Instrumentation and Methods
A)
lon Chamber Measurements
All environmental exposure cate measurements were obtained using a Reuter
Stokes anvironmencal radiation monitor model RSS-111.
The tnscrumene ts
designed to neasure environmental radiation as low as 100 uwRad/year.
The
RSS<11l consists of a spherical high pressure ion chamber filled to 25 atmospheres of azgon.
Incident radiation produces {on pairs within the active
volume of che chamber which result in a current flow.
The current flow is
measured by an electrometer and is directly related to the free air exposure
trace (1).
The active volume of the stainless steel fonization chamber is known to
+01%.
The current produced inthe chamber is a function of incident radiarion
from am external field, cosmic ray-response and contamination found in the
stainless steel.
The equation relating instrumenc response to energy of the
incident radiation is:
Rj = K} Tj + Ra + Ke Te
where
R4 =™ current produced in the chamber by che incident
gamma field
x} =* proportionality constant scating the variability of
instrument response to the energy af che incident
gamma field
Ij = intenstty of the gamma field in -R/hr
Ry = current sroduced by activity in che stainless steel
Ke ™ proportionalicy constane for cosmic rays
Ic ™ intensity of cosmic rays