Neutron studies underpin more reliable avionics technology

30 Apr 2026 - Peter Hurrell

Researchers have used the ChipIr instrument at ISIS to understand the effects of atmospheric neutrons on a core component of an inertial navigation system. The researchers exposed the devices to neutrons in ChipIr to simulate long-term environmental exposure. They found that the devices suffered no long-term permanent loss of function.

Four photos. The first shows the position of the eIMU in the ChipIR instrument, with the direction of the neutron beam labelled. The next three show the orientation of the eIMU at different stages of the experiment.

The experimental setup. From https://doi.org/10.1016/j.microrel.2026.116010

Their finding will help understand how such devices are affected by atmospheric neutrons and will inform strategies to mitigate such damage in future.

Bombarded by cosmic rays

Every second of the day, the Earth is bombarded by cosmic rays. Arriving from deep space, they strike atoms in our atmosphere and generate a spray of atmospheric neutrons and other particles that can reach the ground. While life on Earth has evolved to repair the damage caused by such radiation, our electronics have not. This is especially important for aircraft and space systems operating higher up in the atmosphere, where they are exposed to a much higher number of these atmospheric neutrons than at the Earth’s surface.

The ChipIR instrument at ISIS was developed to address precisely this problem. With it, researchers can expose electronics to a neutron beam that simulates atmospheric neutrons and monitor their effects.

For this experiment, the team of researchers from ISIS, University of Rome “Tor Vergata”, Thales Alenia Space Italia, Northrop Grumman Italia, Consiglio Nazionale delle Ricerche, and IPCB-CNR tested an enhanced Inertial Measurement Unit (eIMU) developed by Northrop Grumman Italia (NGI). The eIMU uses gyroscopes and accelerometers to measure velocity and angular changes, as well as GPS navigation sensors. The research team could monitor the data returned by the various sensors to spot any unusual activity.

Transient errors

The researchers were watching for malfunctions in the eIMU known as Single Event Effects (SEEs). SEEs can result in either a temporary or permanent loss of function. In their study, the team found only temporary function losses, classified as either Single Event Transient (SET) or Single Event Functional Interrupt (SEFI), suggesting the high level of neutron exposure did not permanently damage the eIMU. All the errors caused by neutrons were transient and could be recovered from either through manual power cycling for SEFIs, or via automatic error-correction mechanisms for SETs.

A failure in time analysis showed that the velocity measurements were most susceptible to disruption by atmospheric neutrons, while angles of rotation and acceleration measurements were less affected.

Although the tests provide a basis for understanding how the eIMU were affected by atmospheric neutrons, the researchers caution that the results are not applicable to eIMU applications in space, where components are exposed to additional radiation hazards. The devices would also need to be tested under specific mission conditions before deployment.