The ANTECH G3501 Plutonium Isotopic Spectrometer is a comprehensive measurement system for the determination of plutonium isotopic ratios. This information is required for both neutron and calorimetry measurements of plutonium, in order to determine the masses or activities of the individual plutonium isotopes. The G3501 may also be used for the isotopic ratio measurement of mixed oxide fuel material containing a mixture of both plutonium and uranium.


  • Compatible with both PCFRAM and MGA Isotopic Analysis Packages.
  • Automatic sample measurement based on can size.
  • Sample is rotated and raised and lowered for multiple cycles to ensure optimum counting.
  • High Resolution Safeguards Quality HPGe detector for high measurement precision.
  • Compatible with both Electro-Mechanical and Liquid Nitrogen cryogenics.


  • Rotation Platform and vertical translation for full sample view.
  • 25% efficient High Resolution Safeguards Quality shielded HPGe detector.
  • Adjustable Collimator for detector dead time minimisation.
  • Set of Cadmium filters of varying thicknesses for Am²⁴¹ filtering.
  • ANTECH IsoScan software package.
  • Description

    The ANTECH Model G3501 Plutonium Isotopic Spectrometer is a high accuracy assay system for the determination of Plutonium Isotopic ratios in small sample cans. The system consists of a steel walled measurement chamber into which a sample can is placed for assay. During the measurement, the sample can is moved in front of the HPGe detector and a spectrum acquired, which is then processed either by PCFRAM or MGA.

    The system is designed to operate with Ortec SGD series ‘Safeguard’ detectors, with a nominal 25% efficiency. The detector is mounted within a lead shield lined with tin and copper, including lead back shields, to provide total protection and ensure only contribution from the sample can are measured. For a measurement, a sample scan is loaded onto a Sample Carriage, which rolls via guide rails onto the rear of the Measurement Chamber Door, to provide a loading platform. Once loaded, the low friction bearings enable an easy loading onto the rotation platform within the measurement chamber. When the Chamber Door is shut, a measurement can be started, during which the sample is rotated, and translated vertically up and down through a number of cycles, based on the selected sample height. This is done to ensure an accurate measurement of the sample for the detector. Once complete, the rotary and vertical axes are returned to the zero position, and the Chamber Door can be opened to withdraw the sample.

    The G3501 features an Adjustable Shutter consisting of two steel plates, mounted in front of the detector. In situations where the count rate are causing poor measurement statistics in a sample (high dead time), the shutter plates can be closed to limit the field of view of the detector and shield the detector. The shutter can be manually opened or close using the push buttons on the front of the instrument, with the count rate being shown on the small LCD screen. Alternatively, the shutter can be automatically controlled with the ANTECH IsoScan User Interface software package, automatically adjusting based on a configurable count rate value.

    On top of the system, a system Electronics Enclosure is positioned, containing all electronic components, and power input and distribution. On the front of the enclosure, a set of selection switches allow the system to be manually operated, along with an LCD screen which shows the count rate of the detector. This can be used to manually set the Adjustable Shutter as required. The switches allow the operator to all axes of motion.

    The G3501 includes a comprehensive safety design, with roller switches prohibiting motion if the Chamber Door is not shut, and a set of optical and physical limit switches on the axes of motion. An emergency stop switch removed power from the motors immediately, providing a safe operating system.

    The ANTECH IsoScan software package offers the operator an easy User Interface to configure and control the system. It allows automatic measurement and control of the axes, and also allows for configuration and setup the PCFRAM and MGA analysis software packages. All software packages are loaded onto an embedded control unit within the electronics enclosure for access both directly, or via remote desktop access.

  • Specifications

    Sample Size
    100mm, 200mm, 300mm & 400mm typical, although customisable. 4", 8", 12" & 16" typical, although customisable.
    Analysis Software
    ANTECH IsoScan operating with either PCFRAM or MGA
    Variable Collimator Range
    Infinitely adjustable using manual controls.
    Automatic adjustment through configurable limits in ANTECH IsoScan software.
    <25% Ortec Safeguards Quality Detector, with higher and lower efficiency options available.
    55mm Lead shielding, lined with tin and copper, with lead back shields 2.17" Lead shielding, lined with tin and copper, with lead back shields
    Detector Cryogenics Options
    Electro-Mechanical cooler
    30L LN2 Dewar
    Ortec Möbius LN2 Recycler
    Digital MCA
    Ortec DSPEC Pro
    Operating Voltage (V)
    110 - 240Vac, Single phase
    Frequency (Hz)
    50 - 60Hz