# Why doesn't Rubidium decay to Strontium?

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1. May 15, 2015

### unscientific

Both $^{87}_{37}Rb$ and $^{87}_{38}Sr$ are odd-even nuclei, so we can ignore the pairing term $\delta$. I tried to calculate the most stable Z for a given A by finding $\frac{\partial B}{\partial Z} = 0$. That gives the most Z-stable value of $Z_0 = \frac{2\gamma A}{4\gamma + \epsilon A^{\frac{2}{3}}}$ which is $38$ for $A=87$.

If that's the case, then why wouldn't Rb beta decay to Strontium as these are naturally occurring isobars.

2. May 15, 2015

### Staff: Mentor

87Rb does, in fact, beta-decay with a half-life of about 4.8 x 1010 years. See e.g. http://www.nndc.bnl.gov/chart/

3. May 15, 2015

### unscientific

Then why is it so stable with such a long half-life?

4. May 15, 2015

Staff Emeritus
What do you think it's half life should be?

5. May 15, 2015

### unscientific

My question is since it is more stable to undergo beta decay, why doesn't it undergo decay quicker? For example uranium 235's half life is 10 times shorter.

6. May 15, 2015