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The
IC-18 is a three terminal 0.1cc cylindrical ionization chamber.
It is available in 2 different wall materials; tissue equivalent
plastic and graphite. 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 it is possible
to measure mixed fields and separate the gamma and neutron components.
The cylindrical 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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| Model
Number |
Chamber
Volume |
Wall
Material |
Wall
Thickness |
Wall
Density |
| IC-18 |
0.1 CC |
Tissue
Equivalent |
0.064 |
185 mg/cm2 |
| IC-18G |
0.1 CC |
Graphite |
0.064 |
300 mg/cm2 |
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Specifications
 Ionization
Chamber: Cylindrical collecting volume; guarded three-terminal design;
Tissue Equivalent plastic or graphite wall and collecting electrode;
mounted on a 10.5-inch (26.7 cm) long aluminum stem; built in gas
flow provision is optional
Wall Materials:
Graphite, high purity, r =1.80 g/cm3, A-150 tissue equivalent plastic
Signal Connector:
BNC, mates with UG26OB/U or equivalent
Signal Output
IC18: 2.7 x10E10 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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Ordering Information
See model
numbers in table above. Add additional options below. All ionization
chambers are supplied with storage box.
-GF: with
gas flow provision
-WH: with
waterproof housing
-BC: with
TE buildup cap
Consult
factory for other wall materials.
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