beecee Posted August 7, 2018 Posted August 7, 2018 https://phys.org/news/2018-08-renovations-big-nuclear-astrophysics-lab.html In nature, the nuclear reactions that form stars are often accompanied by astronomically high amounts of energy, sometimes over billions of years. This presents a challenge for nuclear astrophysicists trying to study these reactions in a controlled, low-energy laboratory setting. The chances of re-creating such a spark without bombarding targets with high-intensity beams are unfathomably low. However, after recent renovations to its accelerator, one laboratory reported record-breaking performance. Following six years of upgrades to the Electron Cyclotron Resonance Ion Source (ECRIS) at the Laboratory for Experimental Nuclear Astrophysics, a member of the Triangle Universities Nuclear Laboratory, researchers from the University of North Carolina report improved results. In Review of Scientific Instruments, the group focused on the system's acceleration column and microwave system, making it safer and yielding better high-voltage source stability and signal-to-background ratio. "What a lot of people don't realize is that there isn't really anything that exists on the market for this that we can just buy," said Andrew Cooper, an author on the paper and one of the lead designers behind the project. "Rather than pay millions of dollars [for upgrades], we approached it as a challenge." Read more at: https://phys.org/news/2018-08-renovations-big-nuclear-astrophysics-lab.html#jCp the paper: https://aip.scitation.org/doi/10.1063/1.5024938 Development of a variable-energy, high-intensity, pulsed-mode ion source for low-energy nuclear astrophysics studies: ABSTRACT: The primary challenge in directly measuring nuclear reaction rates near stellar energies is their small cross sections. The signal-to-background ratio in these complex experiments can be significantly improved by employing high-current (mA-range) beams and novel detection techniques. Therefore, the electron cyclotron resonance ion source at the Laboratory for Experimental Nuclear Astrophysics underwent a complete upgrade of its acceleration column and microwave system to obtain high-intensity, pulsed proton beams. The new column uses a compression design with O-ring seals for vacuum integrity. Its voltage gradient between electrode sections is produced by the parallel resistance of channels of chilled, deionized water. It also incorporates alternating, transverse magnetic fields for electron suppression and an axially adjustable beam extraction system. Following this upgrade, the operational bremsstrahlung radiation levels and high-voltage stability of the source were vastly improved, over 3.5 mA of target beam current was achieved, and an order-of-magnitude increase in normalized brightness was measured. Beam optics calculations, structural design, and further performance results for this source are presented.
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