darmstadt (Germany) to be ##33 \;\text{y}##. For a very nice review by Fritz Bosch, one of the scientists involved in these measurements, see

  4. Jun 21, 2016 #3


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    Gravity does affect the radioactive 1/2 life in the sense that time appears to "slow down" when enough mass is present.
  5. Jun 21, 2016 #4

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    For example, some nuclei decay by electron capture. If you are looking at fully stripped nuclei (no electrons), these decays don't happen.
  6. Jun 21, 2016 #5


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    Yep, that's a crossing-symmetric reaction to my example of bound ##\beta## decay :-)).
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