The unseen impact of cosmic rays on electronics

This article by Dr Christopher Frost, Head of Irradiation at ISIS Neutron and Muon Source, looks at the unseen impact of cosmic rays on electronics, emphasises the importance of understanding and mitigating errors to maintain the reliability and efficiency of critical communication systems, and explores ongoing research and testing solutions to build resilience against such disruptions.

There has been a huge growth in internet traffic in the last three decades, and unchecked random errors in the electronic circuits involved can have a significant impact on the reliability and functionality of internet infrastructure. These errors can disrupt the flow of information, causing malfunctions and data corruption that can lead to network failures. Understanding and mitigating these errors is essential to maintain the integrity and reliability of data transmission, minimise downtime, and improve the efficiency of electronic systems.

The ever-increasing role of the internet in our day-to-day lives and economic activity underscores the importance of continually developing and upgrading its technology and infrastructure to meet the increasing demand for data transmission. As the technology progresses, we also have to be vigilant to ensure that cosmic rays do not impact the reliability and robust operation of these key communication systems.

Investigating random errors in electronics

Cosmic rays are high-energy particles that travel through space – from supernovae, quasars, and other active galactic sources – to the Earth's atmosphere. These primary cosmic rays collide with the atmosphere producing a cascade of secondary cosmic rays which reach right down to the ground, made up of subatomic particles including ultra-high-energy neutrons.

These high-energy, invisible neutron particles, constantly present in the atmosphere, can cause what is known as a ‘bit-flip’ in electronics chips. This means that they can change a 0 to a 1 or vice versa in the binary stored data that lies at the very heart of the operation of every digital electronic circuit.

Bit flips occur all the time, but severe consequences have been historically reduced by the development of hardware and software techniques that reduces the ultimate effect of them. However, as electronics become increasingly more complex, more research needs to be done in order to further understand and mitigate against the cosmic ray problem. This is especially true for electronics deployed in safety-critical and commercial applications that need to account for even the smallest probability of a system disruption or failure.

While individual bit flips are considered to be relatively rare events, the huge number of electronic devices, and the global spread of internet infrastructure, including data centres and communication networks, mean that bit flips, while improbable, nonetheless represent a realistic risk. Most of these instances will cause malfunctions that are corrected automatically, but could lead to disruptions in data transmission, server reliability, and network stability if they are not attended to and managed effectively.

Testing solutions using cosmic ray simulators

To develop better mitigation solutions, global internet infrastructure companies carry out ongoing, regular neutron testing at the ISIS Neutron and Muon Source using the ChipIr instrument. Cosmic rays strike at random and in the field are almost impossible to trace, making them challenging to identify or avoid. Specialised facilities, like the ChipIr instrument at the ISIS Neutron and Muon Source in Oxford, allow us to simulate the impact of cosmic rays at a vastly acerated rate so that we can clearly see the effects and develop new ways to detect, correct, and minimise these errors.

ChipIr is a dedicated machine commissioned in 2017, designed specifically for the purpose of subjecting electronics to ‘cosmic stress-tests’ – it is the largest instrument in Europe for this purpose. At the heart of the massive ISIS facility, protons are accelerated to 84% of the speed of light. These are then blasted at heavy metal targets to produce ultra-high-energy neutrons that mimic the specific energies of cosmic rays.

ChipIr is able to accelerate the testing of electronics, bombarding silicon microchips with neutrons at 1.5 billion times the natural intensity so that an hour at ChipIr represents over 170 thousand years in the real environment.

One common hardware solution that has reduced the impact of bit flipping is modular redundancy, in which machines are built with multiple components in case one malfunctions. An electronic system, for example, could be built with three separate processing units so that if one encounters an error, this can be easily detected, by comparing with the remaining two and the malfunctioning unit ignored. The main issue with this approach is that it can be much more expensive to deploy, particularly where commercial cost is important or when dealing with complex electronic systems including large-scale infrastructure.

Building resilience into new technologies

In order to effectively tackle the issue of cosmic ray disruption on electronic systems, there is a need for continued research and innovation in three main areas.

Firstly, we need to understand the precise ways in which cosmic rays interact with different electronic devices – especially with the emergence of new and more complex technologies such as neural networks, computer vision and autonomous systems. Using this knowledge, we can then develop better and more cost-effective hardware and software solutions to reduce the risk of cosmic rays causing disruptions, particularly in safety-critical and commercially critical systems such as internet infrastructure and financial networks. Finally, these solutions need to be tested, which is likely to include exposing them to cosmic ray testing in specialised facilities such as ChipIr, to assess their ruggedness and failure rates in real-world conditions.