[Mesa-users] The branch ratio of 12C+12C

[Rob Farmer]

Hi,

It depends which nuclear network you are using.

For approx21 nets it can be found in the subroutine rate_c12c12npa in
rates/private/ratelib.f90 (note we don't follow things exactly here anyway
as approx21 only has ne20 as a possible output)

For non-approx nets then we don't use branching ratios and just have a
reaction rate (from REACLIB) for each of the different outcomes.

Rob

On Sun, 4 Sept 2022 at 10:16, 辛文宇 via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi, Pro. Timmes
>
> Thanks for your detailed help with my question.
>
> Here is another question.
> Do you know the default branching ratio of 12C+12C reaction in MESA?
> I give a total reaction rate of 12C+12C, the product of 23Mg, 23Na and
> 20Ne is determined. So MESA has the default ratio of
> 12C+12C=> 23Na+p, 12C+12C=> 23Mg+n, 12C+12C=> 20Ne+alpha
> Right? How much the branching ratio are or where can I find this?
>
> Thanks,
> Wenyu Xin
>
>
> > -----原始邮件-----
> > 发件人: "Francis Timmes" <fxt44 at mac.com>
> > 发送时间: 2022-08-31 23:03:36 (星期三)
> > 收件人: "辛文宇" <wyxin at nao.cas.cn>
> > 抄送: "Frank Timmes" <fxt44 at mac.com>, mesa-users <
> mesa-users at lists.mesastar.org>
> > 主题: Re: [Mesa-users] The Module of Network in MESA
> >
> > hi wenyu,
> >
> > the guidance says
> >
> > % cp $MESA_DIR/net/test/src/sample_net.f90 .
> >
> > take a look at sample_net.f90. lines 293-294 say
> >
> > ! instantaneous net energy generation rate
> >          write(6,24) 'eps_nuc    =',eps_nuc, 'erg/g/sec'
> >
> > one can/should explore if one does not immediately believe this
> comment.
> > for example,
> >
> > % cd $MESA_DIR/net
> > % grep -r "subroutine net_get(" *
> > public/net_lib.f90:      subroutine net_get( &
> >
> > where line 639 of net_lib.f90 repeats the claim
> >
> >         real(dp), intent(out) :: eps_nuc ! ergs/g/s from burning
> after including losses from reaction neutrinos
> >
> > one can/should explore if one remains unconvinced.
> >
> > note that neutrino losses from reaction and thermal sources are
> different.
> >
> > fxt
> >
> >
> >
> >
> > > On Aug 30, 2022, at 6:35 AM, 辛文宇 via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
> > >
> > > Dear MESA-users,
> > >
> > >
> > >
> > > I have compiled the Module of sample_net.f according to the
> illustration
> > >
> > > in
> https://docs.mesastar.org/en/release-r21.12.1/using_mesa/just_a_module.html.
> &gt
> <https://docs.mesastar.org/en/release-r21.12.1/using_mesa/just_a_module.html.&gt>;
> >
> > > With a certian logT, logRho and composition, it can output a
> value of eps_nuc.
> > >
> > > But I am not sure whether this value has subtracted the epsilon
> of neutrino loss,
> > >
> > > or this value is only the epsilon of nuclear reaction?
> > >
> > >
> > >
> > > I want to calculate the ignition line according to each burning
> stage, like pgstar
> > >
> > > TRho profile plot. Such as the ignition of C burning is defined
> as the energy
> > >
> > > generation rate of C burning equals to the energy loss rate by
> neutrinos.
> > >
> > >
> > >
> > > Thanks,
> > >
> > > Wenyu Xin
> > >
> > > _______________________________________________
> > > mesa-users at lists.mesastar.org
> > > https://lists.mesastar.org/mailman/listinfo/mesa-users
> &gt <https://lists.mesastar.org/mailman/listinfo/mesa-users&gt>; >
> </mesa-users at lists.mesastar.org></mesa-users at lists.mesastar.org></
> fxt44 at mac.com></wyxin at nao.cas.cn></fxt44 at mac.com>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
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