—wSTCRE~
terpbenyl-activated plastic scintillator.
divider was controlled through a IC3.
The current to the abotomltiplier
The sciotillators were 1 inch in diameter,
with thicknesses of 0.250 inch for Station IK-39, and 0.050 inch for Scacions
Tr3, K-55, ant MSO.
(See Figs. 1.1 and 1.2 for station locaticus.)
actisa
of the circuit (Fig. 4.10) is such that the current through the 104 is mazximm
with no excitation of the photocathode.
creasing signal.?
The U4 current decreases with in-
Volcage deweloped across a resistor in the plate circuit of
the 10% is used to drive a subcarrier oscillator.
A plot of the ratio of output woltage to no-signal wolrage wersus light~
energy input is linear on log-log paper ower four orders of magnitude in energy
input.
The DASA cobale 60 source at Sandia vas ased to calibrate these instrusents.
Typical calibration data are shown in Fig. &.11.
to data obtained from the cobalt 60 source.
The plotted points correspond
[Extrapolation to higher dose rates
is juscified by the fact thac the instrument is Linear to wv, = 0.32 vheo excited with a calibrated pulsed-light source.
At the two highest stations on both Teak and Orange the dose rate was
expected to be high enough for selenium photovolraic cells to monitor the
light produced in a sodium iodide crystal.
Transducers for these stations
were l-inch cubes of sodium iodide with a photovoltaic cell optically coupled
to each face vith silicone fluid.
The assembly was hermetically sealed in a
thin alumimo case by the Harshsw Chemical Company of Cleveland.
The series
woltage generated by the phocowolraic cells was used to drive a subcarrier
oscillacor directly.
These units were calibrated with a kilocurie cobalt 60
source at Sandia Laboratory.
Typical calibration data are shown in Fig. &.12.
Total gacmm-dose transducers were included in the pose cones at Stations
209 ard 252 on Teak and 1252 and 1158 on Orange.
These transducers consisted
of glass, which darkens under gamma radiatiou (Corning #9762), placed betveen
a tungsten Light source aod a seleniua photocell.
The decrease in photocell
output is then a weasure of the gaa dose seen by the by the glass.
Calibra-
tion was accomplished by insertion of glass which had been exposed to known
xmounts of cobalt 60 radiation.
Seainal calibration data are shown in Fig. %.13.
Im addition to telemetered instrimentation, passive elemeots, including
fila badges and chemical dye dosimecers, were installed for evaluation after
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