Dear @ceruttif ,
Thank you for your help and it works, by the way I have other question, just see the picture below
The question is at “COMPOUND” card, if I use “$Li”、“$F”、“$Zn”、“$S” instead of specific value, the “Mix” option can not choose “Mass”, could you help me to solve it?
Just add the minus sign to your material fraction values in the respective #define preprocessor directives. This way they will be interpreted by FLUKA as mass fractions (see the manual), independently of the Atom option displayed by Flair, which, as long as a variable is used in a card field, does not know its actual sign.