Testing FLUKA on neutron activation of Si and Ge at nuclear research reactor using gamma spectroscopy

TL;DR

This study evaluates FLUKA's accuracy in predicting neutron activation and gamma spectra of silicon and germanium sensors irradiated at a nuclear reactor, demonstrating its capability with a 13% average uncertainty.

Contribution

It provides the first validation of FLUKA's low energy neutron library and decay photon scoring for semiconductor activation analysis.

Findings

FLUKA predicts gamma peak amplitudes with 13% average uncertainty.

Radionuclide production data agrees with experimental gamma spectra.

The work estimates systematic errors in neutron activation simulations.

Abstract

Samples of two characteristic semiconductor sensor materials, silicon and germanium, have been irradiated with neutrons produced at the RP-10 Nuclear Research Reactor at 4.5 MW. Their radionuclides photon spectra have been measured with high resolution gamma spectroscopy, quantifying four radioisotopes ($^{28}$Al, $^{29}$Al for Si and $^{75}$Ge and $^{77}$Ge for Ge). We have compared the radionuclides production and their emission spectrum data with Monte Carlo simulation results from FLUKA. Thus we have tested FLUKA's low energy neutron library (ENDF/B-VIIR) and decay photon scoring with respect to the activation of these semiconductors. We conclude that FLUKA is capable of predicting relative photon peak amplitudes, with gamma intensities greater than 1%, of produced radionuclides with an average uncertainty of 13%. This work allows us to estimate the corresponding systematic error on neutron activation simulation studies of these sensor materials.