To increase the neutron sensitivity of the PM1401GNA and PM1401K radiation detectors with build-in He-3 neutron detectors, the use of the external neutron chamber moderator is highly recommended. It is well known that a He-3 type detector detects more efficiently thermal (low energy) neutrons than fast (high energy) neutrons. The external neutron chamber converts fast neutrons to thermal thus making more efficient detection of the high energy neutrons.

The External Neutron Chamber Moderator is not a part of a standard delivery kit for PM1401GNA and PM11401K instruments. This accessory should be ordered separately.