Neutron Generator Probe for logging porosity without radioactive source

Neutron emission from grounded target at generator end with detection
in a compensated probe configuration using near & far detectors


Mount Sopris Instrument Company, together with Starfire Industries LLC, are developing a new neutron probe that eliminates the use of radioactive materials for neutron production. This innovative solution will provide a welcome addition for well loggers and geophysicists who are restricted from using Am-Be or Deuterium-Tritium (D-T) sources.

Using a 4 Curie equivalent Deuterium-Deuterium (D-D) fusion neutron generator, the QL40-nGEN will provide radiation on/off capability, increasing safety for operators and avoiding the regulatory burden associated with radioactive sources.

Mount Sopris Starfire Industries

Starfire Industries’ patented nGen™ technology allows for neutron generation from a grounded target located at the end of the accelerator head.  This end-mounted target allows very close coupling with detectors for innovative near/far detector combinations to maximize detector sensitivity and fidelity of measurements in and around the borehole to take advantage of the 2.5 MeV monoenergetic neutron’s increased sensitivity.  The high-pressure housing is sized for small diameter logging and all components are designed to withstand high ambient temperatures.

The QL40-nGEN downhole logging tool will be stackable within the Quick Link (QL) product line or it can be run as a standalone tool. It can be run in any borehole environment using the MATRIX or SCOUT data acquisition consoles.  A preliminary rendering of the integrated neutron probe is shown below.


Neutron Generator Probe Borehole Logging

Rendering of MSI/Starfire neutron probe features


Borehole Logging Neutron Probe

New neutron probe approximate dimensions


  • Quantitative In-situ Porosity
  • Petrophysical Properties
  • Aquifer Quality and Delineation
  • Moisture Content of Unsaturated Media
  • Used with other logs, can detect gas zones and identify gas-liquid contacts

Operating Conditions

Borehole Fluid
[X] Water
[X] Mud
[X] Dry

[X] Uncased
[X] PVC Borehole
[X] Steel

[_] Required
[X] Not Necessary

Features & Benefits

  • Avoids radioactive material with safe D-D fusion
  • No specialized storage required
  • Ease of transport
  • Simple permit for handler
  • Neutron emission at end of generator allows much closer near and far placement of detectors
  • Generator remains off until switched on
  • Neutron generator integrated in the tool
  • HV supply & RF generator integrated in neutron generator
  • Onboard microcontroller with serial communications
Compare this to a Conventional Neutron Probe…
  • Obtain your own radioactive source
  • Purchase costly, secure storage of source
  • Procure safe transport of source
  • Professional license required for handling
  • Neutron emission remains far from detectors
  • Insurance
  • Risk of lost source in the well
  • Difficult for water and environmental use

Specifications – Metric/Imperial

  • Base Yield:  107 n/s
  • Neutron Energy:  2.5 MeV DD
  • Ion Source Type:  Electrodeless RF
  • Lifetime:  500 hours operational warranty or 12 months on shelf
  • Input Voltage:  18V, 100V DC regulated
  • Input Power:  100W base, 250W option
  • Operating Voltage:  120-140 kV
  • Operating Temperature:  85˚C base (125˚C shallow well)
  • Operating Pressure:  2900 psi (200 bar)
  • Outer Diameter, Housing:  1-11/16” (43 mm)
  • Inner Diameter, Components:  1.30” (33 mm)
  • Length:  ~ 78” (198 cm)
  • Weight:  ~ 25 lbs (11.34 kg)

QL Stack Possibilities

  • QL40nGEN + QL40GR (Gamma) + QL40DEV (Deviation): Exploration, Borehole Deviation
  • QL40nGEN + QL40GR (Gamma): Exploration, Petrophysical Properties
  • QL40nGEN + QL4SGR (Spectral Gamma) + QL40ELOG (Resistivity): Groundwater Suite tools, Quantitative Analysis, Lithology, Porosity Estimates

To learn more about our classic nuclear tools:

To learn more about the Starfire 100B:

The anticipated product release of the QL40-nGEN is late 2020.


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