**3. Simulation results**

**Neutron process Energy Geant4 model Dataset**

incident neutrons mimicking the natural sea-level neutron background.

G4NeutronHPElastic G4LElastic

For each semiconductor target, a simulation run consists in the generation of 100 millions (10<sup>8</sup>

of primary incident neutrons on a 20-μm-thick material layer perpendicular to its surface (1 cm<sup>2</sup>

G4NeutronHPInelastic G4BinaryCascade

G4LENeutronInelastic QGSP

atmosphere is at the origin of atmospheric showers that produce secondary particles down to the sea level. After muons, the next most abundant secondary particles at the sea level are neutrons. High-energy neutrons (typically above 1 MeV) represent by far the main threat to electronics at the ground level because these particles being not charged are very invasive and can penetrate deeply in circuit materials where they can interact with atoms to produce charged

To emulate the atmospheric neutron source, the differential flux of cosmic-ray induced highenergy neutrons measured by Gordon and Goldhagen et al. in Yorktown Heights [7] has been considered as the reference input spectrum [8]. This distribution, shown in **Figure 1**, was imported in the Geant4 general particle source (GPS) library [9] to randomly generate

The neutron interaction databases for the different semiconductor materials listed in **Table 1** have been computed in this work using Geant4 version 4.9.4 patch 01. The list of physical processes employed in simulation is based on the standard package of physics lists QGSP\_ BIC\_HP [10]. Concerning the hadronic interactions, in QGSP group of physics lists, the quark gluon string model is applied for high-energy (above ~12 GeV) interactions of protons, neutrons, pions, kaons, and nuclei. The high-energy interaction creates an excited nucleus, which is passed to the precompound model describing the nuclear de-excitation. Nuclear capture of negative particles is simulated within the chiral invariant phase space (CHIPS) model. QGSP\_BIC\_HP list includes binary cascade for primary protons and neutrons with energies below ~10 GeV and also uses binary light ion cascade for inelastic interaction of ions up to few GeV/nucleons with matter. The complete list of the Geant4 classes that we considered for our

**Table 2.** List of the different Geant4 classes considered in the present simulation flow for the description of neutron-

G4NeutronHPElasticData

)

).

G4NeutronHPInelasticData




G4NeutronHPFission G4LFission G4NeutronHPFissionData

G4NeutronHPCapture G4LCapture G4NeutronHPCaptureData -

*Elastic* < 20 MeV

*Inelastic* < 20 MeV

*Fission* < 20 MeV

*Capture* < 20 MeV

matter interactions.

> 20 MeV

neutron simulations is summarized in **Table 2**.

products (recoil nuclei or secondary ions).

120 Numerical Simulations in Engineering and Science

**2.3. Geant4 options, models, and simulation runs**

> 20 MeV

> 20 MeV

[20 MeV, 10 GeV] [10 GeV, 25 GeV] [12 GeV, 100 TeV]
