The ANTECH Model 2004 is a simple, non-quantitative neutron slab counter for the de-

tection of curium contamination in waste drums, boxes or crates before or after a more

quantitative measurement of fissile/fertile content is made by some other non-destructive

assay techniques (for example, Tomographic Gamma Scanning).

The qualitative detection process relies on the fact that the spontaneous fission output (per

gram) of curium isotopes (principally 244Cm) is some ten thousand times greater than an

equivalent mass of 240Pu. Thus the presence of curium can be detected by comparing the

expected neutron output (based upon the downstream quantitative measurement) with the

efficiency corrected totals output from the curium monitor.

The unit is a single neutron slab counter module consisting of four 3He detector tubes in a

rectangular high-density polyethylene block. The moderator block is clad with a skin of

aluminium sheet. Brackets are provided to attach the module (weight ~46 lbs.) to the wall

of the room or laboratory. A junction box for the four tubes is housed at the top of the

module and combines and amplifies the detector signals and distributes high voltage to

the detector tubes. The approximate overall size of the module is 1100 mm x 200 mm x

The output from the junction box on the detector module is connected to the ANTECH/

ORTEC Advanced Multiplicity Shift Register (AMSR-150) by means of coaxial cable.

The AMSR contains circuitry, which provides and monitors the high voltage power sup-

ply for the 3He tubes and the low voltage power supply to provide power to the head am-

plifier.

The ANTECH electrically screened junction box ensures comprehensive electrical

screening at the termination of the detector tubes. It houses the fast charge sensitive am-

plifiers, which employ the AMPTEK A-111 based amplifier. The modular nature of the

Junction Box and its construction allows 3He tubes to be replaced easily without the need

to disassemble the junction box.

Each 3He tube is connected via an HN connector to the junction box and supplied with

HV. Two SHV sockets are provided for HV In and HV Out. The LV compartment of the

junction box contains the Amptek A-111 pre-amplifier board and the LV socket (BNC).

The signal is fed out of a single BNC socket directly to the AMSR.

Detection efficiency: 1% (*)

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Operating Voltage: ~1650 volts

Electrical connections:

·

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Weight: 21kg (46lbs) approx

High voltage - SHV

·

Dimensions, excluding brackets: 1100

5V supply for head amplifiers - BNC

·

mm x 200 mm x 80 mm (43.3" x 8" x

Signal output - BNC

3")