[Mesa-users] about the decay rates of al26, al26-1 and al26-2

amber lauer amber.lauer at tunl.duke.edu
Wed Feb 14 16:37:45 EST 2018


I'm currently perusing the files Mesa>star>defaults>star_job.defaults,
Mesa>star>private>adjust_net.f90, and Mesa>star>net.f90. The first thing I
notice is that the distinction between using REACLIB and the rates in the
cited references (termed "weaklib") depends on some combination of  T and
Z, where the switch occurs at the T determined to be ioniziation T. Both of
these can be set by hand. So if you wish to strictly use REACLIB you should
be able to do so by setting these at some sufficiently high value. I
recommend looking at the section in star_job_defaults.

I notice there is also an option to calculate weak rates according to
Schwab 2015, which allows you to calculate the weak rates base on Schwab
2015 (still looking for this reference) which allows you to specify which
levels will be included n the partition function. This may be what you are
looking for in that respect.



On Wed, Feb 14, 2018 at 2:46 PM, amber lauer <amber.lauer at tunl.duke.edu>
wrote:

>
> On Tue, Feb 6, 2018 at 9:31 AM, Ertao Li via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> Dear all,
>>
>> I am trying to do some research about the abundance of Al26 by using the
>> MESA. I have some questions about the decay rates of al26, al26-1 and al26-2,
>> because they confuse me. Can anyone help please?
>>
>> Firstly, I noticed that the decay rates (stored in cache/*.bin) of  al26, al26-1 and al26-2
>> are constant and do come from $MESA/data/rates_data/JINA_reaclib***.
>> But, from the MESA instruction paper  apj 220 (2015) 15, page 32:
>> \8. WEAK REACTIONS
>> \The rates module provides weak reaction rates for
>> \hundreds of isotopes. By default, when atoms are fully ionized,
>> \these rates are based (in order of precedence) on the tabulations
>> \of Langanke & Martínez-Pinedo...
>>
>> What I think is that MESA only creates the decay rates from JINA but
>> doesn't use them, MESA uses the  $MESA/data/rates_data/weakreactions.tables
>> to get the decay rates but doesn't save them.  Am I correct?
>>
>> Hi Ertao, did you ever get a response to this privately? Because I'm
> curious now too. I'm working on models which pull rates from a different,
> unsupported library, and my list includes (in a single list) both regular
> and weak rates. That leads me to believe it might be a similar case to the
> default, which pulls both from REACLIB, and according to this detail you've
> uncovered, probably overrides REACLIB's weak rates from those taken from
> these papers.
>
> Also, does anyone know why these papers, which seem to employ shell model
> calculations, are favored over the accepted REACLIB rates, which do not?
>
> --
> Amber Lauer
> Postdoctoral Researcher
> Triangle University Nuclear Lab
> Duke University
> amber.lauer at tunl.duke.edu <amber.lauer at duke.edu>
>



-- 
Amber Lauer
Postdoctoral Researcher
Triangle University Nuclear Lab
Duke University
amber.lauer at tunl.duke.edu <amber.lauer at duke.edu>
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