Lk. Fifield et al., ACCELERATOR MASS-SPECTROMETRY OF PLUTONIUM ISOTOPES, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 117(3), 1996, pp. 295-303
The feasibility of measuring plutonium isotope ratios by accelerator m
ass spectrometry has been demonstrated. Measurements on a test sample
of known composition and on a blank showed that isotope ratios could b
e determined quantitatively, and that the present limit of detection b
y AMS is similar to 10(6) atoms of plutonium. For Pu-239, this limit i
s at least two orders of magnitude lower than that practicable by alph
a-spectrometry. In addition, Pu-240/Pu-239 ratios were measured for fo
ur samples for which the combined activity of the two isotopes had bee
n determined previously by alpha-counting. All measurements of plutoni
um isotope ratios entailed injection of PuO- into the 14UD accelerator
operating at 3.5 MV, gas stripping, and analysis of the 7(+) charge s
tate after acceleration, Plutonium ions at 28 MeV were detected in a l
ongitudinal-field ionisation chamber with an energy resolution of 3%.
Using uranium oxide as a surrogate for plutonium oxide, it was shown t
hat UO- was the predominant negative ion and that the probability for
its formation and extraction was 0.3%.