[mesa-users] Changing nuclear reaction rates

[Francis Timmes]

dear reggie and ondrea,

the mesa summer schools are a solid resource to help raise your game.

for an explicit, step-by-step, tutorial on changing a reaction rate, 
see ed brown’s 2013 mesa summer school material:

1) http://mesastar.org/teaching-materials

2) download the 2013 mesa summer school zip file.

3) after unpacking the zip file
% cd 2013_summer_school/ed_brown

4) open lab_instructions-2.pdf
instructions start on page 2

of course mesa has evolved a bit since 2013, so some of the 
paths may have changed. for example, the online manual says files 
can be put in the directory is data/rates_data/rates 
but in version 7385 the structure is data/rates_data/rate_tables .

of course you should be creating a work directory per best practices
http://mesa.sourceforge.net/starting.html
when you start changing things and running.

fxt







> On Feb 13, 2015, at 2:14 PM, Ondrea Clarkson <ond20id at gmail.com> wrote:
> 
> Hello everyone!
> I am trying to figure out if I have any options when it comes to changing reaction rates. I am aware as per NET_NOTES  that I can add a file to /rate_tables of my temperature and desired rate. I am a little nervous about this in that I am not sure exactly how MESA handles this file and would like to maximize my accuracy. i.e. how many data points does MESA need here?
> What I had originally wanted to do was to hard code the rate. I had been told that MESA would likely be set up like Tycho in this respect but the more I look into it the more I doubt this. If I understand it correctly, most rates are taken from the binary files in the cache folder and those which are not are in ratelib.f. Is it possible for me to remove a binary file and add my rate parameters to ratelib.f? Any advice or ideas would be greatly appreciated! Thank you!
> 
> Ondrea
> 


> On Feb 12, 2015, at 12:36 PM, Reggie Caginalp <reggiecaginalp at gmail.com> wrote:
> 
> Dear MESA users,
> 
> I am trying to change the reaction rates for the 12C(alpha,gamma)16O reaction. According to the following email:
> 
> http://sourceforge.net/p/mesa/mailman/mesa-users/thread/1381946912314.31814.unist@unist.ac.kr/
> 
> it should be possible to add custom reaction rates by creating a table of (T8, reaction rate) values and adding a line like 
> 
> r_c12_ag_o16             'adopted_rates.txt'
> 
> to data/rates_data/rate_tables/rate_list.txt. Doing ./mk and ./rn in rates/test returns the values of the reaction rates I wrote in the table. 
> 
> However, when I evolve a zahb model, with these reaction rates (which, as doing ./rn in the rates/test folder without the custom table indicates, are roughly the same as the default values in the relevant temperature range), the central O mass fraction stays at roughly its initial value. Running the model without the custom table results in the O fraction increasing to ~0.4, as expected.
> 
> I've attached the O fraction from the runs with the custom and MESA default rates, the table I used for the rates, the inlist (it's the one from the 1M_pre_ms_to_wd test suite example) and the initial model. 
> 
> Any ideas on what the problem may be?
> 
> Thanks so much!
> 
> Sincerely,
> Reggie Caginalp