The Engineers at Diamond
Meera - The open day to go inside Diamond starts with a talk explaining the workings of an electron accelerator like Diamond and how different beams of light can be produced by basically getting electrons to move close to the speedof light around a ring. Following this talk is access into the ring itself to see where it all takes place and this is guided by the many engineers and technicians working at Diamond, providing their insight into running such a large scale, but precise, experiment.
David - Hello, my name is David Hawkins. I'm a mechanical design engineer at Diamond Light Source and today I'm a tour guide showing people around the facility.
Meera - David, so what are the key points that you want to get across to visitors as you take them around the facility?
David - A general appreciation of how the machine works and then looking at individual pieces of the machine and then taking them to a talk by a scientist so they can understand what the scientists are trying to get out of the machine. What I do try to do is to make it understandable. For instance, the radio frequency cavities, I try and make analogies to the kitchen and the microwave unit
Meera - And what's the general reception of the crowds you get of the group you take around?
David - I find they are usually aghast, and also the sorts of work that is done. Things like working on the hip joints, the Mary Rose Trust, being able to read the deep sea scrolls without unrolling them, it just carries on and on and on. They really are amazed.
Meera - And what about your role here at Diamond then. You're a design engineer, what do you design and what does it involve?
David - I design bits of the beamline. I've designed things like Diamond windows; diamond fluoresces when it is hit by light and we use that to work out where the beam is. So, as the beam comes into the hutch, we want to know where it is, but designing a piece of diamond 0.9 of a millimetre thick that's got to take a lot of heat without breaking, that takes a bit of effort.
Meera - What's the role of this diamond window with regards to the synchrotron as a whole and how important is it?
David - When you're commissioning that beam, you need to know where that beam is because it can get deflected all over the place. So we have 4 diamond windows down the length of that particular beamline I15, it's the high pressure and extreme conditions beamline, so we have 4 diamond windows down there so as we were getting the light into the hutch, we could find out where it had gone wrong and they were invaluable in setting up otherwise you were working in the dark. You know you had a big dark room and you didn't know where the beam was.
Meera - So they help you guide where to get the beam to I guess and then do they stay in place or are they then removed?
David - They stay in place all the time. The second role is that they provide a barrier so if you have a loss of vacuum you don't contaminate the next section up.
Alan - I'm Alan Morgan and I'm one of the Beam Diagnostic Physicists here at Diamond.
Meera - What do you diagnose here, what's your day to day role at Diamond?
Alan - Well I'm part of the diagnostic team on the machine side so we're looking mainly at the electrons. So we have systems to find out what the position of the electron beam is in the machine, because we need to keep that very stable so that the beamlines have a stable thing to look at and use, and also the amount of charge in the beam, basically how well behaved it is. Also if something is going wrong, to find out what is going wrong with it.
Meera - So is this in every beamline?
Alan - Mainly it's on the machine side. We do have position monitors in the beamlines and the beamlines do have some diagnostics but it varies from beamline to beamline. Some have lots, some have very few.
Meera - And how do you maintain stability, what do you have to look into and what do you have maintain?
Alan - Generally you have feedback systems that keep the stability that we need. So we look at where, for position, we look at where it is and we look at where we think it should be and we try and move it to where it should be. For us, feedback systems are a vital part of keeping it stable enough.
Meera - What are the actual requirements, how stable does the beam have to be and how important is it that it stays stable at this particular level?
Alan - Generally with our feedback systems we can keep it stable to within about 200 nanometres of movement. Some beamlines are more sensitive to motion than others, it really depends on what experiment they want. So there are certain beamlines that we will be more aware of that they are more sensitive and we will check with them that they can see things. They are almost a bit like the canary, if they see something, then we need to check it, if they can't see anything then probably nobody can.
Linda - My name is Linda Pratt and I'm a software systems engineer and I work in the Controls Department.
Meera - so what do you have to control as part of the synchrotron and what do you look in to?
Linda - We have different technical areas of control. Two of the major ones are Motors and the Vacuum systems. We also have diagnostics systems and other instrumentation to monitor the state of the machine, the beamline or indeed part of running the end stations for the experiments.
Meera - So that's quite a few things there. Could you perhaps pick one or two and explain to me how you control them or how they are controlled, and how important it is for them to be controlled.
Linda - The vacuum systems, for instance, a typical vacuum component like a pump will have specialist control piece of instrumentation and we interface that into one of our computers, either a standard PC or a specialist rack-mounted computer and that ties into the monitoring alarm system and the screens that the operators use so the operators can tell, and the experimenters can tell, from their computer screens whether a particular pump is on or off, and if you add all that up together for controlling the vacuum system, it maintains the quality of the vacuum that allows the beam to travel round the storage ring or down the beamlines.
Joe - So I'm Joe Williams, I'm a mechanical design engineer at Diamond.
Meera - What aspects do you design and engineer?
Joe - It's to do with the beamlines. So, outside of the storage ring wall is when you get into the beamlines and we designed the equipment that goes on the beamlines to make sure it's tailored specifically for the sort of science the scientist wants to do on that beamline. Most of the work is on the end stations, most of the end stations are specific to each beamline so we're tailoring the design.
Meera - So, to adjust the beamline accordingly to what's going to be looked at, or....
Joe - It's more handling different samples, on I24, looking at microscopic things, and looking at some of the other beamlines like JEEP, they're looking at much bigger things such as Aircraft turbine blades, so you've got a completely different mechanism you're going to need to handle that to holding a tiny little crystal.
Meera - So you deal with actual components, all the pieces of equipment that handle the samples, or hold the samples for testing?
Joe - Yes, but it's all the equipment before that to tailor the x-rays to be specific to what that sample needs. First of all you need to block out all the radiation that you don't want from the storage ring. So the first component is something called a collimator which is a big block of lead which blocks out all the radiation you don't want, so you just get your x-ray beam coming down the centre of the tube. After that you get things called monochromators which then select the energy of the beamline and you'll get focusing mirrors - slits which are just blades which come in from the sides and bottom and top which define your wide beam into a nice little narrow beam.
Meera - So all of this variety of equipment basically homing it in, so from this large beam just narrowing it and focusing it and narrowing it and focusing it.
Joe - That's it exactly and because that's essentially what your scientist is interested in is getting the right energy of x-rays at this sample.
Meera - So it's clearly not about building a synchrotron and then leaving it to run itself. Every step and every material along the way needs to be monitored closely by the wide range of highly skilled scientists and engineers at the light source.