MEASURED CONVERSION EFFICIENCIES OF P45, PARATERPHENYL, TETRAPHENYL BUTADIENE, AND SODIUM-SALICYLATE PHOSPHORS IN THE SOFT-X-RAY WAVELENGTHRANGE

The measured conversion efficiencies at 9.89, 23.6, 44.7, and 160 angs trom of P45 phosphor screens, as well as those of paraterphenyl, tetra phenyl butadiene, and sodium salicylate at 9.89, 44.7, and 67.6 angstr om, are presented. The conversion efficiency is defined as the ratio o f photoelectrons ejected from the photocathode of a visible detector, which are excited by the scintillated photons that are emitted from th e phosphor in a solid angle of 2 pi, to the number of soft-x-ray photo ns incident on the phosphor. The effect of the phosphor's thickness on the conversion efficiency was studied. The P45 phosphor converts the soft-x-ray photon (10-200 angstrom) into an order of magnitude more vi sible photons than the low-Z phosphors. The P45 phosphor screen used i n conjunction with a photomultiplier tube offers a soft-x-ray photodet ector with a conversion efficiency that ranges from 0.5 at 160 angstro m to 12 at 9.89 angstrom and a high electronic.