The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT...The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT/T3He yield ratio is∼23lower than expected from temperature scaling.InD3He-gas-filled(with trace T)shock-driven implosions,the timing of theD3He reaction history is∼50 ps earlier than those of the DT reaction histories,and average-ion hydrodynamic simulations cannot reconcile this timing difference.Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.展开更多
Nuclear nonproliferation is of critical importance for global security.Dangerous fissile materials including highly enriched uranium and weapons-grade plutonium are especially important to detect.Active interrogation ...Nuclear nonproliferation is of critical importance for global security.Dangerous fissile materials including highly enriched uranium and weapons-grade plutonium are especially important to detect.Active interrogation techniques may result in much better sensitivity but are difficult with conventional portal monitors that rely on detecting thermal neutrons.Also,most conventional portal monitoring systems rely on ^(3)He,which has a finite and continually decreasing supply.By designing a highly segmented array of organic scintillators,we posit that we can accurately and quickly identify fissile materials,including weapons-grade plutonium and highly enriched uranium,being smuggled.We propose a new design for a fast-neutron detector that overcomes the limitations of the current generation of portal monitors.MCNP6 simulations have been performed in conjunction with the UMPBT statistical model to determine the sensitivity limitations of the proposed detector.Results suggest that the proposed detector may be 10 times more efficient than current-generation thermal neutron detectors and may be able to positively identify a 81 mg 235U source in as little as 192 seconds utilizing active interrogation techniques.展开更多
基金This material is based upon work supported by the Department of Energy,National Nuclear Security Administration under Award Nos.DE-NA0001857,DE-NA0002949,and DENA0002905.The work was also supported in part by NLUF(DE-NA0002035).H.S.was supported by a DOE NNSA SSGF Fellowship(DE-FC52-08NA28752)during this work.S.A.acknowledges Sapienza Project 2016 No.RM11615502006B04,as well as EUROfusion Project Nos.AWP17-ENR-IFE-CEA-01 and ENR-IFE19.CEA-01.A.L.acknowledges the LANL LDRD program.
文摘The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT/T3He yield ratio is∼23lower than expected from temperature scaling.InD3He-gas-filled(with trace T)shock-driven implosions,the timing of theD3He reaction history is∼50 ps earlier than those of the DT reaction histories,and average-ion hydrodynamic simulations cannot reconcile this timing difference.Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.
基金supported by the National Nuclear Security Administration(NNSA)through the Center for Excellence in Nuclear Training and University Based Research(CENTAUR)under Award No.DE-NA0003841by the U.S.Department of Energy,Office of Science,Office of Nuclear Physics,under Award No.DE-FG02-93ER40773the College of Science at Texas A&M University through Strategic Transformative Research Program(CoS STRP).
文摘Nuclear nonproliferation is of critical importance for global security.Dangerous fissile materials including highly enriched uranium and weapons-grade plutonium are especially important to detect.Active interrogation techniques may result in much better sensitivity but are difficult with conventional portal monitors that rely on detecting thermal neutrons.Also,most conventional portal monitoring systems rely on ^(3)He,which has a finite and continually decreasing supply.By designing a highly segmented array of organic scintillators,we posit that we can accurately and quickly identify fissile materials,including weapons-grade plutonium and highly enriched uranium,being smuggled.We propose a new design for a fast-neutron detector that overcomes the limitations of the current generation of portal monitors.MCNP6 simulations have been performed in conjunction with the UMPBT statistical model to determine the sensitivity limitations of the proposed detector.Results suggest that the proposed detector may be 10 times more efficient than current-generation thermal neutron detectors and may be able to positively identify a 81 mg 235U source in as little as 192 seconds utilizing active interrogation techniques.
