Areg Danagoulian

Physical cryptographic verification of nuclear warheads

Significance We provide a method for potentially solving one of the central problems in arms control: proving the authenticity of a nuclear warhead without revealing information about its construction. The proposal is the first, to our knowledge, to be proof-theoretically sound (i.e., unspoofable) and information-theoretically secure. The method uses a tomography technique which can resolve the spatial distribution of mass with isotopic specificity. The soundness and security emerge from an integral-geometric transform that is able to uniquely map 3D geometries from zero-dimensional point measurements. How does one prove a claim about a highly sensitive object such as a nuclear weapon without revealing information about the object? This paradox has challenged nuclear arms control for more than five decades. We present a mechanism in the form of an interactive proof system that can validate the structure and composition of an object, such as a nuclear warhead, to arbitrary precision without revealing either its structure or composition. We introduce a tomographic method that simultaneously resolves both the geometric and isotopic makeup of an object. We also introduce a method of protecting information using a provably secure cryptographic hash that does not rely on electronics or software. These techniques, when combined with a suitable protocol, constitute an interactive proof system that could reject hoax items and clear authentic warheads with excellent sensitivity in reasonably short measurement times.

Experimental demonstration of an isotope-sensitive warhead verification technique using nuclear resonance fluorescence

Significance We present an experimental demonstration of an isotope-sensitive warhead verification protocol. The measurement is capable of detecting tampering with a warhead’s material or geometry with high statistical confidence in realistically attainable measurement times, while simultaneously protecting sensitive warhead design information. Such a protocol could enable the verifiable elimination of nuclear warheads under a future arms reduction treaty. Future nuclear arms reduction efforts will require technologies to verify that warheads slated for dismantlement are authentic without revealing any sensitive weapons design information to international inspectors. Despite several decades of research, no technology has met these requirements simultaneously. Recent work by Kemp et al. [Kemp RS, Danagoulian A, Macdonald RR, Vavrek JR (2016) Proc Natl Acad Sci USA 113:8618–8623] has produced a novel physical cryptographic verification protocol that approaches this treaty verification problem by exploiting the isotope-specific nature of nuclear resonance fluorescence (NRF) measurements to verify the authenticity of a warhead. To protect sensitive information, the NRF signal from the warhead is convolved with that of an encryption foil that contains key warhead isotopes in amounts unknown to the inspector. The convolved spectrum from a candidate warhead is statistically compared against that from an authenticated template warhead to determine whether the candidate itself is authentic. Here we report on recent proof-of-concept warhead verification experiments conducted at the Massachusetts Institute of Technology. Using high-purity germanium (HPGe) detectors, we measured NRF spectra from the interrogation of proxy “genuine” and “hoax” objects by a 2.52 MeV endpoint bremsstrahlung beam. The observed differences in NRF intensities near 2.2 MeV indicate that the physical cryptographic protocol can distinguish between proxy genuine and hoax objects with high confidence in realistic measurement times.

Nuclear disarmament verification via resonant phenomena

Nuclear disarmament treaties are not sufficient in and of themselves to neutralize the existential threat of the nuclear weapons. Technologies are necessary for verifying the authenticity of the nuclear warheads undergoing dismantlement before counting them toward a treaty partner’s obligation. Here we present a concept that leverages isotope-specific nuclear resonance phenomena to authenticate a warhead’s fissile components by comparing them to a previously authenticated template. All information is encrypted in the physical domain in a manner that amounts to a physical zero-knowledge proof system. Using Monte Carlo simulations, the system is shown to reveal no isotopic or geometric information about the weapon, while readily detecting hoaxing attempts. This nuclear technique can dramatically increase the reach and trustworthiness of future nuclear disarmament treaties.Authenticating a nuclear warhead without revealing its design is a challenge. Here the authors discuss a nuclear disarmament verification method based on neutron resonance analysis which is sensitive to the isotopic composition of the materials used in warheads.

High-accuracy Geant4 simulation and semi-analytical modeling of nuclear resonance fluorescence

Abstract Nuclear resonance fluorescence (NRF) is a photonuclear interaction that enables highly isotope-specific measurements in both pure and applied physics scenarios. High-accuracy design and analysis of NRF measurements in complex geometries is aided by Monte Carlo simulations of photon physics and transport, motivating Jordan and Warren (2007) to develop the G4NRF codebase for NRF simulation in Geant4. In this work, we enhance the physics accuracy of the G4NRF code and perform improved benchmarking simulations. The NRF cross section calculation in G4NRF, previously a Gaussian approximation, has been replaced with a full numerical integration for improved accuracy in thick-target scenarios. A high-accuracy semi-analytical model of expected NRF count rates in a typical NRF measurement is then constructed and compared against G4NRF simulations for both simple homogeneous and more complex heterogeneous geometries. Agreement between rates predicted by the semi-analytical model and G4NRF simulation is found at a level of ∼ 1 % in simple test cases and ∼ 3 % in more realistic scenarios, improving upon the ∼ 20 % level of the initial benchmarking study and establishing a highly-accurate NRF framework for Geant4.

Experimental demonstration of multiple monoenergetic gamma radiography for effective atomic number identification in cargo inspection

The smuggling of special nuclear materials (SNM) through international borders could enable nuclear terrorism and constitutes a significant threat to global security. This paper presents the experimental demonstration of a novel radiographic technique for inferring the density and type of material present in commercial cargo containers, as a means of detecting such threats. Unlike traditional techniques which use sources of bremsstrahlung photons with a continuous distribution of energies, this technique utilizes monoenergetic photons from nuclear reactions, specifically the 4.4 and 15.1 MeV photons from the

Spectroscopic neutron radiography for a cargo scanning system

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Initial results from a multiple monoenergetic gamma radiography system for nuclear security

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