Partition of the Average Energy Deposited in Silicon as a Function of Incident Neutron Energy

Abstract

The average energy deposited in crystalline germanium per incident neutron has been calculated as a function of neutron energy. The calculations are for neutron energies below 4 MeV, where scattering events predominate and charged-particle production is minimal. A calculation at 14 MeV by Nichols is also included. As the incident neutron energy increases from 50 keV to 14 MeV, the average ionization energy deposited increases from \ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$ to $\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ (erg/g) per (neutron/${\mathrm{cm}}^{2}$), and the energy available for displacements (nonionization) increases from $\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ to $\ensuremath{\approx}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ (erg/g) per (neutron/${\mathrm{cm}}^{2}$). The calculated neutron energy dependence of the energy available for displacements agrees with the energy dependence of carrier-removal experiments in germanium performed with monoenergetic neutrons. Comparisons of these calculations are made with analogous ones for silicon. The energy deposited into atomic processes per carrier removed for \ensuremath{\sim}40-\ensuremath{\Omega} cm $n$-type germanium is $\ensuremath{\approx}0.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ erg/carrier, and the corresponding number is about a factor of 2 larger in the case of $n$-type silicon.