Biomedical Engineering Reference
In-Depth Information
Table 10.3
Reactions for Threshold Activation Detectors of Neutrons
Reaction
Effective Threshold (MeV)
115
In(n,n
)
115m
In
0.5
58
Ni(n,p)
58
Co
1.9
27
Al(n,p)
27
Mg
3.8
56
Fe(n,p)
56
Mn
4.9
59
Co(n,
α
)
56
Mn
5.2
24
Mg(n,p)
24
Na
6.0
197
Au(n,2n)
196
Au
8.6
Fig. 10.47
Bubble detectors before and after exposure to
neutrons. (Courtesy H. Ing, Bubble Technology Industries, Inc.)
of thousands of microscopic droplets of a superheated liquid (Freon-12, for exam-
ple) are dispersed. A liquid that continues to exist as such at temperatures above
its normal boiling point is said to be superheated. Under this condition, a sudden
disturbance in the droplet, such as the passage of a charged particle generated from
a neutron interaction, can produce a boiling, explosive phase transition into a va-
por. Droplets are instantly transformed into small, visible bubbles in the dosimeter.
