Inside a large particle accelerator, an invisible shower of gamma rays reigns, like leaving a glass thread under an X-ray machine switched on for years. Ordinary electronics there quickly fail, yet data from the detector still needs to get out. The solution is optical fiber: a thin glass core that carries light.
But glass darkens under irradiation: radiation knocks atoms out of the lattice, scattering and weakening the light. Scientists took telecom fiber doped with germanium and irradiated it with gamma rays from cobalt-60. At a dose of 300 kGy, equivalent to three hundred thousand chest X-rays focused on one spot, light loss was only 0.05 decibels per meter. That means after a hundred meters of cable, the signal would weaken by just half.
At low temperatures, around minus fifteen, the fiber suffers more: cold hinders the glass's ability to "heal" damaged sites. But once the radiation source is removed, defects dissolve within hours, and transparency returns to nearly its original level — regardless of whether irradiation was fast or slow, warm or cold.
Such fiber can already be laid inside detectors for future experiments: it fears no radiation, takes up little space, and transmits data faster than copper wires. Light in a glass core proves tougher than it looks.
A dose of 300 kGy is thousands of times lethal for humans, but for glass fiber it's just a slight clouding that disappears after a few hours of rest.