7657

High-temperature guard-ring fission chamber for thermal-neutron detection. Designed for operation to about 500°F, it is ruggedized for severe shock and vibration and provides stable neutron counting across a wide applied-voltage range.

Directly heatedCold cathodeCommon cathodeDissimilarSpecialized

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

Description

Westinghousé 7657 April 1, 1960 HIGH TEMPERATURE GUARD RING FISSION CHAMBER 7657 The 7657 fission chamber is designed to detect thermal neutrons in the range of 1.4 to 1.4 x 109 neutrons/cm2/ second. The detector is extremely rugged in construction designed to pass MIL-S-901 for shock and MIL-5td-167 {Type 1) for vibration. The 7657 isof guard ring construction, a feature which minimizes electrical leakage across the internal insulators, and it may be operated in any position at temperatures up to 500°F. The 7657 is constructed of aluminum, with high purity alumina ceramic insulators throughout, including those used in the type HN coaxial connectors. In typical operation, the counter has a thermal neutron sensitivity of 0.7 counts/neutron/cm2 throughout a wide range of applied voltage. MECHANICAL: Maximum Diometer . . . .. .. .. ..., 3-1/32 Inches Maximuym Qverall Length . . ... .. .. 13.3/4 Inches Approximote Sansitive Length. . ., ,. 7-1/2 inches Net Weight . . .. .............. 2172

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

FissionCounter

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

FissionCounter

Other

second. The detector is extremely rugged in construction designed to pass MIL-S
167
second. The detector is extremely rugged in construction designed to pass MIL-S-901 for shock and MIL-5td-167
the internal insulators, and it may be operated in any position at temperatures up to
500
the internal insulators, and it may be operated in any position at temperatures up to 500°F.
0.7 counts/neutron/cm2 throughout a wide range of applied vo
0.7
0.7 counts/neutron/cm2 throughout a wide range of applied voltage.
15t 1 15% Mates WIth Amphenol Thickness . . .. .............
2
15t 1 15% Mates WIth Amphenol Thickness . . .. ............. 2 mg/em?2
[— Gos Pressure .,
76
[— Gos Pressure ., .. ... ... ... ... 76 Cm of Hg
High Voltage Electrode to Cose (opprox.)
160
High Voltage Electrode to Cose (opprox.) 160 ppf
Temperature . . . ... .. ... ...,
500
Temperature . . . ... .. ... ..., 500 °F
Operating Voltage , ,
300
Operating Voltage , , . .. ........ 300 Yalts
Operoting Voltage Ploteau (See Figure
800
Operoting Voltage Ploteau (See Figure 2)200 to 800 Yolts
Thermal Neutron Flux Range
10
Thermal Neutron Flux Range. ... 1.4 to 1,4 x 10° nv
APPROX. Amplitude {(Unlocaded)
-4
APPROX. Amplitude {(Unlocaded) . . ... ..... 2 x 10-4 Volts
Inherent Rise Time (Average)
107
Inherent Rise Time (Average). .... 2% 107 Seconds
adjusted to
5
adjusted to 5 counts/second. By varying the pulse height
available. See Figure
1
available. See Figure 1, aofss the section entitled ''Fission
&
1
& 1 t° |

Characteristic

Resistance ot
10
Resistance ot 500°F (minimum). . . .. 10? Chms