DESIGN STUDIES DIRECTED TOWARD A SELF-NULLING BALANCED-CHAMBER ION-CURRENT INSTRUMENT
A self-nulling circuit incorporating balanced ionization chambers constitutes a measuring system in which the output is largely independent of electrical circuit parameters. Both experimental and theoretical analyses indicate, however, that the feasibility of a wide-range survey instrument of this type is severely limited when a conventional electrometer d-c amplifier is employed. It is shown that stability at high dose rates is incompatible with an acceptably rapid low-dose-rate time response. An auxiliary circuit is described which resolves the difficulty by providing transient negative feedback to the floating-grid electrometer input. The feedback path involves current, rather than voltage, feedback and is completed through the measuring ionization chamber by virtue of the non-zero slope of the chamber voltage plateau. An experimental model of the instrument exhibited stability throughout a range of nearly five decades. (auth)
- Research Organization:
- Rochester, N.Y. Univ. Atomic Energy Project
- NSA Number:
- NSA-13-012595
- OSTI ID:
- 4241035
- Report Number(s):
- UR-525
- Country of Publication:
- United States
- Language:
- English
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