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DARPA seeks portable muon-making machine to see through almost anything

We currently make muons at CERN, so this is quite the miniaturization job

The United States Defence Advanced Research Projects Agency (DARPA) has initiated a program it hopes will create a portable muon generator.

Muons are subatomic particles that behave a lot like electrons but are around 200 times heavier. As the US Department of Energy explains, "Muons created in the atmosphere constantly hit every inch of the Earth's surface and pass through almost any substance."

Many scientists have noted that measuring the passage of muons offers the chance to measure the interior of whatever object the particles pass through during the 2.2 microseconds or so they exist before decaying into an electron and neutrinos. Boffins have already done this on targets such as the pyramids of Giza, using the constant rain of atmospheric muons that bathes the Earth every day, and techniques that aren't vastly different to those used with gamma rays, X-rays, neutrons, protons, and electrons in imaging applications.

DARPA imagines using muons to do things like scanning buildings "to characterize internal structures and detect the presence of threat materials such as special nuclear materials."

"Other potential applications include rapidly mapping the location of underground tunnels and chambers hundreds of meters below the Earth's surface," the Agency asserts.

Humanity has also figured out how to create muons – but as DARPA admits, doing so "requires such high-energy particles that production is limited to large physics research facilities such as the United States' Fermilab national particle accelerator in Illinois and the European CERN accelerator in Switzerland."

Fermilab watches muons at work in a facility that incorporates "a 50-foot-diameter superconducting magnetic storage ring, which sits in its detector hall amidst electronics racks, the muon beamline, and other equipment" – and operates at negative 450 degrees Fahrenheit (-267.8°C), so you'll need the thick mittens.

DARPA thinks it can do better.

"Our goal is to develop a new, terrestrial muon source that doesn't require large accelerators and allows us to create directional beams of muons at relevant energies, from 10s to 100s of GeVs – to either image or characterize materials," said Mark Wrobel, program manager at DARPA's Defense Sciences Office and boss of the miniature-muon-making program called MuS2.

"Enabling this program is high-peak-power laser technology that has been steadily advancing and can potentially create the conditions for muon production in a compact form factor," Wrobel added. "MuS2 will lay the ground work needed to examine the feasibility of developing compact and transportable muon sources."

"MuS2 aims to employ what's called laser plasma acceleration (LPA) to initially create 10 GeV particles in the space of tens of centimeters compared to hundreds of meters needed for state-of-the art linear accelerators," states DARPA's announcement of the project.

The Agency has given itself two years in which to figure out how to make 10 GeV muons. A second two-year phase will "aim to develop scalable accelerator designs for 100 GeV or greater and produce relevant numbers of muons for practical applications."

To get the job done, DARPA is on the lookout for folks with experience providing Petawatt-level laser facilities, muon target design, and HPC systems to run simulations, among other esoteric skills.

The Agency has invited would-be muon-makers to attend an event on August 5, at which it will explain MuS2 in detail. ®

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