The range-energy relation for beta particles up to 3 Mev is given by the
In the above relations, R is expressed in gm/cm² and E in Mev. The calculated
end-point range of a 1 Mev beta spectrum is thus 0.41 gm/cm² which is equivalent
to 0.15 cm of Al.
The percent transmission of the beta particles of Bi210 through a series of Al
absorbers as obtained in our laboratories is tabulated below.a (Maximum energy
of Bi210 [beta] particles - 1.17 Mev.)
Thin wall GM tubes are produced commercially with wall thicknesses of 30 mg/cm²
in Al, glass, or stainless steel, some of which are designed as dipping counters.
For the RaE (Bi210) spectrum this represents about 63% transmission. It thus
seems feasible to design stack and coolant monitors which will be sufficiently
sensitive to beta particles, regardless of the choice of the detecting element.
CC: Reactor Committee
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