The ANTECH Model N2098 Plutonium Scrap Counter is a transportable high efficiency neutron assay instrument for the measuring of neutron emissions from plutonium bearing samples of scrap and residues. The Model N2098 is based on technology developed by Los Alamos National Laboratory for safeguards and inventory control purposes.

It uses a Passive Neutron Coincidence Counting (PNCC) technique to distinguish the time correlated (coincident) neutrons from the spontaneous fission of the even mass plutonium isotopes from random (single) background neutrons (typically caused by (ɑ,n) reactions from Pu isotopes and ²⁴¹Am alpha particles interacting with low Z materials such as oxygen, magnesium, fluorine etc). The coincidence counting is carried out using shift register electronics.


  • Very high efficiency (>50%) for the detection of ²⁴⁰Pu spontaneous fission neutrons
  • Designed to have as flat a radial and axial detection efficiency profile as possible
  • Can be used with a Multiplicity Shift Register or the N2000 and A2000-15 LVDS for distribution data collection


  • Fast Amptek A-111 based amplifier/discriminator based junction box that reduces dead time effects for doubles and triples, especially at high count rates
  • Annular ANTECH electrically screened Junction Box that ensures comprehensive electrical screening at the termination of the detector tubes
  • ANTECH N2000 and A2000-15 LVDS ensures that pulses which arrive ‘simultaneously’ on different inputs are not lost
  • Cylindrical HDPE moderator
  • Description

    The Model N2098 consists of a detector unit housing 80 ³He tubes and a junction box with 18 charge sensitive amplifiers. The amplifier outputs connect to an ANTECH A2000-LVDS that combines the neutron pulses into a single stream. This pulse stream is fed into an ANTECH N2000 Universal Neutron Counter which captures the information.

    The neutron detection system consists of 80 ³He tubes arranged in four concentric rings. The unit is mounted on a robust portable trolley fitted with castors. The castors can be locked for safety and stability.

    High quality shielded cables provide signal and power connections between the counting electronics and the detector amplifiers. Shielded cables are used for signal and HV cables.

    A portable computer running ANTECH MasterPassive, UNC 2000 User Software or INCC-32 Software controls the measurement process and analyses and presents the resulting data.

  • Specifications

    Measurement Chamber Dimensions
    410 mm H, 200 mm diameter 16" H, 7.8" diameter
    Neutron detectors
    80 3He tubes (Model RS-P4-0820-103) arranged in four rings
    Detector Dimensions
    25.4 mm x 711 mm active detector length at 4 atm 1" diameter, 28" long
    Operating Voltage (V)
    ~1680 V
    Gate Width
    Typically 64 μs
    Die Away Time
    50 μs with gate setting of 64 μs
    4 μs
    ~ISO reals/s/g 240Pueffective 0.42% (1 sigma) for 1 kg PuO2 (20% 240Pu)
    757 mm H, 340 mm W, 340 mm D 29.8" H, 13.4" W, 13.4" D
    392 kg 864 lb
    Operation Temperature Range
    5 to 40 °C