Magnets in Fermilab storage ready for use in future projects

The Tagged Photon Lab, once a fixed-target experimental building, is now one of the two major warehouses used for storing magnets. Photo: Fermilab

Those who work with particle beams know that beams have more than one dimension. They are formed to have an hourglass shape here, to flatten to a ribbon there, or to barrel around a curve at just the right width.

The beams’ primary shapers and guides are magnets, and over more than 40 years of developing magnets for diverse projects, Fermilab has accumulated an impressive array of them. Magnets that have completed their original service are stored in one of two warehouses on site. And though they’ve been retired, they’ve not outlived their usefulness.

“Some of these magnets are 35, 40 years old—and they’re fine!” said Technical Division Deputy Head Dave Harding. “You never know when something is going to fill a need.”

Each project’s particular magnet requirements are unique, but that doesn’t mean that magnets have to be produced anew every time there’s a new beam requirement. A rebuilt magnet often does the job perfectly, saving energy, time and money and keeping old radioactive magnets out of expensive landfills.

Three magnets originally built about 1970 to steer beam from the Booster to the Main Ring, for example, have been modified for use in the NOvA accelerator upgrade. The Main Injector project used almost all the regular quadrupole magnets from the Main Ring, along with every single one of the Main Ring’s dipole corrector and quadrupole corrector magnets.

With the wide variety of magnets Fermilab has produced over the decades, there are plenty to choose from. TD’s Quality and Materials Department tracks roughly 400 types of magnets, said Jamie Blowers, department head. More than 4,000 magnets are currently installed in the lab’s accelerators and beamlines.

They run the gamut: dipole, quadrupole, sextupole and octupole magnets fill shelves and pallets throughout the warehouses. Each may be a superconducting, normal-conducting or permanent magnet. Some are the size of a toaster; others are as long as a train car and weigh tens of tons.

TD also maintains the pool of spare magnets in support of accelerator operations. When a spare is needed—even if it’s that multi-ton magnet sitting at the bottom of a stack—Blowers’ team delivers it immediately.

“It’s a 24-7 deal,” Blowers said. “It happens at least once a year—a magnet breaks at midnight, and someone’s on call to deliver a new one.”

As Fermilab expands its scientific program into the Intensity Frontier, many of these legacy components from earlier times will find themselves steering beam once more to uncover new science.

Leah Hesla

These dipole magnets in the Magnet Storage Building once steered Main Ring beam. The second magnet from the top was reworked for the NuMI beamline and now serves as a spare. The rest await new assignments. Photo: Fermilab