Physicists Come From All Around for "Beam Time" at WMU

Jun 8, 2017

WMU particle accelerator lab director Asghar Kayani stands next to the acceleration tank.
Credit Sehvilla Mann / WMUK

If you’ve heard of Western Michigan University’s particle accelerator, you might have also heard that it’s a secret machine involved in double-secret research. The directors of the lab say that's completely untrue, though it is true that you should not stand next to the machine during some experiments. At a moment that posed no risk, "Why's That?" and mechanical engineering student Peter Grohs saw the facilities up close.


Interest in the accelerator runs in Peter’s family. When his dad was a student at Western in the 1970s, he set out to find the machine himself.

“You couldn’t Google it back then,” Peter notes.

“He knew it was in Rood Hall. He just kept trying stairwells and doors and according to him he just found it down here, found some technician here and the technician showed him around a little bit and sent him away probably because he was busy,” he says.

Peter and I made our own trip to the sub-basement of Rood Hall to find out more about it. We met with physicist and accelerator lab director Asghar Kayani and his colleague, longtime WMU physics professor John Tanis.

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We start in the control room. Tanis says the instruments that run the accelerator haven’t changed much since the machine came to Western from Argonne National Laboratory near Chicago in 1969.

“We don’t even have touch screens in here. Everything’s got control knobs and things like that,” Tanis says.

“One of our students for example pasted a knob over there, and you see that underneath the knob it says self-destruct?” Kayani asks.

Despite its age and a few absurd embellishments (you can find containers of “shark repellent” in the lab as well), after nearly fifty years at the university, the particle accelerator remains a sought-after tool. Physicists come from around the US and even abroad to use it. Tanis says Western’s using the accelerator for leading-edge research right now.

Essentially, the machine’s function is to generate a beam of charged particles – protons for example – which then gets sent toward a target. Researchers might study the particles themselves, or they might want to know how the particles changed the target. (Accelerator labs often refer to physicists' scheduled time with the machine as "beam time.")

The beam goes around a 90-degree bend after it exits the tank.
Credit Sehvilla Mann / WMUK

Kayani has used the accelerator to alter small pieces of diamond to make them easier to slice. He says you first create a beam of charged particles from, say, carbon atoms,

“And then tune the energy of the beam so that it can stop at a certain distance. And in our case it could be just three micrometers below the surface. And when we keep actually creating damage to that layer, eventually what happens is that becomes so much damaged that instead of a diamond now it’s graphite,” he says.

Graphite, of course, is the soft stuff that makes up a pencil lead. The thin layer of graphite the accelerator can create is much easier to cut than the diamond on either side. Slice it and you get an extremely thin wafer that Kayani says can be used in electronics.

“So this is the control room. Let’s go to the accelerator room where you can see the actual machine,” Kayani says.

We round a couple of corners, and there’s the accelerator tank, which looks much bigger in person than it does in the picture on Western’s website. It’s forty feet long according to the physics department, with the proportions and even the color of a salami.

It’s painted brown  - with a few gold accents – in honor of the university.

This is where particles get exposed to very-high-voltage static electricity, which causes them to speed up. The beam comes out of the machine in a tube that takes a right turn, and, Tanis says,

“There’s a switching magnet here that directs the beam into one of four beam lines, this gray box here.”

That allows researchers to pick up their beam of particles and do their experiments.

Peter gathered some questions about the accelerator from friends.

“One I heard from a physics student that I know. He says that when it’s running, the air shimmers and you shouldn’t stand in there because you will die,” he says.

Tanis and Kayani laugh. “I don’t think so,” Tanis says.

“No actually, you won’t die but I mean there could be a potential damage to your body because this machine can produce radiations,” Kayani explains.

Forget 70 miles an hour: Kayani says the accelerator can run a beam of protons at 36,000 miles per second – and crash them into a target, causing radiation. That’s why, as you walk around the lab,

“There is everywhere you have a three feet thick concrete wall. And that’s actually provides the shielding,” Kayani says.

But Tanis says most of the beams don’t run fast enough to create radiation.

“We’re running a very slow beam today and we can be in the target room and be around where the beam hits the target, no problem at all.”

As for the air shimmering during an experiment, Kayani says doesn’t happen either.

“I asked for questions from people I know and these are the questions that came up!” Peter says.

“Okay,” Kayani says, laughing. “Interesting!”

If something in Southwest Michigan has made you curious, Why’s That? wants to know about it!