Displacement Damage Calculator

Neutron displacement damage with ASTM E722-19 and DT/DD fusion presets. Proton displacement damage for space radiation environments. See also: Fluence to Dose — rad(Si) | Stopping Power & LET

Neutron Displacement Damage

Calculate 1 MeV neutron equivalent fluence using ASTM E722-19 silicon displacement kerma.

Neutron Source

Neutron Energy (MeV)

Neutron Fluence (n/cm²)

Neutron κ_D,Si(E) data: Full 360-bin ASTM E722-19 Table A1.1. R(E) = κ(E)/95 where 95 ± 4 MeV·mb is the reference 1 MeV neutron value. Energy range: 0.175 keV – 19.95 MeV.

Proton Displacement Damage — Space Radiation

Convert monoenergetic proton fluence to displacement damage dose. Proton displacement damage is the primary concern for space electronics exposed to trapped proton belts (Van Allen), solar particle events, and galactic cosmic ray protons.

Proton Energy (MeV)

Proton Fluence (p/cm²)

Proton NIEL data: SR-NIEL Calculator v11.0 (Boschini et al.), E_d = 21 eV, Hadron+Coulomb model. Energy range: 0.1 MeV – 10 GeV.

Pre-characterized — Direct Entry

Already have a 1 MeV neutron equivalent fluence or DDD value from a previous analysis?

1 MeV Equivalent Fluence (n/cm²)

How It Works

Displacement damage occurs when incident particles knock silicon atoms out of their lattice positions, creating vacancy-interstitial pairs (Frenkel defects). These defects degrade minority carrier lifetime, reduce gain in bipolar transistors, and increase dark current in photodetectors and CCDs.

Neutron displacement damage:

The ASTM E722-19 standard defines the silicon displacement kerma function κ_D,Si(E), which characterizes neutron displacement damage as a function of energy. The damage equivalence factor R(E) = κ(E)/95 normalizes to the 1 MeV reference value of 95 ± 4 MeV·mb. This calculator embeds the full 360-bin ASTM E722-19 Table A1.1. Individual bins show fluctuations due to nuclear resonance structure (especially 50–200 keV and above 3 MeV); these average out when integrating over a spectrum. Preset energies for DT fusion (14.1 MeV, R ≈ 1.9) and DD fusion (2.45 MeV, R ≈ 0.7) are provided for direct use.

1 MeV neutron equivalent fluence:

                        Φeq [1 MeV n/cm²] = Φ × R(E)
                    

Proton displacement damage:

Proton displacement damage is quantified using NIEL (non-ionizing energy loss) — the energy deposited into atomic displacements per unit path length. NIEL includes contributions from Coulomb elastic scattering and nuclear reactions, corrected by the Lindhard partition function. In space radiation environments — trapped proton belts, solar particle events (SPE), and galactic cosmic ray (GCR) protons — displacement damage is the dominant degradation mechanism for bipolar and optoelectronic devices.

Results are expressed as 10 MeV proton equivalent fluence, using NIEL_p(10 MeV) = 9.40×10⁻³ MeV·cm²/g as the reference. The displacement damage equivalence factor (DDEF) = NIEL_p(E)/NIEL_p(10 MeV).

Note: The NIEL hypothesis assumes displacement damage scales linearly with NIEL. While a useful engineering approximation, deviations can occur for heavily ionizing particles or at very low energies where defect cluster morphology differs.

Displacement damage dose (D_d):

                        Neutron: Dd = Φeq × NIELn(1 MeV)   where NIELn(1 MeV) = 2.037×10−3 MeV·cm²/g

                        Proton: Dd = Φ × NIELp(E)

Most sensitive devices:

Bipolar transistors, optocouplers, photodetectors, solar cells, and CCDs are the most displacement-damage-sensitive electronics. CMOS logic is generally tolerant because it does not depend on minority carrier lifetime. See our Radiation Effects resource for tolerance tables.

References

ASTM International, “ASTM E722-19: Standard Practice for Characterizing Neutron Energy Fluence Spectra in Terms of an Equivalent Monoenergetic Neutron Fluence for Radiation-Hardness Testing of Electronics.”
P. J. Griffin, “Impact of ASTM Standard E722 Update on Radiation Damage Metrics,” Sandia National Laboratories, SAND2014-5005, 2014.
M. J. Boschini et al., “SR-NIEL Calculator: Screened Relativistic (Nuclear and Electronic) Stopping Powers and Range Tables, with Application to Space Radiation,” sr-niel.org, v11.0.
G. P. Summers et al., “Damage Correlations in Semiconductors Exposed to Gamma, Electron and Proton Radiations,” IEEE Trans. Nucl. Sci., vol. 40, no. 6, pp. 1372–1379, 1993.
C. J. Dale et al., “A Comparison of Monte Carlo and Analytic Treatments of Displacement Damage in Si Microvolumes,” IEEE Trans. Nucl. Sci., vol. 41, no. 6, pp. 1974–1983, 1994.
S. R. Messenger et al., “Nonionizing Energy Loss (NIEL) for Heavy Ions,” IEEE Trans. Nucl. Sci., vol. 46, no. 6, pp. 1595–1602, 1999.
I. Jun et al., “Proton Nonionizing Energy Loss (NIEL) for Device Applications,” IEEE Trans. Nucl. Sci., vol. 50, no. 6, pp. 1924–1928, 2003. (Historical reference — proton NIEL data superseded by SR-NIEL calculations.)