What is the energy distribution of a default fixed source

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1

Hi all,

I am simulating a fuel assembly for a detector simulation. I did not specify any energy distribution or no monoenergetic parameter. So, is the default distribution a Watt distribution? Does the code below ensures that (from source.cpp)?

 // Determine external source energy distribution
    if (check_for_node(node, "energy")) {
      pugi::xml_node node_dist = node.child("energy");
      energy_ = distribution_from_xml(node_dist);
    } else {
      // Default to a Watt spectrum with parameters 0.988 MeV and 2.249 MeV^-1
      energy_ = UPtrDist {new Watt(0.988e6, 2.249e-6)};
    }

I am preparing a document so the knowledge is needed, thank you for your guidance!

Have a nice day.

2

Yes, it is clear in the documentation:

By default, if no energy distribution is specified, a Watt fission spectrum with
a = 0.988 MeV and b = 2.249 MeV-1 is used.