Photon production assessment for the MCNP{trademark} data libraries

Abstract

The goal of the Multispectral Neutron Logging project was to estimate minimum detection thresholds for environmental contaminants using nuclear well-logging techniques. The specific method was to identify and quantify contaminants from the discrete photons from thermal neutron capture reactions in the formation. Computer simulations using MCNP4A were used to benchmark the computer code against experimental data, and then to predict minimum detection thresholds for other contaminants. High quality photon-production data for MCNP was required for this project. The goal of this work was to assess photon production at thermal neutron energies. This work was extended to include higher energy neutron reactions, En=1-14 MeV. Additionally, the assessment was expanded to include all nuclides and not only the contaminants of interest. This report documents the results of the assessment, and makes general recommendations for the user. Ultimately, it is the responsibility of all users to ensure that the data they are using is appropriate for their particular application. This assessment process reinforced the need for higher quality photon-production spectra for use in the Multispectral Neutron Logging project, as well as for other applications.MCNP is a trademark of the Regents

Monte Carlo simulations of neutron well-logging in granite and sand to detect water and trichloroethane (TCA)

“…Detection of uniform concentrations of P b is more difficult. We use the 7.38 MeV line for detection [2]. As can be seen in Table 22 much higher concentrations are required for detection as compared to C1.…”