Optimizing Alpha Yield Scoring and Reducing Statistical Error for Low-Energy p-11B Fusion

Physics, Transport and Magnetic Fields
1

Versions

Please provide the used software versions.

FLUKA:4-5.1
Flair:3.4-5.2

Description

Hello FLUKA Experts,

As a Chemical Engineer working on alternative energy research, I am currently modeling proton-boron (p-11B) nuclear fusion targets using FLUKA.

I am simulating a 675 keV monoenergetic proton beam striking a custom B4C-doped polyurethane foam target. My primary goal is to score the Helium-4 (alpha) yield accurately. I have attached my .inp and .flair files for reference.

My Current Setup:

  • Physics: EVAPORAT activated.

  • Biasing: LAM-BIAS applied to the B-FOAM region for protons (to artificially increase the interaction probability of this low cross-section reaction).

  • Scoring: RESNUCLE to evaluate the H4_YIELD The Challenge: Because the p-11B fusion cross-section is extremely narrow (centered around the ~675 keV resonance peak), getting statistically significant alpha yields without running astronomically high numbers of primary histories is challenging.

    My Questions:

    1. LAM-BIAS Tuning: Are there specific recommendations for setting the interaction length reduction factor in LAM-BIAS for such low-energy, highly specific resonance reactions to maximize efficiency without crashing the transport logic?

    2. Alternative Biasing: Besides LAM-BIAS, are there other biasing techniques (e.g., splitting/Russian roulette via BIASING cards) that are generally recommended for scoring extremely rare secondary particles (Alphas) in low-energy scenarios?

    3. Statistical Error: What is the most robust FLUKA methodology to drive down the relative statistical error percentage for the RESNUCLE outputs in this specific cross-section regime?

    Any insights or guidance on improving the scoring efficiency and reducing the statistical uncertainty would be greatly appreciated!

    Best regards, Uftadi Beyazit Gul

Input files

Please upload all

B_doped_foam.flair (145 Bytes) (input file)

boron_doped_foam.inp (2.3 KB)

boron_doped_foam_24_tab.lis (6.0 KB)

boron_doped_foam_24_sum.lis (11.3 KB)

relevant files. (FLUKA input file, Flair project file, user routines, and data files)