International Defense Security & Technology Your trusted Source for News, Research and Analysis
Related Articles
DARPA’s “Decay on Demand”: Engineering Nuclear Decay with Laser Precision
DARPA is pioneering laser-driven nuclear control to accelerate isotope decay — a breakthrough that could revolutionize medicine, space power, and defense technology.
The Defense Advanced Research Projects Agency (DARPA) has always stood at the frontier of scientific disruption, and its latest endeavor under the Defense Sciences Office (DSO) continues that legacy. This ambitious program, announced in draft form in June 2024, seeks to fundamentally transform our ability to access valuable radioactive isotopes by artificially accelerating their natural decay processes. By developing methods to induce alpha decay on command, DARPA aims to solve a critical bottleneck in nuclear science and open new possibilities across medicine, energy production, and industrial applications
The Radioisotope Accessibility Problem
The Earth is rich in actinide radioisotopes—elements like uranium, thorium, and actinium. While many of these parent isotopes are long-lived, their decay chains produce daughter isotopes that are far more useful for high-impact applications. Unfortunately, the natural half-lives of these decay processes can span thousands to billions of years, making it virtually impossible to generate usable quantities in any reasonable timeframe.
At the heart of this challenge lies a fundamental limitation of nuclear physics. Many of the most useful radioactive isotopes exist in decay chains with impractically long half-lives, essentially locking away their potential benefits. Thorium-232, for instance, possesses remarkable potential for radioisotope power systems with 10 to 100 times greater power density than current plutonium-based systems. However, its natural decay to the useful thorium-228 isotope takes an astronomical 14 billion years.
The medical field faces similar constraints with actinium-225, a rare isotope showing tremendous promise for targeted alpha therapy in cancer treatment. This valuable medical isotope forms part of the uranium-233 decay chain, which proceeds at a geological pace with a 159,000-year half-life. Current production methods using nuclear reactors, cyclotrons, and particle accelerators struggle to meet demand, with global production of actinium-225 amounting to barely a few milligrams annually – equivalent to just a few grains of sand.
The DARPA Vision: Triggering Nuclear Decay on Command
DARPA’s Decay on Demand initiative envisions a future where scientists can deliberately induce alpha decay, converting parent isotopes into their useful daughters with precision and efficiency. The agency is seeking researchers to propose experimental or theoretical approaches that will transform how alpha-emitting radioisotopes are harvested.
DARPA’s solution involves developing precise methods to increase energy absorption in radioisotopes, thereby inducing the emission of alpha particles and converting significant quantities of parent isotopes into their daughter products. The agency is specifically focusing on techniques that induce alpha-particle emission while explicitly excluding fission-based methods or approaches that produce multiple neutron emissions.
DARPA’s solicitation builds on recent experimental breakthroughs that suggest the potential to circumvent natural decay using commercially available lasers and electronic methods. Recent experiments have shown promising results using commercially available lasers to manipulate nuclear decay processes. These studies suggest it may be possible to overcome the strong nuclear force binding neutrons and protons together, or alternatively increase the transparency of the Coulomb barrier – the electrostatic force that normally prevents charged particles from escaping the nucleus. By employing electronic methods to reduce this barrier, researchers have demonstrated the potential to significantly increase the probability of alpha particle emission on timescales far shorter than natural radioactive half-lives.
In short, science may now be on the brink of engineering nuclear decay—a feat once considered impossible outside of high-energy nuclear reactors or accelerators.
Program Structure: Dual Tracks, Collaborative Focus
The Decay on Demand program offers two concurrent research tracks, each lasting two years and comprising two phases.
Track 1 focuses on experimental approaches, with researchers conducting hands-on investigations to generate empirical data about emissions spectroscopy across different radioisotope species. This track offers up to $2 million in funding across two phases: Phase 1 will involve feasibility studies using emissions spectroscopy to generate data on different radioisotope species. Phase 2 will refine techniques that show promise for scalable alpha decay induction. The total funding available for Track 1 across both phases is up to $2 million.
Track 2 takes a theoretical approach, with researchers analyzing experimental results to develop comprehensive physical models of the decay acceleration process. This track explores fundamental mechanisms such as photon-induced alpha emission and electroweak methods, with up to $1 million available for exploratory theoretical analyses in phase 1 and theory establishment in phase 2. Research teams may submit proposals for either or both tracks, though each requires a separate submission.
A key requirement of the program is complete data sharing among all participants. All experimental results, analytic products, simulations, and calculations must be made available to other performers, fostering collaboration and accelerating progress. Decisions about which projects advance to phase 2 will be based entirely on the scientific merit and results demonstrated in phase 1.
Transformative Potential Applications
Success in the Decay on Demand program could revolutionize several critical fields. In medicine, reliable access to actinium-225 could transform cancer treatment through targeted alpha therapy, which delivers potent radiation directly to tumor cells while minimizing damage to healthy tissue. The current extreme scarcity of this isotope severely limits clinical applications despite its remarkable therapeutic potential.
For power systems, it could revolutionize compact nuclear batteries for deep-space missions or remote military applications by harnessing high-energy isotopes like thorium-228. In industrial settings, it could support emerging technologies requiring rare radioactive tracers or heat sources.
Thorium-derived isotopes could enable a new generation of radioisotope power systems with dramatically improved energy density, potentially powering deep space missions or remote sensors for years without maintenance. More broadly, the ability to produce rare isotopes on demand could eliminate dependence on nuclear reactors and particle accelerators for many applications
Technical and Ethical Considerations
While the scientific promise is compelling, significant challenges remain. Researchers must demonstrate precise control over decay processes without triggering unwanted nuclear reactions. The technology must prove both scalable and economically viable for practical applications. Additionally, DARPA recognizes the need to address potential security concerns and ethical implications surrounding controlled manipulation of nuclear materials.
The program explicitly excludes fission-based approaches and methods producing multiple neutrons, reflecting careful consideration of safety and non-proliferation concerns. As research progresses, DARPA plans to engage with the broader scientific community and policymakers to ensure responsible development of any resulting technologies.
Conclusion: Engineering the Unthinkable
With Decay on Demand, DARPA is challenging the scientific community to rethink the immutability of nuclear decay. The Decay on Demand program represents more than just another research initiative – it aims to fundamentally alter our relationship with radioactive materials by giving us unprecedented control over their transformation.
If successful, this program could mark the beginning of a new era in nuclear science—where human ingenuity accelerates atomic transformation, bringing once-inaccessible resources to the forefront of innovation.
Should this effort succeed, it could mark the beginning of a new era in nuclear science, with implications ranging from life-saving medical treatments to revolutionary power sources for space exploration. By breaking through the time barriers imposed by natural decay processes, humanity might gain access to an entirely new toolkit of nuclear materials and applications.
