Military Embedded Systems

DARPA embarks on muon project to enhance defense, scientific capabilities


July 28, 2022

Lisa Daigle

Assistant Managing Editor

Military Embedded Systems

DARPA embarks on muon project to enhance defense, scientific capabilities
Image courtesy DARPA.

ARLINGTON, Va. The Defense Advanced Research Projects Agency (DARPA) launched a program called "Muons for Science & Security" (MuS2) with the aim of discovering a compact source of muons, which are deeply penetrating subatomic particles -- similar to electrons but about 200 times heavier -- that can be used in a variety of defense and scientific applications because they travel easily through dozens to hundreds of meters of water, solid rock, or soil.

Producing muons is extremely challenging, according to information from DARPA, because such production requires a very high-energy, giga-electronvolt (GeV) particle source. Currently, two primary sources for muons exist: One is harnessing cosmic-ray interactions in the upper atmosphere, which naturally generate muons as they descend to Earth; harnessing these muons, however, is tedious and not very practical, with days or months needed to capture enough muon data to produce meaningful results. Muons can also be generated terrestrially, but this technique such high-energy particles that production is limited to large physics research facilities such as the Fermilab national particle accelerator in Illinois and the European CERN accelerator in Switzerland.

Mark Wrobel, MuS2 program manager in DARPA’s Defense Sciences Office, says of the project: “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. 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. MuS2 will lay the ground work needed to examine the feasibility of developing compact and transportable muon sources.”

MuS2 aims to use 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 -- and ultimateley develop scalable and practical processes to produce conditions that can create muons exceeding 100 GeV through innovations in LPA, target design, and compact laser driver technology. The agency's hope is that if MuS2 and any follow-on efforts are successful, entire buildings could be scanned from the outside to characterize internal structures and detect the presence of threat materials such as special nuclear materials, or users could rapidly map the location of underground tunnels and chambers hundreds of meters below the Earth’s surface.

The four-year MuS2 program is divided into two phases: The 24-month-long initial phase will see teams conduct modeling and scaling studies, run experiments to validate models, and attempt to produce 10 GeV muons. In the second 24-month phase, teams will aim to develop scalable accelerator designs for 100 GeV or greater and produce relevant numbers of muons for practical applications.

DARPA will hold an online Proposers' Day on August 5, 2022 (click here for detalis).

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