Australian Synchrotron, Part 4 - accelerator rings and beamlines (iTWire podcast)

Tony Austin
Monday, 13 October 2008 13:13

Opinion and Analysis

Richard Farnsworth, head of IT and controls at the Australian Synchrotron, in a series of podcasts for iTWire, continues his fascinating insights into the control engineering and information technology used to operate this world-class particle accelerator. This final episode covers the booster and storage rings, the beamlines, and their controls.

Richard Farnsworth (pictured), head of IT and controls at the Australian Synchrotron, showed me over this facility, which is about the size of a covered sportsground. The Australian Synchrotron is sited at Clayton near Monash University, some 20 Km southeast of central Melbourne.

For the first two iTWire podcasts, we started at the synchrotron's control room, then moved on to the server room. In the third podcast segment, Richard gave insights into the software selection and application development process which helped the synchrotron to be ready months early.

In this final podcast segment we toured the two rings, as well as the various beamlines ( where the experiments are carried out, which is of course the basic aim of the entire facility).

As we toured the rings, Richard discussed various aspects of the accelerator's design and control.

Some of the many points discussed include:

• - The different sorts of "synchrotron light" being used (soft and hard).
• - How the booster ring (the small inner one) and the storage ring (the football ground sized outer one) operate, and the control equipment in the "crescent" area between them.
• - How new machinery is prepared by baking and then attached so that the storage ring's high vacuum is maintained. (Losing vacuum in the storage ring is to be avoided at all costs, since it can take take weeks or even months to bring it back online). Ion pumping must be used to create the ultra-low pressure (near 1.60 x 10^-9 millibar, with tiny local variations). As the machine operates, it scours out particles and the vacuum gets better and better.
• - How the orbit of the main beam is minutely controlled, currently by "slow orbit feedback" (later, "fast orbit feedback" will be needed).
• - Why military specification ('mil spec') computers are not needed for synchrotron control.
• - The simple safety method, based on physical keys, used to monitor presence of staff in dangerous areas.
• - The master oscillator, running at close to 499.67 MHz, with the need to make minor adjustments to the frequency to compensate for temperature variations in the beam. Richard explains how the timing pulses are controlled in real time, with 2-nanosecond bunches of electrons, in fact exactly 360 such bunches. These bunches can be shunted from the booster ring into the 113-meter-diameter storage ring at points where there are no electron bunches. Control signals have to be pre-sent at exactly the right time to arrive at the various electromagnets precisely when required. (The computations for this run too fast for any computer to control, so special semi-customized hardware is used.)
• - The importance of having a single safety system across the entire facility. Red is used to signify danger (equipment operating), and green means safe (or off), which may be counter-intuitive but it's more important to have a consistent standard.
• - Virtual beamlines, for remote synchrotron access (made available via the Internet even to high school students in Australia and New Zealand).

The Australian Synchrotron application software podcast episode, a long one (and not for the light-hearted), is available here (MP3 format, file size approximately 47 MB, duration 49:19).

Please understand that we clambered up and down over the outer ring enclosure, and at times passed through rather noisy areas, which is obvious in some sections of this audio segment, and it proved impossible to clean up.

So in this case we have content quality but not the best audio quality, but all the same I hope that you appreciate it.

Why not go and see it all the above for yourself? The Australian Synchrotron Open Day 2008 is coming up on Sunday 26 October, 10 AM to 4 PM. Note that entry to the open day is free but bookings are essential.  Don't miss out.

You may like to subscribe to Lightspeed, which is the monthly newsletter of the Australian Synchrotron. Back issues are available here.

This month's newsletter issue (October 2008) has an interesting piece on how the Aussie Synchrotron differs from the LHC (Large Hadron Collider).