[Mesa-users] [EXT] How to check a nuclear reaction rate?

Wed Mar 27 00:44:08 UTC 2024

Hello Eb,

Thanks a lot for this information.

Following the changelog, I suppose if I want to replace the default 14N proton capture rate with the NACRE II value shipped with MESA, I should write:

num_special_rate_factors = 1

reaction_for_special_factor(1) = 'r_n14_pg_o15'

special_rate_factor(1) = 1

filename_of_special_rate(1) = 'r_n14_pg_o15_nacreII.dat'

in my inlists, and run $MESA_DIR/empty_caches before running my models; and if I want to replace multiple rates, I set num_special_rate_factors to the number I want and define other entries in a similar way. Please tell me if this is wrong, thank you.

I have not changed nuclear reaction rates before, so I should have been using the defaults. I used `show_rates` to convert r_n14_pg_o15_1.bin, and the txt file tells me that:

when T8 = 1.0000690699539715E-01, rate = 2.0247671654597788E-022.

However, this is slightly (about 3.3%) below the NACRE rate provided by REACLIB Database

https://reaclib.jinaweb.org/n14(p,g)o15/nacr/

which claims: when T9 = 1.0000690699539715E-02, rate = 2.09489965936E-22.

Could this be due to different forms of fitting functions? Thanks.

Cheers,

Kaili

________________________________
From: Ebraheem Farag <ekfarag at asu.edu>
Sent: Tuesday, March 26, 2024 6:58 PM
To: Cao, Kaili <cao.1191 at buckeyemail.osu.edu>
Cc: Mathieu Renzo <mrenzo at arizona.edu>; mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] [EXT] How to check a nuclear reaction rate?

Hello Kaili and thanks Mathieu, Be careful that you are sure which rate you are reading in. The default n14pg rate in MESA is from NACRE1, and is set in $MESA_DIR/rates/private/raw_rates. f90: 239 case(ir_n14_pg_o15) 240 call do1(rate_n14pg_nacre)The

Hello Kaili and thanks Mathieu,

Be careful that you are sure which rate you are reading in. The default n14pg rate in MESA is from NACRE1, and is set in $MESA_DIR/rates/private/raw_rates.f90<https://urldefense.com/v3/__https://github.com/MESAHub/mesa/blob/5992b8ed6c3033a560ee4361f4cc86335c2bb6f4/rates/private/raw_rates.f90*L239__;Iw!!KGKeukY!zVv5mOzul0tRIDw0i-sHh034ARffwLjtJr6Dx4ry-uN7hRx4Tqorb_93tx9KO1RmpSUQcSGJSwue5kueu_2eyYbXs7cD$>:
239            case(ir_n14_pg_o15)
240               call do1(rate_n14pg_nacre)

The controls for changing which n14_pg rate you adopt have been removed, but you can still adopt the rate by placing it in your local ./rate_tables directory or the global one that lives in $MESA_DIR/data/rates_data/rate_tables. See the changelog for rates in version r22.05.1<https://urldefense.com/v3/__https://docs.mesastar.org/en/release-r24.03.1/changelog.html*id10__;Iw!!KGKeukY!zVv5mOzul0tRIDw0i-sHh034ARffwLjtJr6Dx4ry-uN7hRx4Tqorb_93tx9KO1RmpSUQcSGJSwue5kueu_2eyZmYtvWT$>
which describes all of this in detail.

The default $MESA_DIR/data/rates_data/rate_tables directory also provides the n14_pg rate from cf88 as well as NACREII if you want to give those a try.

Cheers,
EbF

On Tue, Mar 26, 2024 at 2:25 PM Cao, Kaili via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>> wrote:
Dear Mathieu,

Thank you very much for your quick reply! The `show_rates` script is very handy.

For those who are interested, I checked several values and found a slight disagreement between MESA and JINALAB. I will think more about this.

Cheers,
Kaili

________________________________
From: Mathieu Renzo <mrenzo at arizona.edu<mailto:mrenzo at arizona.edu>>
Sent: Tuesday, March 26, 2024 4:47 PM
To: mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org> <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>>
Cc: Cao, Kaili <cao.1191 at buckeyemail.osu.edu<mailto:cao.1191 at buckeyemail.osu.edu>>
Subject: Re: [EXT][Mesa-users] How to check a nuclear reaction rate?

Dear Kaili, there is a way to have MESA print out in a txt file the value of the rate used for a specific reaction as a function of T. This requires using a small script called `show_rates` to convert rates cached in binary format into a human-readable
Dear Kaili,

there is a way to have MESA print out in a txt file the value of the rate used for a specific reaction as a function of T. This requires using a small script called `show_rates` to convert rates cached in binary format into a human-readable format. The script is available in $MESA_DIR/rates/test, see also the relevant section in the documentation<https://urldefense.com/v3/__https://docs.mesastar.org/en/latest/net/nets.html*inspect-the-temperature-dependence-of-used-rates__;Iw!!KGKeukY!0QlmTdnJvC0E1CaZrSUz7TvYvpiV-rjmVoz9yx6tnS8Bq_rNHy-Qb3j8dCKZJbXvYMrjHylRUXvL-uRn3JfLrjyeo4yp7N0$>.

Hope this helps!
Mathieu (with many thanks to Rob Farmer who taught me how to do this)

On 3/26/24 13:41, Cao, Kaili via Mesa-users wrote:

External Email

Dear MESA Users,

Thank you for reading this email.

I would like to ask about how to check a nuclear reaction rate used in MESA, specifically the proton capture rate of 14N, which was halved in 2006 and is important for my purposes.

I understand that the jina_reaclib_filename control is default to "current standard version," but I find the corresponding file (jina_reaclib_results_20171020_default) hard to decipher, and I wish to make a direct comparison to:

https://reaclib.jinaweb.org/n14(p,g)o15/im05/<https://urldefense.com/v3/__https://reaclib.jinaweb.org/n14(p,g)o15/im05/__;!!KGKeukY!0QlmTdnJvC0E1CaZrSUz7TvYvpiV-rjmVoz9yx6tnS8Bq_rNHy-Qb3j8dCKZJbXvYMrjHylRUXvL-uRn3JfLrjyefN_wm2c$>

Can someone please confirm that this rate is up to date, or instruct me how to check it? Thanks a lot.

Best regards,

Kaili Cao

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