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November 7, 2009

Concrete Blocks

Concrete blocks. Absolutely everywhere. That's my dominant impression of this international particle accelerator research centre after the first month. Concrete blocks shielding the outside world from radiation emitted by the shiny things hiding behind them. And generally, the bigger the pile of concrete blocks, the cooler the thing that's lurking behind.

Here are some photos from today's open day at DESY. Most of the things shown (everything apart from FLASH and XFEL) have nothing to do with what I work on, but they're still exciting to look at. The HERA and PETRA tunnels aren't normally open, least of all to the public, and there probably won't be another opportunity to see them for years. In pictures 38, 40, 42, 45, 46 and 51, you can see the sequence of bits of pipes and coils which guided electrons from PETRA, physically above HERA, into HERA's electron ring. HERA was switched off in September 2007, but almost all of it is still in the tunnels. You can also see wider views of the machine. The cylindrical pipe thing on the top is the superconducting ring of magnets which guided protons, and the pink boxy thing underneath is a normally conducting ring of magnets for the electrons. You can even see what's underneath the pink metal cover, but it's not very exciting. Then there's a spin rotator which alters the polarisation of the electrons. A bit further down, you can see the electron and proton rings being brought closer together (the electron beam pipe is the thin bronze-coloured thing just in front of the yellow thing), and then going through the final focusing magnets before colliding with one another in the next room. Not that you can see anything except concrete blocks, because that bit is just way too cool.

And it needs a whole lot of cryogenic stuff to make it work.

PETRA was previously used for particle physics, before being turned into a pre-accelerator for HERA and more recently (last year or so) into a synchrotron radiation source for (e.g.) protein crystallography. This thing is still used - in fact it's one of the most modern synchrotron X-ray sources in the world - but it wasn't switched on while we were in the tunnel, otherwise we would have been fried. Naturally it's hidden behind a huge wall of concrete blocks.

There are plenty more photos to see beyond the ones linked here..!

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