THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

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TAIIT.E VI-31. Techniques for Measuring Alpha Radioactivity.
Method Application Advantages Disadvantages
A, Total Alpha Activity
1, Air ionization chamber Total assay - survey Simple, easily repaired
instruments. and cleaned, reliable,
inexpensive.
2. Free-electron-gas ionization Total assay.
chamber (A, A-C02, He, N2, etc. )
3. Alpha proportional counter
4. Scintillation alpha counter
5. Low-geometry counters
6. Nuclear Emulsions
Total assay.
Total assay.
Total assay.
Total assay.
Sharp pulses permit high
count rates and tolerance
to ~ activity. Not microphonics.
Reliable and
stable. A known relatively
unchanging geometry,
High signal -to-noisd ratio,
good j3 discrimination.
Not at all microphonics.
Very low background.
Can count sources of
greater activity. Counting
rate not so sensitive
to sample thickness.
Reproducible and reliable.
No low-angle back scattering
correction.
Great sensitivity and
stability. Very simple
apparatus.
Long decay time of pulse
makes inherently wide
pulses - limited to low
counting rates. Low
tolerance to ~ activity.
Signal-to-noise inferior
to proportional counters,
therefore more prone to
spurious counts. Must be
corrected for low-angle
back scattering.
Count rate sensitive to
applied voltage. Requires
pure gas for stability.
Difficult to maintain
stability for long periods.
Lower tolerance to O
radiation than ionization
chamber or proportional
counter. Greater sensitivity
to sample size, and
position.
Not suitable for low activity.
Sensitivity to sample position
and area.
Limited accuracy, considerable
technique required in exposing
and developing emulsions.
Counting tracks is time consuming
and tcdimls.