Impurities

These commands are new to version 4.01.

Any element that the neutrons can be transported through can be introduced as an impurity into any region in the detector. Each impurity can be switched in and out, and the concentration (number of atoms per unit cm$^{3}$) of each can be set independently of any other.

The commands for switching on the impurities are demonstrated:

[Bank word location] REGION $on(or $off) Z A D(atoms $cm^{-3}$)

• $impurities_global $on (or $off)
• $impurity_1 $D2O $on 11 23 1.0e22
• $impurity_2 $D2O $on 17 00 1.0e22

This example adds NaCl to the D2O region. Note that Cl is specified as natural (Z=17 A=00) because the neutron table for Cl is a natural table.

Placeholders are defined for 10 impurities, but the code can currently support 200 impurities (and this can be increased if required). To add more than 10 impurities an actual set bank command must be used.

Note that because only the neutron code is aware of these impurities, if you introduce sufficient to cause a change in the gamma / photon / electron transport properties the transport of those particles will be wrongly carried out.