[mesa-users] ni56 beta decay rate is function of temperature? and goes to 0 for logT < 8?

[Stan Woosley]

Ni56 does not beta decay - ever.
It is a pure electron capture nucleus.

At low T it captures electrons from its bound shells
At high T and high density (> about 10**6), it captures from the Fermi sea

If it were fully ionized and in a vacuum, it would live a long time,
but eventually it would decay by positron emission.


Stan



On Oct 23, 2013, at 12:29 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:

> Hi Josiah,
> 
> So are you saying that fpr Ni56 -> Co56 beta decays really do go away at low T leaving only electron captures?
> Or was I right in reading Stan's email that we are missing a lower bound on beta decays that isn't in the tables?
> 
> -B
> 
> 
> 
> 
> On Oct 23, 2013, at 12:23 PM, Josiah Schwab wrote:
> 
>> Hi Bill,
>> 
>> The tables in your original message were for positron emission.  Here is
>> the Ni-56 -> Co-56 electron capture.
>> 
>> lYeRho             leps-   electron capture;     ni56 co56
>>    1   -8.684   -9.164   -9.291   -9.387   -8.777   -7.439   -6.184   -5.406   -4.325   -2.782   -0.691    2.011
>>    2   -7.705   -8.165   -8.291   -8.387   -8.364   -7.418   -6.182   -5.406   -4.325   -2.782   -0.691    2.011
>>    3   -6.834   -7.171   -7.293   -7.388   -7.417   -7.212   -6.168   -5.403   -4.324   -2.782   -0.691    2.011
>>    4   -6.118   -6.220   -6.310   -6.392   -6.418   -6.393   -6.027   -5.372   -4.319   -2.781   -0.691    2.011
>>    5   -5.384   -5.388   -5.399   -5.421   -5.423   -5.395   -5.305   -5.087   -4.266   -2.773   -0.690    2.011
>>    6   -4.448   -4.447   -4.444   -4.432   -4.403   -4.363   -4.278   -4.170   -3.834   -2.691   -0.682    2.012
>>    7   -3.134   -3.134   -3.132   -3.127   -3.113   -3.091   -3.039   -2.964   -2.727   -2.093   -0.595    2.015
>>    8   -1.311   -1.311   -1.310   -1.305   -1.293   -1.275   -1.232   -1.177   -1.039   -0.719    0.028    2.046
>>    9    1.069    1.069    1.069    1.070    1.071    1.073    1.078    1.085    1.104    1.159    1.386    2.333
>>   10    3.035    3.034    3.034    3.034    3.035    3.035    3.036    3.037    3.040    3.048    3.084    3.420
>>   11    4.825    4.825    4.825    4.825    4.825    4.825    4.826    4.826    4.826    4.827    4.831    4.926
>> 
>> So those captures are moving along at a good clip (makes sense given the q-value).
> 
> 
> 
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