The sensor is built on PGNAA (Prompt Gamma Neutron-Activation-Analysis) technology. PGNAA is not a new technology – although not widespread. In addition to a number of applications within the re-search area PGNAA is used for characterisation of coals for power plants, ores in the mining industry and raw materials for cement kilns. FORCE has applied this technology to certain types of waste streams, including battery waste. FORCE has patent for this application.

The mode of operation of the sensor is as follows:

• The neutron source emits fast (high energy) neutrons
• The moderator slows down the neutrons, and they become reactive
• The neutrons react with the nucleus of elements in the object in the detection field
• The element emits a specific gamma-spectrum (colour)
• The gamma detector detects the gamma-spectrum
• The computer analyses the spectra and estimate the content of the elements