Neutron Measurement Testing

Neutron measurement testing verifies the performance of neutron detection instruments. It confirms that detectors, survey meters, portal monitors, and dosimeters meet specified sensitivity, accuracy, and alarm requirements. Teams conduct this testing before deploying instruments at nuclear facilities, border crossings, and CBRN operations.

Calibrated neutron sources deliver known fluence rates to the instrument under test. Californium-252 (Cf-252) is the most widely used source. It emits a broad-spectrum fission neutron field with a mean energy of 2.1 MeV. Americium-Beryllium (Am-Be) sources provide a higher-energy alternative for fast neutron response testing. Furthermore, moderated source configurations surround the primary source with polyethylene spheres of defined diameter. These produce reference thermal, epithermal, and fast neutron fields at the detector face — testing energy-dependent response across the full operational neutron energy range.

Sensitivity testing measures the minimum detectable count rate above background. This verifies the instrument responds to neutron fluence rates from shielded special nuclear material at operationally relevant distances. Alarm threshold testing confirms audible and visual alarms activate at programmed set points. Additionally, Bonner sphere spectrometry maps detector response across neutron energies from thermal to fast — using polyethylene spheres from 2 to 12 inches diameter around the detector.

Gamma rejection testing places the detector in high gamma dose rate fields from Co-60 or Cs-137 sources. It confirms the instrument does not produce false neutron counts above the rejection specification. Moreover, this test directly replicates conditions at border portal monitors where legitimate medical isotopes in cargo must not trigger false alarms.

Calibration certificates reference NIST or IAEA measurement standards. They include source activity, uncertainty estimates, and pass/fail determination against ANSI N42.17B, IEC 62244, and ISO 8529 acceptance criteria.

Tactical Supply Pakistan supplies neutron measurement testing equipment for nuclear instrument qualification, border monitor acceptance testing, and CBRN calibration procurement across Pakistan.