说明AEC-71-9071 OPTO-ELECTONIC FEEDBACK. . . The detector assembly shown in this photo is part of an opto-electronic system developed at the Lawrence Radiation Laboratory, Berkeley, in which light-coupling replaces a feedback resistor and which has greatly improved the energy resolution of X-ray fluorescence spectrometers. It is now possible to measure, with precision, many chemical elements of low atomic weight (as light as neon, and perhaps as light as nitrogen). The sample to be tested is placed close to a radioactive source. The radiation absorbed by the sample causes emission of X-rays whose energies are characteristic of the chemical elements present in the sample. The apparatus then displays the cumulative results as energy spectrum - - a graph shows what the sample is made of. Credit: Lawrence Radiation Laboratory, Berkeley
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