Silicon Damage Response Function Derivation and Verification: Assessment of Impact on ASTM Standard E722

Abstract

Unsuccessful attempts by members of the radiation effects community to independently derive the Norgett-Robinson-Torrens (NRT) damage energy factors for silicon in ASTM standard E722-14 led to an investigation of the software coding and data that produced those damage energy factors. The ad hoc collaboration to discover the reason for lack of agreement revealed a coding error and resulted in a report documenting the methodology to produce the response function for the standard. The recommended changes in the NRT damage energy factors for silicon are shown to have significant impact for a narrow energy region of the 1-MeV(Si) equivalent fluence response function. However, when evaluating integral metrics over all neutrons energies in various spectra important to the SNL electronics testing community, the change in the response results in a small decrease in the total 1-MeV(Si) equivalent fluence of ~0.6% compared to the E722-14 response. Response functions based on the newly recommended NRT damage energy factors have been produced and are available for users of both the NuGET and MCNP codes.

Neutron damage induced in cardiovascular implantable electronic devices from a clinical 18 MV photon beam: A Monte Carlo study

“…More specifically, Norgett‐Robinson‐Torrens (NRT) damage energy factors were calculated which are to define the 1‐MeV(Si) equivalent fluence radiation damage metric. Subsequent investigation found a coding error in the determination of these factors and in 2016, the NRT values were updated . These new values are used in MCNPX as free‐field radiation response functions for the 1‐MeV(Si) equivalent neutron fluence .…”

“…In this study, we quantified the relative damage induced in CIEDs for an 18 MV clinical photon beam for varying field sizes. We used MCNPX with well‐established silicon damage response functions and ICRP neutron equivalent dose conversion factors . Particular attention was devoted to the modelling of the Varian 2100C/D linear accelerator to ensure accurate contamination neutron spectra.…”