The Synchrotron — How a Nuisance Became Treasure

Bend them and light flies off

Bend an electron's path with a magnet and at that instant it throws light outward. The faster it goes the stronger the light, and near light speed the wavelength shortens all the way to X-rays. This is synchrotron light.

The first people to see it were not pleased. An accelerator is meant to load energy into electrons, and here it was leaking out as light. It was a hole in the bucket.

What the light shows

The fifteenth piece said nothing smaller than a wavelength can be seen. The gaps between atoms are thousands of times smaller than visible light, so seeing atoms needs light that short: X-rays.

Atoms in a crystal stand in close rows. Fire X-rays at them and the light splits and overlaps into a pattern (diffraction). Unravel the pattern and out comes where the atoms are. That is how DNA was found to be a helix.

Ordinary X-rays will do, given days and a large crystal. With synchrotron light it takes minutes and a crystal the size of a speck of dust. So drug companies queue to use it: you cannot design a drug until you have seen the shape of the place it must fit.

A little further in

Pohang's two machines

The first keeps electrons circling a ring. Built in 1994 as a third-generation source, it was Korea's first large accelerator. More than twenty experimental stations ring it, so many experiments run at once.

The second does not circle the electrons but fires them straight. Built in 2016, a fourth-generation machine: through a long tunnel of magnets the electrons fall into step, their light piles up, and out comes an X-ray flash as brief and fierce as lightning. Only three such machines existed in the world then.

How it differs from Daejeon's accelerator

The heavy-ion accelerator of the second piece drives heavy nuclei to collision. It breaks things. The synchrotron drives light electrons to squeeze out light. It illuminates things.

They share a name and do opposite work: one makes what did not exist, the other looks into what does.

Not a device but a facility

To run a ring 280 metres round, hundreds of magnets must sit in place to better than a hair's width. A slight tilt in the building throws it off, so the floor floats free and the temperature is held to fractions of a degree.

Like the instruments of the fifteenth piece, this is not used alone. Universities and firms across the country apply for beam time and are reviewed. Once granted, an experiment runs day and night for days. Time with the light on is money.

What you would study to do this

1. Someone who designs and runs the accelerator itself — accelerator physics, electronics. A few dozen such specialists in the country.
2. Someone who takes the light and experiments — chemistry, biology, materials, pharmacy, each from their own field.
3. Someone who keeps the magnets and the vacuum — mechanical and electrical plant. If the vacuum breaks, the light stops.
4. Someone who manages radiation — a job requiring a radiation safety licence.
5. Someone who solves the results — turning diffraction patterns into atomic positions is calculation: mathematics and programming.

The third line is the unexpected job. Without the people who keep the vacuum pipes and cooling lines, no experiment runs at all — a straight road for anyone trained in pipework and electrics, and since the accelerator runs at night, so do they.

Both machines stand inside POSTECH and are run by the Pohang Accelerator Laboratory.

The question that remainsIf something meant for the bin became treasure — which of the things we now call a nuisance is the next one?