Proton Upset Monte Carlo Simulation

The Proton Upset Monte Carlo Simulation (PROPSET) program calculates the frequency of on-orbit upsets in computer chips (for given orbits such as Low Earth Orbit, Lunar Orbit, and the like) from proton bombardment based on the results of heavy ion testing alone. The software simulates the bombardment of modern microelectronic components (computer chips) with high-energy (≈200 MeV) protons. The nuclear interaction of the proton with the silicon of the chip is modeled and nuclear fragments from this interaction are tracked using Monte Carlo techniques to produce statistically accurate predictions.

Following the bombardment with high-energy heavy ions (such as carbon, gold, and the like), the upset rate dependency on each of the ion species is known. This precisely defines the amount of energy an ion must deposit within the “sensitive volume” of the chip in order to cause an upset. These data are put through PROPSET, which repeatedly models the proton/silicon collision process and tracks each of these fragments from each collision and the energy that each imparts into the “sensitive volume” of the chip. PROPSET then counts the number of upsets produced by a given number of incident protons.

This innovation allows for the code to be easily modified so that the effect of input parameters, such as the thickness and shape of a computer chip’s sensitive volume, can be assessed. Heavy ion data are easily entered in terms of only four Weibull parameters rather than a data file of 50 to 100 data pairs. In order to determine how to track ions through a chip’s sensitive volume while accounting for the variability of that sensitivity, a grid is defined and works outward where each shell has a different sensitivity. PROPSET executes rapidly on a personal computer.

This program was written by Patrick M. O’Neill and Coy K. Kouba of Johnson Space Center and Charles C. Foster of Foster Consulting Services. MSC-24274-1

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