# Relationship between Temperature & Half-Life

1. Jan 1, 2004

### Ace Nova

Lets say we have a radioactive element X in a closed environment, if we were to measure the half-life of element X's radioactive decay at:

1) Near absolute zero
2) At room temperature
3) At 1000s of degrees Kelvin

Would there be a change in element X's half-life even if it is minute? And if so which way would it change in relationship to temperature.

2. Jan 1, 2004

### mathman

I suspect there is no change due to temperature. Temperature is a measure of atomic motion, while radioactivity depends on forces inside the nucleus itself.

3. Jan 1, 2004

### Ace Nova

Consider it this way, (probably should have worded this with more SR), I know that Temperature is a measure of Atomic motion. In a higher temperature sample of the same material, atoms are moving around faster than those in a colder one.

Much like we can basically ignore relativity at small velocities and just use newtonian physics, there is still relativistic effects although they are minute. Couldnt relativity's minute effects change the half life minutely as the average velocity of the atoms increase as temperature increase.

4. Jan 1, 2004

### pallidin

This is a great question!
My thoughts: Since the "event" of radioactive decay is directly and immutably associated with changes in nucleonic states and, since, these changes are directly affected by temperature, it seems reasonable that the rate of radioactive decay is lessened in colder environments.
I would be willing to posit that a gram of plutonium would have zero radioactivity in a zero-degree's Kelvin environment.

5. Jan 2, 2004

### mmwave

I don't think temperature has anything to do with the nucleonic states, only the kinetic energy of the electrons in a solid. So temperature should have no effect on halflife. In fact, my nuclear engineering class taught me that pressure, temperature and chemical changes have no effect on the decay of nuclides. The only way to change the half life is to move it at relativistic speeds and then it becomes a matter of which reference frame you measure it in. In fact for the frame at rest with the nuclide there is no change in half life at relativistic speeds.

I really wish there were a way, then we could maybe shorten the time for radioactive waste to decay.

6. Jan 2, 2004

### pallidin

mmwave, thanks for the correction on my post. I was obviously under an erroneous assumption that zero-degrees Kelvin halted ALL atomic activity.
So a proton, for instance, would not break down into its associated quarks in a zero-degree Kelvin environment, if I am understanding this correctly. So, as you said, nucleonic states are not affected.
If I am getting all this, would it be fair to suggest that a zero-degrees Kelvin environment affects electrons ONLY; for example, co-valent boding is no longer possible, the material easily disintegrates, but the individual atoms remain intact, including any radioactive events?
Good lesson for me. Thanks.

7. Jan 2, 2004

### mmwave

Temperature affects only the electrons. This I know. but now you're getting out of my league. If the outermost electrons they form a bond at higher temperatures it's because the bond is a lower energy state than individual atoms. H2 is a lower energy state for 2 H atoms than staying separate for example. Therefore, I would not expect it to dissociate because you cool it down. We need to ask a chemist or low temp physicist though. The superconductors I've played with stay together at liquid nitrogen temperature.

You're welcome. I like to be useful.

8. Jan 2, 2004

### Nereid

Staff Emeritus
If the temperature of the radionuclide were high enough that it became fully ionised, and then even higher so that significant numbers of nuclear reactions were to take place, then the 'half-life' would be different. But then you'd have taken the poor old atom way beyond the regime in which 'half-life' is defined.

Ditto re pressure - when crushed to white dwarf densities, the 'half-life' will surely be different.