An avalanche detector radioisotope X-ray fluorescence analyzer has been developed that has rapidly, accurately, and confidently measured the calcuim and potassium content of U. S. Geological Survey silicate rock standards. The measurements were made at room temperature with percentage errors of +5 percent. The interference due to X-rays from adjacent elements was minimal. The precision of measurement with the solid-state instrument was such that at least 90 to 95 percent of the readings were within l of the mean value. Copyright © 1968 by The Institute of Electrical and Electronics Engineers, Inc.
