Rapid and precise alpha-particle spectrometry for plutonium materials

Preparation of plutonium sources for alpha particle spectrometry is accomplished by extraction into a xylene solution containing 2-thenoyltrifluoroacetone, followed by evaporation of the xylene solution on a microcover glass, which is ignited briefly in a flame. This gives sources which display peak resolutions equivalent to 12 keV fwhm or less, and enables the spectrum to be accumulated with conversion ratios of proportional 35 keV/channel, enabling rapid data recording and processing. Relative precision and accuracies of < 1% in 238Pu/289+240Pu peak ratios can easily be achieved. The problem of minimizing pile-up background in the measurement of parts-per-million quantities of 236Pu in 238Pu can be solved by using quite short pulse widths from the shaping amplifier. This also permits the use of high total count rates to minimize the counting time. (orig.)