Assistant Professor of Nuclear Science and Engineering
In its list of Grand Engineering Challenges for 21st century, the National Academy of Engineering lists Nuclear Security, along with developing fusion energy, among its fourteen challenges. If the peaceful use of fission energy is to continue taking place, then we are faced with issues of proliferation and arms control. Nuclear Security is a broad field, which includes: active and passive interrogation of commercial cargoes and public areas, with the aim of preventing nuclear terrorism; nuclear safeguards; nuclear nonproliferation; treaty verification andarms controls.
A common method of inspecting commercial cargoes for the presence of fissile materials involves the use of 1-10MeV bremsstrahlung photon beams. While simple and reliable, this technique has many downsides, such as the large doses involved and its relative inefficiency at triggering NRF and photofission. Much progress in the field of active interrogation can be achieved by developing monochromatic, and possibly tunable gamma sources:
Currently, a collaboration lead by MIT is exploring the possibility of using proton and deuteron beams in 11B(d,nγ)12C and 12C(p,p’γ)12C reactions, which produce highly monochromatic photons.This program makes use of a 3MeV deuteron source at MIT-Bates linear accelerator to experiment with (d,nγ) reactions. This approach can be used not only to achieve low dose radiography, but also low dose dual energy radiography and lower dose photofission for fissionable material detection.
Arms reduction is an important part of improving global security. The New START treaty limits the number of warheads to 1550. The participant states will then be required to demonstrate compliance, while retaining the secrecy of weapons’ design. This will involve proving to an inspection crew that the warheads being destroyed are real, without releasing any direct nuclear or physical information about the weapon structure. Zero knowledge detectors have been proposed to solve this puzzle. The zero knowledge proof is an abstract concept, which answers a simple yes/no question without revealing any additional information. Various zero knowledge detection concepts have been proposed. These include the use of neutron radiography, as well as reference foil NRF measurements. The reference foil in this case will produce an NRF signal, which is a convolution of the weapon’s and reference foil’s isotopic makeup. This data is then compared to that from measurements taken on a warhead of known authenticity. This comparison tests the hypothesis that the two weapons are identical. A successful test will help verify the authenticity of the first weapon. Additionally, other concepts of zero knowledge detection are being studied and considered.
“Photon Induced Neutron Time Correlations in Special Nuclear Materials,” ROI submitted
D.J. Hamilton, A. Shahinyan et al., “An electromagnetic calorimeter for the JLab real Compton scattering experiment,” Nuclear Instruments and Methods, Vol. 643, Issue 1, 1 July 2011, pp. 17-28.
A. Danagoulian, W. Bertozzi et al., “Prompt neutrons from photofission and its use in homeland security applications,” 2010 IEEE International Conference on Technologies for Homeland Security, pp. 379-384, (2010).
M. Sharma et al., “Neutron Beam Effects on Spin-Exchange-Polarized 3He,” Physical Review Letters, Vol 101, 083002 (2008).
A. Danagoulian et al.,“Compton Scattering Cross Section on the Proton at High Momentum Transfer”, Phys. Rev. Letters, Vol. 98, 152001 (2007).
D.J. Hamilton et al., “Polarization Transfer in Proton Compton Scattering at High Momentum transfer,” Phys. Rev. Letters, Vol. 94, 242001 (2005).
T. M. Ito et al., “Parity-Violating Electron Deuteron Scattering and the Proton’s Neutral Weak Axial Vector Form Factor,” Phys. Rev. Letters, Vol. 92, 102003 (2004).
R. Hasty et al.,“Strange Magnetism and the Anapole Structure of the Proton,” Science, Vol. 290 (2000), pp. 2117-2119.
22.09 Principles of Nuclear Radiation Measurement & Protection