Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK

L A is the air layer in µgcm -2 ;
P is the pressure within the vacuum chamber in Torr
d is the source-detector spacing in cm.
The recoil contamination is one of the main factors affecting the background radioactivity in
the vacuum chamber. Therefore it particularly influences performances of alpha spectrometry
systems in terms of minimum detectable activity. Another factor that plays an important role
specifically for the alpha spectrometry systems is the chemical yield in the preparation and
separation process. A specific guideline gives the suitable expressions for calculating the
MDA [150] but the general considerations previously introduced are still valid.
At the end of the alpha spectrometry measurement, the radionuclide activity in the
sample is calculated using the tracer yield (Y T) given by:
where:
T
Nn is the net area for the peak of tracer alpha;
tM is the measurement time;
εT is the efficiency factor for the tracer;
AT is the tracer activity added at the beginning of the sample manipulation.
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equation 2.4.3
The activity of the radionuclide of interest (A R) in the sample is finally evaluated as
follows:
where:
R
Nn is the net area for the peak of the radionuclide of interest;
tM is the measurement time;
YT is the tracer yield (from equation 2.4.3)
εR is the efficiency factor for the radionuclide of interest.
2.4.2 MATERIALS AND METHODS
2.4.2.1 Description of the devices
A R = N n
R
t Mε RY T
YT = N T
n
tMε T AT equation 2.4.4
The urine samples were collected in a vial 2 litres volume. The feces were collected in
two vials: the first used just as transport container (1 litre volume); It contains the second
smaller vial (0.5 litre volume) with excreta inside. This second vial is ashed together with the
excreta during the chemical preparation of the sample. Samples of 100 millilitre volume were