Characterisation of collectrons

Description

As part of a thesis financed by the CEA (the French Alternative Energies and Atomic Energy Commission) through the Nuclear Instrumentation project of the Gen2&3 programme, ATRON Metrology carried out tests using its FELIX electron beam, in collaboration with the IRESNE/DER/SPESI/LDCI laboratory (Cadarache) and the LPC (Caen).

Collectrons, or Self-Powered Neutron Detectors (SPNDs), are coaxial detectors made up of two metallic electrodes insulated by a ceramic material, typically alumina (Al₂O₃). They generate an electric current proportional to the neutron flux they detect in reactors.

To better understand the role of the ceramic insulator, Al₂O₃ samples were irradiated in ATRON’s LAETICIA chamber using electrons from the FELIX accelerator. The beam energy (~1 MeV) and intensity (~µA) were precisely controlled. These measurements help to decipher the physical phenomena occurring in the insulator that are responsible for the generation of the continuous current detected by collectrons under real reactor conditions.