7741

Westinghouse compensated ionization chamber for thermal-neutron measurement in very high gamma fields. Continuously adjustable electrical compensation suppresses gamma response while retaining neutron sensitivity, enabling reactor monitoring over a wide flux range.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized

Sections: 1
Base: -
Socket code: -
Base pins: -
Nominal heater: -

Description

T4 Westinghouse Sheet lof 2 COMPENSATED IONIZATION CHAMBER TYPE 77.1 The 7741 compensated ilonization chamber ig designed to_detect thermal neutrons in the range from 2.5 x 102 to 2.5 x 10 neutrons/cm</second, in the presence of very high gamma radiction fields. The detector is of rugged construction, incorporating a design which allows operation at temperatures up to 500°F. The 7741 incorporates two outstanding design features. The first is the use of a "guard ring" type of construction to minimize reduction in signal currents due to leakage through the insuwlators. The second 1s the provision for continuously variable, electrical compensation. The neutron sensitivity of the chamber is approximately 4 x 10~~14 amperes/neutron/cm?/second. Gamma sensi- tivity is approximately 3 x 10~~ amperes/R/hr when operated uncompensated, but it is reduced to approximately 3 x 10-13 amperes/R/hr in compensated operation, thus extending the operating range two decades. The 7741 is constructed of high p

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: -
Base pins: -
Nominal heater voltage: -
Nominal heater current: -
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

IonizationChamber

X-ray radiationInterelectrode capacitances

No fixed ratings are recorded for this section.

Source-derived physical/electrical section.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

1947 Westinghouse

Published operating points and test conditions from this source.

SECTION 1

IonizationChamber

Other

neutrons in the range from
10
neutrons in the range from 2.5 x 102 to 2.5 x 10 neutrons/cm</second, in
up to
500
up to 500°F.
currents due to leakage through the insuwlators. The second
1
currents due to leakage through the insuwlators. The second 1s the provision for
chamber is approximately
14
chamber is approximately 4 x 10~14 amperes/neutron/cm?/second. Gamma sensi-
tivity is approximately
10
tivity is approximately 3 x 10~ amperes/R/hr when operated uncompensated, but
it is reduced to approximately
-13
it is reduced to approximately 3 x 10-13 amperes/R/hr in compensated operation,
Signal to Case (Minimum) ,
1
Signal to Case (Minimum) , . 1¢I2 Ohms
H.V. to Case (Minimum)
1010
H.V. to Case (Minimum) . 1010 Ohm
Signal to Case (Minimum)
10
Signal to Case (Minimum) . . 10t4 Ohms
Compensating to Case (Minimum)
1012
Compensating to Case (Minimum) . 1012 Ohms
Operating Voltage
800
Operating Voltage . . . . 300 to 800 Vde
Compensating Voltage
80
Compensating Voltage . . . . -10 to =80 Vde
Thermal Neutron Flux Range
10
Thermal Neutron Flux Range . . . 2.5 x 10° to
2.5 x 2020 n/em®/sec
2020
2.5 x 2020 n/em®/sec
Thermal Neutron Sensitivity
14
Thermal Neutron Sensitivity . . 4 x 10~14 amperes/nv
Gamma Sensitivity Uncompensated
-11
Gamma Sensitivity Uncompensated 3 x 10-11 amperes/R/hr

Characteristic

Resistance (
500
Resistance (500°F)s
Resistance (
68
Resistance (68°F):