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The IC-17
is a three terminal 1cc spherical ionization chamber. It is available
with a wide range of different wall materials including tissue
equivalent plastic, air equivalent plastic, graphite, magnesium,
and polyethylene. These chambers are used for direct comparison
of radiation source strengths, beam monitoring in accelerator
facilities, and accurate measurement of absorbed dose at a prescribed
experimental point. By using a pair with different wall materials,
one hydrogenous and one non hydrogenous, it is possible to measure
mixed fields and separate the gamma and neutron components.
The spherical detector is mounted on the end of a stem with the
signal connections made through a terminal block. The block contains
the BNC signal connector and the MHV high voltage connector. The
stem effects are less than 1 x 10E-12A for a 1 x 10E4 R/h exposure
with Co60. The effect may be minimized by using a + and –
collecting voltage on the detector and averaging the readings.
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Specifications
Ionization Chamber: Spherical collecting volume; guarded three-terminal
design; TE plastic, graphite, magnesium, or conductive polyethylene
wall; collecting electrode same material as wall; mounted on a
10.5-inch (26.7 cm) long aluminum stem; built in gas flow provision
is optional
Wall Materials:
Tissue Equivalent Plastic, r =1.13 g/cm3; Graphite, high purity,
r =1.80 g/cm3; magnesium, high purity, r =1 .74 g/cm3; polyethylene,
-3% added carbon for conductivity, r =1.12 g/cm3
Signal
Connector: BNC, mates with UG26OB/U or equivalent
Signal
Output IC17A: 3.8 x 10E9 R/coul for air with Cs137
Leakage:
Typically 5 x 10E-15 A when low noise coax is used (measured without
collection voltage).
Collection Efficiency: 99% for 3x10E5 R/h @ 250V, 99% for 7x10E5
R/h @ 300V
Recommended
Signal Cable: Low noise coaxial, e.g., MALCO 250-3834-0000
High Voltage
Requirements: Positive or negative polarity, 250 to 500 V depending
on source strength. Shell is at high voltage potential.
High Voltage
Connector: MHV, mates with UG 932 A/U or equivalent; optionally
SHV
High Voltage
Cable: RG-59/U or equivalent
Overall
Size and Weight: Length including connectors, 14.0 inches (35.7
cm); stem is 10.5 inches (26.7 cm) long; weight 94 grams
Calibration
Furnished: R/coul at Cs137 with air and appropriate gas
Accessories:
Supplied with wooden storage box
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