A novel compact high-flux neutron generator with a pitcher-catcher configuration based on laser-driven collisionless shock acceleration (CSA) is proposed and experimentally verified. Different from those that previously relied on target normal sheath acceleration (TNSA), CSA in nature favors not only acceleration of deuterons (instead of hydrogen contaminants) but also increasing of the number of deuterons in the high-energy range, therefore having great advantages for production of high-flux neutron source. The proof-of-principle experiment has observed a typical CSA plateau feature from 2 to 6 MeV in deuteron energy spectrum and measured a forward neutron flux with yield 6.6×10^{7} n/sr from the LiF catcher target, an order of magnitude higher than the compared TNSA case, where the laser intensity is 10^{19} W/cm^{2}. Self-consistent simulations have reproduced the experimental results and predicted that a high-flux forward neutron source with yield up to 5×10^{10} n/sr can be obtained when laser intensity increases to 10^{21} W/cm^{2} under the same laser energy.
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http://dx.doi.org/10.1103/PhysRevLett.131.025101 | DOI Listing |
Rev Sci Instrum
October 2024
Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Neutron measurement is the primary tool in the SPARC tokamak for fusion power (Pfus) monitoring, research on the physics of burning plasmas, validation of the neutronics simulation workflows, and providing feedback for machine protection. A demanding target uncertainty (10% for Pfus) and coverage of a wide dynamic range (>8 orders of magnitude going up to 5 × 1019 n/s), coupled with a fast-track timeline for design and deployment, make the development of the SPARC neutron diagnostics challenging. Four subsystems are under design that exploit the high flux of direct DT and DD plasma neutrons emanating from a shielded opening in a midplane diagnostic port.
View Article and Find Full Text PDFSci Rep
September 2024
Department of Atomic, Molecular and Nuclear Physics, Universidad de Granada, 18072, Granada, Spain.
Boron Neutron Capture Therapy (BNCT) is performed using high-intensity neutron sources; however, the energy of the primary neutrons is too high for direct patient irradiation. Thus, neutron moderation is mandatory and is performed using a device known as a Beam Shaping Assembly (BSA). Due to the differences in flux and energy spectra between neutron sources, each facility needs a dedicated BSA design, whether it is based on a nuclear reactor or, more recently, on an accelerator.
View Article and Find Full Text PDFPhys Rev Lett
August 2024
European Organization for Nuclear Research (CERN), Switzerland.
Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the r-process contribution by their stable isobars are defined as s-only nuclei. For a long time the abundance of ^{204}Pb, the heaviest s-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance.
View Article and Find Full Text PDFJ Phys Chem B
June 2024
Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, United States.
Herein, we employed high-flux backscattering spectroscopy to capture for the first time the motions of hydrated vanadyl ions in ionomer nanocomposites prepared by both solution-cast and sol-gel condensation methods. Both local and jump diffusion coefficients of the hydrated vanadyl (VO) ions as well as the dynamic length scales of ion motions and the fraction of immobile hydrogen atoms were extracted from the scattering spectra. Notably, for solution-cast membranes, the jump and local diffusion coefficients of hydrated VO ions were seen to decrease by over 10- and 4-fold, respectively, with the introduction of 10 mass % silica nanoparticles (SiNPs) compared to their neat counterparts.
View Article and Find Full Text PDFRev Sci Instrum
May 2024
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
The neutron sources at Oak Ridge National Laboratory use a wide suite of sample environment equipment to deliver extreme conditions for a number of experiments. Much of this instrumentation focuses on extremes of temperature, such as cryostats, closed-cycle refrigerators in both low and high temperature configurations, and radiant heating furnaces. When the temperature is controlled across a large range, thermal deflection effects can notably move the sample and affect its alignment in the beam.
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