First beam to MuCool Test Area

The MuCool Test Area hall viewed from the downstream end of the magnet looking toward the beamline. The beam absorber and collimators are visible in the foreground and the beamline in the background. Photo: Yagmur Torun, Accelerator Research Center.

A decade ago, a muon collider was considered nearly impossible. Now, scientists at Fermilab’s MuCool Test Area are a step closer to testing some critical components for such an accelerator.

In February, the MTA, located near the southern end of Fermilab’s linear accelerator, received its first beam of particles. The new beamline will allow scientists to test equipment for muon cooling, a critical part of development for future muon colliders.

“The beam entered the center of the hall last week,” said MTA coordinator Yagmur Torun. “We’re making great progress.”

The new beamline from the linac to the MTA was made possible by the External Beamlines Department.

“We’re very happy to see the new beam reach the MTA,” said External Beamlines Department Head Craig Moore. “This achievement was years in the making, and the team worked hard to develop and install the shielding and safety components necessary for the new beam.”

The path to building a muon collider is a difficult one. Muons, the electron’s heavy cousins, are unstable and decay in two millionths of a second.

Scientists can create large numbers of muons by steering a proton beam into a target of dense liquid. Once the muons are created, magnets send them in the right direction. At this stage, the muons are still too diffuse to create useful collisions.

At the MTA, scientists are exploring methods to cool muons and corral them into dense beams for high-luminosity collisions. One proposed method, known as ionization cooling, would focus muons into a laser-like beam by forcing them through a series of magnets and absorbers filled with liquid hydrogen. The hydrogen slows the muons and absorbs their energy, while the magnetic fields narrow the beam. This process has to take place quickly, before the muons decay into electrons and neutrinos.

This ionization cooling method is necessary for the success of a future muon collider, said Alan Bross, co-spokesperson for the Muon Collider collaboration. With the new beam to the MTA, experimenters can soon put this method to the test. Bross expects to see crucial results from MuCool in the next four months.

For more information on research and design for a muon collider, check out this article in symmetry magazine.

— Cynthia Horwitz