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Screened Relativistic (SR) Treatment for NIEL Dose

Nuclear and Electronic Stopping Power Calculator

(version 9.0)

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This is the Total NIEL Dose Web application for neutrons.

The following link give access to the Neutrons Total NIEL Dose Calculator code:

- Total NIEL Dose Calculator for Neutrons (registered)

How to use this Total NIEL Dose Calculator for Neutrons

This tool calculates the total dose imparted, given the spectral fluence of neutrons as a function of the energy and the total fluence. Dose are evaluated for some elements and compounds from values obtained with the software NJOY (2016 and 2021 versions) developed by Los Alamos National Laboratory.

The input parameters and options for the tool are described below.
When the input form has been completed, pressing the "CALCULATE" button will start the calculation and open the "Results" page (allow for pop-up in your browser settings).
The result page will be also linked at the bottom of the calculator page.

Input Parameters:

- Partition Function
- Target material (nuclei available are listed at this page)
- Spectral Fluence vs Energy
- Interpolating Method
- Spectrum Parameters.


Partition Function

The selection allows one to specify the analitycal approximation of the partition function used in the NIEL calculation. Registered users can select Robinson or Akkermann approximation. More information is available in the Energy Partition Function page.


Target Material

In this section it is possible to specify the composition of the target material selecting the number of elements in the compound. Nuclei available are listed at this page. The required parameters for each element are:

- Atomic number (Z)/Chemical symbol
- Stoichiometric index or element fraction
- The displacement threshold energy [eV] (some predefined threshold energies, from 5 eV to 50 eV are available).

Experimentally determined Ed values:

  • Ga: 21.5 eV, As: 21.5 eV as reported in [Campesato et al. (2019)] from proton, electron and neutron irradiations of solar cells. In Triple Junction solor cells, in which the dominat damage mechanism is that one due to the GaAs middle junction, a commonly effective value of Ed was 24 eV [Campesato et al. (2018)], [Campesato et al. (2019)].
  • Ge: 40.5 eV as reported in [Campesato et al. (2019)].
  • In: 43 eV, Ga: 21 eV, P: 21 eV as reported in [Campesato et al. (2018)] for In0.49Ga0.51P single junction solar cells irradiated with electrons and protons. In [Campesato et al. (2019)] with electron, proton and neutron irradiation, it was shown that a commonly effective value of Ed=38 eV can be employed in an equivalent way.


Model Selection

Two different models are available for the computation of NIEL values: NJOY 2016 (with ENDF/B.VII.1 cross section library) and NJOY 2021 (with ENDF/B.VIII.0 cross section library). For target elements Ne, Os, Pt, Yb the NJOY 2016 model is available only with the ENDF/B.VIII.0 cross section library.


Spectral Fluence

This section define the points of the spectral fluence as a function of energy.
The input format is one point per line (Energy - Flux , separated by a space or tab); it is also possible to copy and paste values.
The spectral fluence is normalized to the requested fluence value or, as default, to the total fluence obtained from provided spectrum.

Interpolating Method

This section define the interpolating method used to obtain the Spectral fluence at the energy values defined in NJOY code.
It is possible to select Step, Linear o Spline interpolating function.

Spetrum Parameters

This section define the spectrum parameters that are used to obtain the Spectral Dose at the energy values defined in NJOY code.
They are:
- Requested Fluencetotal: Total fluence to which the integral of the neutron spectral fluence is normalized.
- Elow : Lowest energy above which the total fluence is evaluated.
- Emin : Lowest energy from which the NIEL dose calculation is performed.

The spectral Dose is integrated to obtain the total Dose. The integral is performed from Emin and from Elow and the two values are displayed in the result table.
The spectral dose is normalized to the requested fluence value or, as default, to that corresponding to the total fluence obtained from provided spectrum.


The result page contains the input parameters and the results graphs and table.
The graph of the spectral fluence, which contain the input points and the interpolated values, is given.
Also, the graph of the spectral dose as a function of energy is given.
The result table contains the Dose (in [Mev g-1] and [Gy]) calculated with E>Emin and with E>Elow.