They were first noticed in experimental runs in the early 1980s as short tracks in film emulsions or plastic leaf detectors connected to medium-energy particle accelerators.
The direction of the tracks demonstrated that they were the results of reactions taking place within the accelerator targets, but they stopped so quickly in the detectors that no obvious explanation for their behavior could be offered.
A flurry of theoretical explanations followed, but over time a series of follow-up experiments failed to find strong evidence for the anomalons, and active study of the topic largely ended by the late 1980s.
As the high-energy community moved to larger accelerators and exotic particles and reactions, new detectors were introduced that worked on different principles.
One such experiment was being carried out on the Bevalac at the Lawrence Berkeley National Laboratory using Argon 40 accelerated to 1.8 GeV and then smashed into a copper target backed with a nuclear emulsion detector.
The vast majority of the particles continued into the emulsion over much greater distances, in keeping with expectations and the results of all previous experiments on the machine.
[6] More recently he has claimed that the particles in question are actually the elusive axion, long thought to be part of the standard model, but unseen in spite of decades of searching.