## A toy Monte Carlo criticality code

Here's a quick implementation of a Monte Carlo neutron transport code for calculating the criticality eigenvalue (i.e. \(k_{\mathrm{eff}}\)) for a fissile system (in slab geometry).

This complements other 1D toy codes for radiation transport I've written:
`snes`

, which calculates
\(k_{\mathrm{eff}}\) using the (deterministic) discrete-ordinates method,
and `fcimc`

, an
implicit Monte Carlo thermal
radiation code that models a Marshak wave in an optically thick medium.