Doza MKS-15D Snegir Manual do utilizador - Página 16
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4.5.4 Determination of basic relative measurement error of AED of photon radiation
Determination of the basic relative measurement error of AED shall be performed with one
value of AED equal to 100 μSv.
Perform calibration as follows:
1) Place the dosimeter on calibration installation with rear panel towards the source; the center
of dosimeter's sensitive area (upper rear part of the dosimeter at depth 10 mm) shall be located at the
central axis of the gamma radiation beam at a distance from the source for which the AEDR value is
within the measurement range stated in 1.2.2;
2) turn the dosimeter according to 2.3.1;
3) start exposing the dosimeter to radiation and turn on the stopwatch simultaneously;
4) stop exposure at the AED value of 100 μSv and take readings from the display window
"AEDR" when the statistical uncertainty is less than 5 %.
5) perform no less than three measurements for this test point; calculate the arithmetic mean of
the measured values;
6) calculate the basic relative error in per cent by the following formula
*
where
H is the arithmetic mean of three AED measurements in the test point, μSv;
ср
*
H
t
is the reference value of AED, μSv;
o
t is the duration of exposure, hours.
The results of calibration are considered satisfactory if the relative measurement error of AED
of photon radiation does not exceed the limits stated in the section 1.2.3.
4.5.5 Determination of basic relative measurement error of beta radiation flux density
Determine the basic relative measurement error of beta radiation flux density at values of flux
density 400 and 1000 cm
Perform calibration as follows:
1) turn the dosimeter on according to 2.3.1;
2) perform the background measurement with the detector window closed by the shutter;
3) open the shutter pushing the control lever to the lower extreme position "γ";
4) place the dosimeter with an open detector window above the surface of the source for 2 mm
so that all the work surface of the detector is located over the active surface of the source;
5) take readings from the display window "β [cm
6) perform at least five measurements of beta radiation flux density for each test point,
calculate the arithmetic mean value for each test point;
7) for each test point calculate the basic relative error of beta radiation flux density in per
cent by the following formula
where
P is the arithmetic mean value of beta radiation flux density,·cm
i
P is the value of beta radiation flux density reproduced by the reference source, cm
ref
The result of calibration is considered satisfactory if none of the calculated relative
measurement error of beta radiation flux density exceeds the limit stated in the section 1.2.8.
1
1 ,
-2
-1
·min
.
P
i
i
FVKM.412152.005RE
*
*
Н
H
t
mean
o
100
*
H
t
o
-2
-1
×min
]" on the indicator;
P
ref
100
,
P
ref
16
2
2
CAL
-2
-1
·min
;
(4.3)
(4.3)
-2
-1
·min
.