1 - IAEA Nuclear Data Services

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4-.4-.5. Random Digital Word Generator
A unit generating binary coded digital words with up
to 20-bit length, random in distance and address, and
simulating therefore experimental conditions has been
developed for the overall test of digital data handling
equipment. The generated spectrum is equivalent to a
white noise spectrum.
5. Radionuclides
5.1. Standardization
An international BIPM intercomparison of dilution
techniques using Go solutions, in which the CBNM
took part, showed that only an error of about 0.05%
could be attributed to our source preparation, while
no significant error (j> 0.02%) was found on the dilution
of the solutions.
An international intercomparison of threshold detectors
and reactor spectra was organized. About 180 sources
from about 10 different reactors were compared.
The total decay rates were determined by integral
counting with our 3" x 5" NaJ detector, the impurities
by our 1.1 cm^ Ge(Li)-detector. All measurements are
completed, but theucalculation will still require some
time.
24-1
An intercomparison of Am was made using all possible
methods: low geometry, liquid scintillation, 4TT and
4-TTa-Y-coincidence. It showed that Am can be standardized
with.0.1% accuracy, but also that this is a
limit at present, caused by all kinds of noise and
physical second order effects. The latter conclusion
seems to be a rather general result from our recent
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work. This Am solution, the activity of which is
known to better than 0.1%, is also available to other
laboratories, as are several other radioisotopes calibrated
with extreme accuracy before.