Thermal Neutron Detectors

Thermal Neutron Probes


Thin Film Deposition



Cambridge Microfab Ltd
Broadway, Bourn
Cambridge CB23 2TA

T: +44 (0) 1954 718100
F: +44 (0) 1954 718164

Solid State Thermal Neutron Detectors

  • HT-50 silicon carbide sensors for use up to 175oC
  • AT-25 & AT-50 silicon sensors for use up to 55oC
  • suitable for medical, space, military, nuclear, laboratory, educational & environmental applications
  • configurable as pixellated structures for applications requiring spatial discrimination
  • ideal for hand held or field use
  • compact, lightweight & robust
  • low voltage makes operation intrinsically safe
  • low power consumption so very suitable for battery operation
  • single pulse per effective neutron output at low flux levels
  • useful output over many decades of neutron flux intensity
  • high thermal neutron specificity
  • insensitive to gamma radiation
  • uniform response (no edge or wall effects)
  • semi transparent to neutrons so low perturbation of neutron field
  • highly asymmetric (quasi-2D) detector element (length & width are thousands of times greater than the active thickness)
  • wide operating temperature range
Neutron Sensors

Our detectors are rugged heterodiodes for detecting incident thermal neutrons. We believe they are the most efficient solid state neutron sensors commercially available today. While the basic devices are always 2 wire diodes, multiple packaging variations are available to suit specific customer needs.

Other solid state neutron sensors typically comprise a p-i-n type diode detector to which an external neutron reactive layer is applied as a secondary operation. The function of the diode is to detect neutron reactions in the external neutron reactive layer.

Cambridge Microfab thermal neutron diodes are made differently. The neutron reactive layer is created as an integral part of the diode production process and the neutron reaction product originates within the diode structure. This gives rise to higher detection efficiency than can be achieved with the conventional approach

Neutron Sensors

Our sensors stop about 1 in 7 thermal neutrons and produce useable signals from > 1 in 2 stops, giving an overall efficiency of 7.5%. The measured neutron count rate is directly proportional to the incident neutron flux and the sensor area. The count rate is also modified by the sensor configuration and the lower limit of discrimination used in the signal chain.

AT50 & HT50 detectors behave much like a very thin 50mm2 3He tube filled with 0.509 cc of 3He but without the high voltages, so our sensors are intrinsically safe.

AT sensors were originally developed for planetary space studies in support of the European Space Agency's Science & Robotic Exploration programme, meeting requirements for low applied voltage, high efficiency & ease of operation in a compact, robust package.

HT series Silicon Carbide based sensors have been developed more recently. They offer important advantages including reduced leakage current, better radiation hardness, a much higher maximum operating temperature and wider operating temperature range.

AT-25 Thermal Neutron Sensor
AT-50 Thermal Neutron Sensor
HT-50 Thermal Neutron Sensor