[Mesa-users] custom rates

amber lauer amber.lauer at tunl.duke.edu
Mon Feb 19 10:49:36 EST 2018


Great, thanks. This helps a bunch.

On Sat, Feb 17, 2018 at 12:23 PM, Josiah Schwab <jwschwab at ucsc.edu> wrote:

> Hi Amber,
>
> > ​For weak rates, I see that according to file in the method is similar
> > to the combination of rate_list.txt and rate files, but the weak rate
> > files are expected to be in hdf5(hdfs?) rather than .txt format?
>
> When you're in the regime that the weak rates are non-trivially density
> and temperature dependent (see Zach's email from earlier in the week),
> you need to provide several 1D & 2D tables per reaction.  To save the
> user the hassle of formatting a text file, we use hdf5 for this.  The
> custom_rates test suite case has an example python script that shows how
> to populate an appropriate hdf5 file.
>
> > ​Also for weak rates, I see that there is also the file ​weak_info.list
> > which contains slightly different info, the half life and the quantity
> Qneu
> > (the neutrino energy?). Can someone talk about the difference between
> that
> > file (other than the obvious) and the weak rates tables (similar in
> format
> > to weakreactions.tables)?
>
> weak_info.list is primarily used to set the rate at low temperature (see
> rates_initialize.f90, and also Zach's email).
>
> If you are doing work that requires low-T weak rates, it is worth being
> a little careful here and double checking that the values for your
> reactions of interest are what you think they should be.  The transition
> between the tables and low-T (REACLIB/terrestrial) rates is something
> that could use some restructuring; it is often confusing.  Physically,
> this is a bit of a tough spot because we're going from the tables (which
> assume complete ionization) and moving to rates for neutral-ish atoms.
>
> Most problems can safely ignore this sort of thing, but for an example
> of a case where one needs to be a little more careful, see
>
>   Shen, K. J. and Schwab, J. (2017)
>   Wait for It: Post-supernova Winds Driven by Delayed Radioactive Decays
>   https://urldefense.proofpoint.com/v2/url?u=http-3A__adsabs.
> harvard.edu_abs_2017ApJ...834..180S&d=DwIFaQ&c=
> imBPVzF25OnBgGmVOlcsiEgHoG1i6YHLR0Sj_gZ4adc&r=IZ3U2LUL6yhDK-
> Uf8F_eU9W85o61MM43boq-nVwHt38&m=TvljOlQnee6eaahfavXO_
> Lp2hIs05QHv_aPGh1-JN3s&s=3boxCW385FcCPQdY-bWLypaU8RCpL7uwmZyfd3WqSEY&e=
>
> where Section 3 explains some of the rates gymnastics we undertook.
>
> > Also, the info in weakreactions.tables appears to conform to the same
> > data set as described in weak_rate_list.txt, but is not, to my
> > knowledge, in hdf5 format.
>
> Yes, when I added the ability to specify custom weak rates I left the
> existing master weakreactions.tables in its plain text format.  There
> was no reason to change something that was working.
>
> New reaction rates (i.e. the Suzuki 2016 rates) that have been added
> since are in the hdf5 format.
>
> Hope that helps,
> Josiah
>



-- 
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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