Does Fluka have variance reduction function for forced collision like in Mcnp or Phits?

Do Fluka have variance reduction function for forced collision like in Mcnp or Phits?
if it has, how shauld i do, thanks!

Dear Li,

In FLUKA these techniques are called biasing techniques. Several are implemented: region importance biasing, interaction/decay length biasing, leading particle biasing, multiplicity tuning, etc. See section 1.4} of the manual for a complete list, section 2.7} for a few navigation warnings,

You can take a look at

for a first operational introduction, and then investigate further the various biasing cards in the manual.



I mean the variance reduction tecnique like below:
The forced collisions are used for improving tally statistics or thin target analysis by enlarging the collision
probabilities. When specified particle comes into a region defined as the forced collision region, the particle is
divided into two particles. One has a weight by (penetration probability) × (its weight), this particle pass through
to the next region. The other has a weight of (1 - penetration probability) × (its weight), and it is forced to collide
with a target in the region. The collision point is randomly determined according to cross sections. Regions and
factors for the forced collisions can be defined in this section. Non-defined regions are set factor zero.

do fluka have the same variance reduction tecnique?

yes, an analogous one that, as one would conclude after reading the documentation indicated above, is activated by the LAM-BIAS card with SDUM blank and WHAT(2) decreasing the inelastic interaction length, i.e. artificially increasing the interaction probability of given particle species in a given (or all) material(s).