Minimum Energy in LET Spectra Calculations

You can specify the minimum energy of ions to be included in your LET spectrum. By default, this value is 0.1 MeV/nuc, the lowest energy to which ions are tracked in the TRANS program. This value is appropriate for most SEU applications.

This option of setting other minimum energy values is provided because the standard formalism for calculating SEU rates due to direct ionization ignores ranging-out in the bit's sensitive volume. In some cases, this approximation can significantly overestimate the SEU rate due to low-energy particles.

For example, in a large, thin device like 93L422s, ranging out of alphas below 5 MeV/nuc can lead to more than a factor of 10 overestimate in the SEU rate during solar particle events.

By varying the minimum energy cut, you can explore the magnitude of this effect in your calculations.