7.2  McStas and MCNP(X)

As of McStas 2.1 we provide a a series of mechanisms to interchange simulated events between McStas and MCNP or MCNPX:

1. Typically, the intensity parameters in our McStas source components are derived from MCNP(X) simulations, though parametric fits to MCNPtallies.

2. The PTRAC method to read MCNP(X) events into McStas has been available since McStas 1.10 and is a contribution from Chama Hennane, ENSIMAG and Emmanuel Farhi, ILL.

3. The SSR/SSW method to send events via the MCNP “source surface” mechanism between both codes has been available since McStas 2.0. This work has mainly been done by Esben Klinkby, DTU Nutech, with contributions from Erik Knudsen and Peter Willendrup, both DTU Physics.

4. With access to an MCNP source-code license and a patch developed by Esben Klinkby, DTU Nutech, it is further possible to directly compile and link a McStas instrument with MCNP. The method is however quite speed-limited at present, but we envision releasing an improved version later. If interested, please contact Esben Klinkby directly.

Especially method 3 gives a powerful combination with the scatter logging mechanism discussed in the paper [KKW14], allowing to estimate \(\gamma \) dose-rates in MCNP from neutron intensity lost in neutron optics, i.e. the non-transmitted fraction of the McStas neutron beam (and corresponding intensity/weight). Through the McStas example instruments and also the McStas share at http://mcstas.org/download/share we provide a couple of examples of the use of the scatter logger