Radiation Detectors
RADIATION TYPES
Fast neutrons rapidly degrade in energy by elastic collisions when they interact with low atomic
number materials. As neutrons reach thermal energy, or near thermal energies, the likelihood of
capture increases. In present day reactor facilities the thermalized neutron continues to scatter
elastically with the moderator until it is absorbed by fuel or non-fuel material, or until it leaks
from the core.
Secondary ionization caused by the capture of neutrons is important in the detection of neutrons.
Neutrons will interact with B-10 to produce Li-7 and He-4.
10
1
7
4
B
n Li
He
5e
5
0
3
2
The lithium and alpha particles share the energy and produce "secondary ionizations" which are
easily detectable.
Rev. 0
Page 9
IC-06
