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

Biasing
1

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

2

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.

Cheers,

Cesc

3

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?

4

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).