77
5
)
10
(
)
10
(
5
1
*
*
i
i
H
H
(3.1)
3.2.4.3.2 Place the УПГД-3Б carriage holder with the device in
the position, where gamma radiation DER from the
137
Cs source is
)
10
(
0
*
H
=(10.0
0.1) µSv/h. After the device has been exposed to
radiation, wait for 5 s and proceed to take five measurements of
gamma radiation DER with a 10 s interval. Enter the results in the
report. Calculate the average value of gamma radiation DER
(
)
10
(
*
H
) by the formula (3.1). The value of gamma radiation
DER with gamma background DER in УПГД-3Б
)
10
(
*
H
, µSv/h, is
calculated as follows:
)
10
(
)
10
(
)
10
(
*
*
*
Ф
H
H
H
,
(3.2)
where
)
10
(
*
H
- is an average value of the device readings
from the source and gamma background in УПГД-3Б calculated by
the formula (3.1), µSv/h;
)
10
(
*
Ф
H
- is an average value of the device’s readings during
gamma background measurement in УПГД-3Б, µSv/h.
3.2.4.3.3 Determine the main relative permissible error of gamma
radiation DER measurement in percentage by the following method.
3.2.4.3.3.1 Calculate the confidence limit of relative random error
of measurement results as follows:
S
t
,
(3.3)
where
t
= 2.78 - a Student's coefficient at the confidence
probability
Р
= 0.95 and
n
= 5;