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.
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
Graphite, high purity, r =1.80 g/cm3, A-150 tissue equivalent plastic
BNC, mates with UG26OB/U or equivalent
IC18: 2.7 x10E10 R/coul for air with Cs137
Typically 5 x 10E-15 A when low noise coax is used (measured without
Efficiency: 99% for 3x10E5 R/h @ 250V, 99% for 7x10E5 R/h @ 300V
Signal Cable: Low noise coaxial, e.g., MALCO 250-3834-0000
Requirements: Positive or negative polarity, 250 to 500 V depending
on source strength. Shell is at high voltage potential.
Connector: MHV, mates with UG 932 A/U or equivalent; optionally
Cable: RG-59/U or equivalent
and Weight: Length including connectors, 14.0 inches (35.7 cm);
stem is 10.5 inches (26.7 cm) long; weight 94 grams
Furnished: R/coul at Cs137 with air and appropriate gas
Supplied with wooden storage box
numbers in table above. Add additional options below. All ionization
chambers are supplied with storage box.
gas flow provision
TE buildup cap
factory for other wall materials.