tokens: Except in the case specified in requirement 9.5.3b , the proton or neutron contribution to error rate shall be calculated as follows : 1 . Using the integral or differential energy spectra for protons or neutrons specified in the radiation environment specification , obtain : ( a ) the cross - section experimental curve giving saturation , and ( b ) two other cross section / energy points in the following ranges : • For protons , in the energy range 10 MeV - 200 MeV. • For neutrons , from thermal energies to 200 MeV. 2 . Use one of the following formulas to calculate the SEE rates : • From the environment proton or neutron fluxes and SEE cross sections : o From the environment proton or neutron fluxes and SEE cross sections : o By considering the dependence of the angle of incidence , but assuming not azimuth angle dependence : o By simplifying the previous formula , by - defining smax(E ) as the value of s(E , q ) at the angle q where the cross section maximises for that energy , and - If the incident proton or neutron flux is anisotropic ( and therefore can not be approximated to an isotropic flux ) , approximate dF / dE to the angle - averaged incident flux if used in conjunction with the maximum cross section data , smax(E ) . where : dF / dE = differential proton or neutron flux spectrum as a function of energy ; EMin = minimum energy of the differential energy neutron spectrum ; EMax = maximum energy of the differential energy spectrum ; σnucleon(E ) = proton or neutron SEE cross section as a function of energy .