Method and apparatus for monitoring amount of a substance applied to a fabric

A method of determining the amount of a substance containing atoms of a non-radioactive element of atomic number of 11 or greater applied to a fabric matrix which comprises:

• a. providing a source of radiation which emits a single predominant, monoenergetic radiation within the range of from about 12 to about 19 Kev;
• b. providing a charge pulse detector spaced apart from the source and aligned therewith so as to receive radiation therefrom, said detector being sensitive to said radiation and generating a pulse output which varies in amplitude with the energy of said radiation and having a resolution at least as sharp as about 15 percent within the range of from about 12 to about 19 Kev;
• c. positioning said fabric matrix and applied substance between said source and detector whereby a portion of said radiation emitted by said source passes through said fabric matrix and substance into said detector;
• d. providing readout means connected to said detector;
• and
• e. electronically relating said detector output to the amount of substance applied to said fabric matrix and generating a signal in said readout means in response to said relationship.