DESIGN STUDIES DIRECTED TOWARD A SELF-NULLING BALANCED-CHAMBER ION-CURRENT INSTRUMENT

Technical Report · Tue Apr 01 04:00:00 EST 1958

OSTI ID:4241035

Anderson, L L

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

Related Subjects

AMPLIFIERS
CONTROL SYSTEMS
ELECTRIC POTENTIAL
ELECTROMETERS
INSTRUMENTS
IONIZATION CHAMBERS
PLANNING
RADIATION DOSES
STABILITY