Nuclear Fusion Reactors Could Produce Dark Matter, Physicists Show

Quick Overview

Physicists propose that future nuclear fusion reactors, particularly those designed for Deuterium-Tritium fusion, could accidentally produce axions, a hypothetical dark matter particle, which could potentially be detected through energy loss or by converting them into photons in a strong magnetic field, offering a new, albeit indirect, avenue for dark matter searches, although the prediction of this production is currently based on theoretical calculations rather than direct observation.

Key Points: Recent studies suggest that nuclear fusion reactors, such as those using Deuterium-Tritium (D-T) fuel, might generate axions, which are prime candidates for dark matter particles. The production mechanism involves axions being created during the fusion process and subsequently interacting with the reactor walls, or through the decay of tritium. Neutrons produced in D-T fusion are electrically neutral and do not interact strongly with magnetic fields, making them difficult to trap within the reactor plasma like charged particles. The proposed method for detecting axions in fusion reactors relies on them converting into photons within the strong magnetic fields of the reactor, a process that would manifest as a small energy loss. Current dedicated axion search experiments, like ADMX at Fermilab, have not yet found evidence for axions, suggesting that if they exist, their mass or coupling strength may require different experimental approaches. The authors of the relevant paper estimate the number of axions produced, suggesting that if axions exist, fusion reactors could generate a significant, though currently unmeasured, flux. The video humorously rates the idea of fusion reactors producing dark matter as 7/10 on a 'bullshit meter' because it relies on unproven physics (axions) and the detection method remains theoretical.

Context: The video, presented as a segment of 'Science News with Sabine Hossenfelder,' discusses a recent theoretical paper suggesting that current or future nuclear fusion reactors could serve as accidental factories for producing axions, a hypothetical elementary particle often invoked to explain dark matter. The host contrasts this proposal with the standard understanding of fusion reactions, which primarily produce helium and massive amounts of neutrinos, and briefly touches upon the challenges of detecting axions using dedicated experiments like the Axion Dark Matter Experiment (ADMX) at Fermilab.