We review the potential to develop sources for neutron scattering science and propose that a merger with the rapidly developing field of inertial fusion energy could provide a major step-change in performance. In stark contrast to developments in synchrotron and laser science, the past 40 years have seen only a factor of 10 increase in neutron source brightness. With the advent of thermonuclear ignition in the laboratory, coupled to innovative approaches in how this may be achieved, we calculate that a neutron source three orders of magnitude more powerful than any existing facility can be envisaged on a 20- to 30-year time scale. Such a leap in source power would transform neutron scattering science.
"In order to generate high neutron fluxes to accommodate more scientific applications, high-power spallation sources, such as the ISIS, J-PARC, and SNS facilities have been realized . An even more powerful source, the European Spallation Source (ESS), is currently under study . However, since the primary mission of the high-power neutron sources is to serve a large number of users for materials characterization, it is not cost-effective to use such expensive facilities for education and training or for evaluation of instrumentation ideas . "
[Show abstract][Hide abstract] ABSTRACT: A simple and easy-to-use compact neutron source based on a low power level proton accelerator (proton energy 3.5 MeV and 0.35 kW beam power) at Kyoto University was designed with the conception of low cost, compact size, high safety and intensive thermal neutron flux via Monte Carlo method with PHITS code. By utilizing (p, n) reactions in a beryllium target coupled to a polyethylene moderator and graphite reflector with a wing configuration, this facility is expected to produce time-averaged thermal neutron fluxes suitable for neutron scattering and development of instrumentation, and play a role in educating students in neutron science and performing research with neutrons. Borated polyethylene (BPE) and ordinary concrete were combined to shield the neutron and photon. By using niobium as target backing and water as cooler, it is promising to cope with the problem of thermal damage and hydrogen embrittlement damage. The sizes of moderator and reflector are optimized to have thermal neutron flux as high as possible, while keeping the low ratio of fast neutron flux to thermal neutron flux. The neutron and gamma dose equivalent rates were evaluated and the current shielding configuration is acceptable.
"The total power of 1 MW released in a D-T fusion reaction corresponds to 14.1 MeV neutron production rate of 3.55×10 s) in pulse mode are produced in spallation sources . Such a level of intensity and flux density of neutrons can be attained or even exceeded on the basis of either D-T and D-D fusion reactions in SS-operating tokamaks  or inertial fusion systems operating in periodic pulse mode with a few tens of Hertz frequency . "
[Show abstract][Hide abstract] ABSTRACT: Tokamak-based MW-range fusion neutron sources are needed for the development of innovative neutron technologies, mainly for the control of sub-critical active zones of fast nuclear reactors, for closing the nuclear fuel cycle, for neutron research purposes and also for nuclear technologies relevant to DEMO. In this paper a possibility of reducing the tokamak size while achieving steady-state plasma discharges with the fusion power up to 10 MW is discussed. It is assumed that the total auxiliary heating and current drive power does not exceed 15 MW and the total power consumption is below 30 MW. The possible parameter options and operation scenarios are described.
[Show abstract][Hide abstract] ABSTRACT: Crystallography supplies unparalleled detail on structural information critical for mechanistic analyses; however, it is restricted to describing low energy conformations of macromolecules within crystal lattices. Small angle X-ray scattering (SAXS) offers complementary information about macromolecular folding, unfolding, aggregation, extended conformations, flexibly linked domains, shape, conformation, and assembly state in solution, albeit at the lower resolution range of about 50 A to 10 A resolution, but without the size limitations inherent in NMR and electron microscopy studies. Together these techniques can allow multi-scale modeling to create complete and accurate images of macromolecules for modeling allosteric mechanisms, supramolecular complexes, and dynamic molecular machines acting in diverse processes ranging from eukaryotic DNA replication, recombination and repair to microbial membrane secretion and assembly systems. This review addresses both theoretical and practical concepts, concerns and considerations for using these techniques in conjunction with computational methods to productively combine solution scattering data with high-resolution structures. Detailed aspects of SAXS experimental results are considered with a focus on data interpretation tools suitable to model protein and nucleic acid macromolecular structures, including membrane protein, RNA, DNA, and protein-nucleic acid complexes. The methods discussed provide the basis to examine molecular interactions in solution and to study macromolecular flexibility and conformational changes that have become increasingly relevant for accurate understanding, simulation, and prediction of mechanisms in structural cell biology and nanotechnology.
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