Page 40 - bukuneutron

neutron. While thermal neutron will create prompt gamma
during activation upon collision with the materials. In
this regard, additional care is required in designing a
shielding container for Am-Be-241 and Cf-252 neutron
sealed-source. Therefore, lead or tungsten sheets are
required to eliminate gamma radiation induced by neu-
tron from these sealed sources.

For safety, direct neutrons from the sealed source
to the detector should be avoid, only the scattered neu-
tron will allow to reach the detector. The neutron sealed
source container has opening called collimator where
the neutrons are focused and directed to a certain di-
rection of interest. Other direction is shielded so that
non of neutrons are allowed to get out from the con-
tainer except through the opening of collimator only.

Detector contain He3 gas is used for detecting the
scattered neutrons. The detector is place at adjacent
to the neutron sealed source container so that only the
neutron which has been scattered are detected. This
is important to ensure that the detected and recorded
data of scattered neutrons have sufficient statistic with
as low as possible noise. The thickness of shield-
ing and moderator should be optimized, otherwise, the
weight of the gauge become so heavy where as the
thermal neutron to gamma ratio is small.Therefore, weight
of the gauge should be optimized to have large thermal
neutron to gamma ratio.

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