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Nuclear Talent
Course 7
NT4A

bbnex

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# TALENT

## Training in Advanced Low Energy Nuclear Theory: EXERCISES

### Reaction Network Exercises

(Pre-Course Assignment)

Download, compile and run the Big Bang Nucleosynthesis Code

1. Compile the code with your fortran90 compiler.
2. Report in the Reaction Network Code discussion thread your success with machine information.
3. Generate light element abundance predictions for a range of initial baryon-to-photon ratios, $\eta$.
• Create the “Schramm Plot”
4. Generate light element abundance predicions for a range of $\eta$, with $N_\nu = 4$ and $5$.

(During-Course Assignment)

Run a reaction network with given nuclear input for:

1. Fixed temperature and density
• Try various temperatures and densities
• Try different network sizes
• Swap out a reaction rate with a different version
• Vary initial composition (X, Y, Z or Ye)
• Let evolve until Nuclear Statistical Equilibrium is reached
2. Temperature/density trajectories
• $T(t) = T(0)\exp{(-t/\tau)}$
• or $T(t) = \frac{T(0)}{(1+t/(n\tau))^n}$
• $\rho (t) = \rho (0) [1.+f_{\nu}(T(t))](T(t)/T(0))^3$
• How do initial conditions affect the resulting nucleosynthesis
• How does the trajectory form affect the results?

## Big Bang Nucleosynthesis Exercises Discussion

, 2014/05/15 11:32

Successfully downloaded, compiled (gfortran public_bigbang.f90 -o public_bigbang.exe) and ran code. Takes maybe 5 minutes to complete on my mac so Schramm plot will take a while … probably need to modify code to run in a script via command line without keyboard input. Somebody wants to do that?

, 2014/05/19 04:21

Compiled and ran on Mac OS X 10.9.2 with gfortran 4.9.0. For those still trying to run a range of eta conveniently, the functionality is already built into the code. You just need to uncomment some of the lines in public_bigbang.f90 between 48 and 119.

, 2014/05/19 11:01

Compiled and ran successfully on Mint 16 and gfortran version 4.8.1. Takes rather long (~30min) on my laptop. However the ratio for Li7 and H is way too low in my calculation even if I run it for 1d12 seconds. Can anyone confirm this? I suspect that maybe the Be7 decay is not inclulded. Using the abundances of Be7+Li7, the ratio seems reasonable.

, 2014/05/21 18:31

Heiko, my calculation also gave a way too low Lithium-7 to proton ratio, when compared with the Schramm plot above.

, 2014/05/19 18:09

Compiled and ran on Mac OS X 10.8.5 and gfortran 4.8 It took ~7 mins on it

, 2014/05/20 13:20

Compiled and ran on my Ubuntu 12.10 and gfortran 4.7

, 2014/05/21 18:26

Compiled and ran on MAC OS 10.9.2 and gfortran 4.9.

, 2014/05/22 13:19

Compiled and ran on Mac OSX 10.9 with gfortran 4.9

, 2014/05/23 08:01

For those having issues with how long this code takes, one can edit the file network.dek and change the parameter setting

    integer, parameter :: abignet = 500,

this is the maximum number of isotopes.

Reduce this number and see if you get any better performance.

, 2014/05/23 16:38

After using Richard's fix outlined above, compiled and ran using MinGW with gfortran 4.8.1. Took about 9 min to run with N_nu = 2.

, 2014/05/26 10:43

Compiled and ran just fine on Fedora 20 kernel 3.14.4 with gfortran 4.8.2. (Also tried compiling on a machine with gfortran 4.4 and received lots of compile errors that were fixed using 4.8.2.)

, 2014/05/26 10:46

Linux version 3.7.10-1.28-default, gcc version 4.7.2, ifort Version 11.0. Got very low 7Li abundance.

, 2014/05/27 19:20

Compiled on my Mac OS X 10.7.5 using gfortran 4.8.2. Following the advice from a participant above, I commented out some of the lines in public_bigbang.f90 between 48 and 119. The code has been running a very long time, and I'm not sure if changing the parameter abignet as suggested above will help. Therefore, I haven't been able to reproduce the Schramm plot.

, 2014/05/27 21:37

Compiled and ran on Linux 3.2.0 with gfortran.

, 2014/05/27 21:49

Compiled successfully on Debian 3.2 with gfortran 4.7.

, 2016/05/02 17:34
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bbnex.1399051223.txt.gz · Last modified: 2014/05/02 13:20 by cyburt