Ivalue, aluminium alloy

[bourgouina]

In the file: EGSnrc/HEN_HOUSE/pegs4/density_corrections/compounds/aluminumalloy_type6061.density

The I-value is 188.02901 eV while is should be something close to pure aluminum I-value of 166 eV. NIST ESTAR program issue

[ftessier]

This is correct, the ICRU Report 90 clearly states that the mean excitation energy (I-value) of aluminum is one of the best known, an reiterates: I_Al = 166 eV with a standard uncertainty 1.3 eV. Since aluminum type 6061 contains only about 2% impurities (mostly Mg and Si, around Al), it makes sense to use 166 eV as the I-value in aluminumalloy_type6061.density, unless estar can calculate a close value. I will review the other aluminum density correction files and open a pull request to fix this.

[ftessier]

Same argument applies for aluminumalloy_type1100.density. More hesitant with aluminumalloy_type2014.density which has 4% copper. @mainegra estar balks on trying to run with the aluminumoxide1.0gcm3.density data input, are you able to check it at your end? Fortunately, elements/aluminum.density is correct.

[ftessier]

The problem with estar was that I had to input Element symbols as Mg instead of MG (!). I recomputed the aluminum alloy density corrections with estar (icru90 version) and I get I-values very close to pure aluminum (166 eV), which makes more sense.

[ftessier]

Comments continued in pull request #705.