The ANTECH Model N2442 Active Well Coincidence Counter (AWCC) is a transportable high efficiency neutron counter for the measurement of plutonium and uranium. The AWCC was originally developed by the Los Alamos National Laboratory (LANL) in the United States.

ANTECH has added performance enhancing features including:


  • Serves as both active neutron detector for measuring uranium and passive neutron coincidence detector for measuring plutonium
  • Provides complete passive and active assay system when used with most commercially available neutron coincidence or multiplicity counters
  • Reproduces the physics and measurement characteristics of the original LANL Active Well Coincidence Counter design


  • Adjustable size measurement chamber
  • Two americium-lithium sources for the measurement of uranium
  • Advanced electronics with de-randomising mixer buffer circuitry to reduce count losses
  • Robust construction
  • Description

    Active Mode

    For uranium measurements the N2442 is used in Active Mode. Two americium-lithium sources are inserted (one in the base and one in the plug unit) and the system is operated in random driver mode. Uncorrelated neutrons produced by the Am-Li sources induce fission in ²³⁵U samples in the measurement chamber. The coincidence counter electronics of the ANTECH N2000 Universal Neutron Counter (UNC) can be used to determine the coincidence count
    rate, which is attributable to the induced fission in the ²³⁵U. Using this method the mass of uranium is readily determined.

    Two action modes are available depending on the size of the ²³⁵U sample:

            1. Thermal Active Mode is employed to measure low-enriched uranium materials. In this mode the sleeve and end plug cadmium coverings are removed. The detection level of this mode is approximately 1 gm of ²³⁵U.
            2. Fast Active Mode is employed to measure highly enriched material such as uranium metal, uranium thorium fuel and LWR fuel pellets. In this mode the cadmium plates and sleeve are inserted and the detection limit is approximately 23 gm of ²³⁵U.


    Passive Mode

    In Passive Mode the americium-lithium sources are removed and the N2442 can function either as a neutron coincidence counter or a neutron multiplicity counter, using the appropriate features of most commercially available neutron coincidence and multiplicity counters.

    The detector measurement chamber can be enlarged by removing the two internal polyethylene disks and the nickel reflector. It can also be operated in the horizontal position with the end plugs removed and with a material test reactor (MTR) holder in position for the measurement of uranium in MTR measurements.

  • Specifications

    (Including handle and frame)

    1040 mm x 645 mm x 711 mm

    (40.94 in x 25 in x 27.99 in)
    Sample Cavity Dimensions
    Chamber is adjustable

    (H x D)

    206 mm x 229 mm
    (8.11 in x 11.77 in)
    Approx. 130 kg (286.6 lb)
    Am-Li sources
    4.8 x 10,000 n/sec (2 off)
    Detector Channels
    42 ³He detectors at 4 atm pressure,
    6 Amptek charge sensitive amplifiers
    Detection Efficiency
    26% - 31%
    Electrical connections
    High Voltage = SHV
    5 V Supply For Head Amplifiers = BNC
    Signal Output = BNC
    LVDS Signal Output = 37 Way male 'D' Cable supplied