Results for NIEL in silicon absorber from NJOY 2021 (with ENDEF/B VIII.0 library) and ASTM-E722 versions

On this page, the Silicon damage function reported in ASTM-E722-19 is compared with the previous versions ASTM-E722-14 and ASTM-E722-09. In Table 1 are summarized the ENDF/B cross section library version, displacement threshold energy E_d and NJOY code version employed in each ASTM-E722 standard release. The displacement threshold energy is not defined in ASTM-E722-19.

Table 1. The cross section library, displacement threshold energy E_d and NJOY code version used for calculating the Silicon damage function in ASTM-E722-19, ASTM-E722-14 and ASTM-E722-09. ^natSi is intended as ²⁸Si, ²⁹Si and ³⁰Si in their natural abundance composition

In Figure 1 is shown a comparison of the ASTM-E722 standards. The ASTM-E722-19 has a profound discrepancy with respect to ASTM-E722-14 and ASTM-E722-09 for neutron energies in the range from 10^-6 to 10³ MeV.

Figure 1. Comparison of the silicon damage function D_Si as a function of the neutron energy as reported in ASTM-E722-19 (green solid line), ASTM-E722-14 (red dashed line) and ASTM-E722-09 (blue solid line).

In Figure 2 is shown a comparison of the Silicon damage function of ASTM-E722-19 with respect to the values calculated with NJOY-2021 and ENDF/B.VIII.0 cross section library using a displacement threshold energy Ed=21 eV (data from SR-NIEL–7 web calculator).

Figure  2. Comparison of the silicon damage function D_Si as a function of the neutron energy as reported in ASTM-E722-19 (green solid line) compared to the calculation of NJOY-2021 with ENDF/B.VIII.0 cross section library and E_d = 21 eV.

In Figure 3 is shown the Silicon damage function calculated with different threshold displacement energy E_d using NJOY-2021 and ENDF/B.VIII.0 cross section library (data from SR-NIEL–7  web calculator).

Figure 3. Silicon damage function as a function of neutron energy calculated with Ed in the range 5eV - 50 eV using NJOY-2021 and ENDF/B.VIII.0 cross section library  (data from SR-NIEL–7 web calculator).

In table 2 are reported the values of the NIEL dose in Silicon calculated using the silicon damage function of ASTM-E722-19, ASTM-E722-14 and ASTM-E722-09 divided by the one obtained with NJOY-2021 with ENDF/B.VIII.0 cross section library and displacement threshold energy E_d= 21 eV. The reactor spcetral fluences are those of ITN-ΣΣ (from [Angelescu et al. (1994)]), IPEN/MB-01 (from [Bitelli et al. (2009)]), TRIGA-Vienna (from [Cagnazzo (2014)]), TRIGA ENEA Casaccia and TAPIRO ENEA Casaccia. TRIGA ENEA spectrum is measured at 100 kW in the Lazy Susan channel. TAPIRO ENEA spectrum is measured at 4 kW in the Radial channel 1.

Table 2. NIEL dose in Silicon for different reactor spectral fluence calculated with ASTM-E722-19, ASTM-E722-14 and ASTM-E722-09 divided by the one obtained with NJOY-2021 with ENDF/B.VIII.0 cross section library and displacement threshold energy E_d= 21 eV (data from SR-NIEL–7 web calculator).

References

ASTM E722-19 (2019).

ASTM E722-14 (2014).

ASTM E722-09 (2009).

T. Angelescu et al., Nucl. Instr. and Meth. in Phys. Res., vol. 345, 2, pp. 303-307, 1994

U. Bitelli and F.P. Martins, Brazilian Journal of Physics, vol. 39, pp. 39-43, 2009

M. Cagnazzo et al., 23rd International Conference Nuclear Energy for New Europe, 2014