Instrumentation and Methods
A)
Lon Chamber Measurements
All environmental exposure rate measurements were obtained using a Reuter
Stokes environmental radiation monitor model RSS-lLI1L.
The instrument is
designed to measure environmental radiacion as low as 100 .Rad/year.
The
RSS-LLL consists of a spherical high sressure ion chamber filled to 25 atmospheres of argon.
Incident radiation sroduces ion pairs within the active
volume of the chamber which result in a current flow.
The currene flow is
measured by an electrometer and is directly related to the free air exposure
race (1).
The active volume of the stainless steel ionization chamber is known to
+025.
The current produced inthe chamber is a function of incident radiation
from an external field, cosmic tay-resvonse and contamination found in the
stainless steel.
The equation relating instrument response to energy of the
incident radiarcion is:
Rj] = Kj Ij} + Ra + Ke Ic
where
Rj * current produced in the chamber by the incident
gamma field
Kj = proportionality constant stacing the variability of
instrument response to the energy of the incident
gamma field
Ij = intensity of the gamma field in -R/hr
Ra = current produced by activity in the stainless steel
Ke = proportionality constant
Ic = intensity or cosmic rays
for cosmic rays