LANL, Los Alamos, New Mexico
For national security, it is important to detect the presence of Special Nuclear Materials (SNM), especially Highly-Enriched Uranium (HEU). Generally used methods for such detection include interrogation by photons and neutrons. For example, photofission in HEU can be initiated with 14-MeV photons. The resulting delayed neutrons and photons from the fission fragments are clear signatures of the presence of HEU. One can generate high-energy photons using electron accelerators via various mechanisms. In this paper, we will describe two of them, namely electron bremsstrahlung and Compton-backscattered photons. We focus on these two mechanisms because they cover a wide range of accelerator requirements. Electron bremsstrahlung can be generated using a compact low-energy electron linac while the generation of Compton-backscattered photons requires a high-energy electron accelerator of a few hundred MeV. We review these two options, describe their accelerator requirements, and compare their relative merits.
LLNL, Livermore, California
PPPL, Princeton, New Jersey
LBNL, Berkeley, California
University of electro-communications, Tokyo
We describe near term heavy-ion beam-driven warm dense matter (WDM) experiments. Initial experiments are at low beam velocity, below the Bragg peak, increasing toward the Bragg peak in subsequent versions of the accelerator. The WDM conditions are envisioned to be achieved by combined longitudinal and transverse neutralized drift compression to provide a hot spot on the target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using porous targets at reduced density. Initial candidate experiments include an experiment to study transient darkening in the WDM regime; and a thin target dE/dx experiment to study beam energy and charge state distribution in a heated target. Further experiments will explore target temperature and other properties such as electrical conductivity to investigate phase transitions and the critical point.