Title: Ion Chamber for High-range Gamma Measurement in Space Critical Applications
Authors: Alex, Mary; Prasad, K R
Abstract: An ion chamber for space critical applications
is developed indigenously for high-range gamma radiation measurement. The device
can be used to monitor gamma exposure rates above 1000 R/h for monitoring dose rate
due to irradiated samples in radioactive hot cell facilities, and coolant activity
monitoring in power reactors. The chamber has an overall diam of 27 mm and 53 mm
length. Nickel-plating technique has been used to convert one of the surfaces
of an alumina insulator into an electrode. In size the chamber is comparable to
a GM counter and its performance, radiation tolerance, operational life and long-term
stability
are found to be superior. Tests at BARC show
that the chamber can measure gamma radiation up to 104R/h. It has a gamma
sensitivity of 9 pA/R/h and requires 1000 V to achieve saturation at 9600 R/h. The
chamber response is uniform with in ±3 per cent over gamma energy range between
660 keV to 1.25 meV and compares well with that of a standard Victoreen ion
chamber. The cost of this indigenously developed device is far less than that of
GM counters or imported ion chambers and it has an operational life of 20 y.
Page(s): 35-39
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