LEAD CARBONATE, A NEW FAST, HEAVY SCINTILLATOR

We describe the scintillation properties of lead carbonate (PbCO3), a newly discovered, heavy (6.6 g/cm3), inorganic scintillator. Its fluorescence decay lifetime, measured with the delayed coincidence method, is described by a sum of three exponentials; 24% of the light is emitted with a 5.6 ± 1 ns time constant, 48% of the light is emitted with a 27 ± 2 ns time constant, and 28% is emitted with a 155 ± 10 ns time constant. The emission spectrum peak is centered at a wavelength of 475 nm, and drops to less than 10% of its peak value at 370 nm and 580 nm. We have been unable to obtain an optical quality crystal of pure PbCO3, but when a 3 mm cube of a cerussite (a naturally occurring mineral form of PbCO3) is excited with 511 keV photons, a photopeak with a 42% full width at half maximum is observed at approximately 9% the light output of a bismuth germanate (BGO) crystal with similar geometry. The light output increases rapidly with decreasing temperature, plateauing at twice the light output of BGO at approximately −40° C. Lead hydroxide (Pb(OH)2) can be mixed with PbCO3 in a 1:2 ratio without significantly affecting the scintillation properties. The short fluorescence lifetime, high density, and reasonable light output of this new scintillator suggest that it would be useful for applications where high counting rates, good stopping power, and nanosecond timing are important, such as medical imaging and nuclear science. Copyright © 1990 by The Institute of Electrical and Electronics Engineers, Inc.