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| MOPOB13 | Post Irradiation Examination Results of the NT-02 Graphite Fins Numi Target | 99 |
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Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The NT-02 neutrino target in the NuMI beamline at Fermilab is a 95 cm long target made up of segmented graphite fins. It is the longest running NuMI target, which operated with a 120 GeV proton beam with maximum power of 340 kW, and saw an integrated total proton on target of 6.1 x 1020. Over the last half of its life, gradual degradation of neutrino yield was observed until the target was replaced. The probable causes for the target performance degradation are attributed to radiation damage, possibly including cracking caused by reduction in thermal shock resistance, as well as potential localized oxidation in the heated region of the target. Understanding the long-term structural response of target materials exposed to proton irradiation is critical as future proton accelerator sources are becoming increasingly more powerful. As a result, an autopsy of the target was carried out to facilitate post-irradiation examination of selected graphite fins. Advanced microstructural imaging and surface elemental analysis techniques were used to characterize the condition of the fins in an effort to identify degradation mechanisms, and the relevant findings are presented in this paper. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB13 | |
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| MOPOB14 | Experimental Results of Beryllium Exposed to Intense High Energy Proton Beam Pulses | 102 |
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Funding: Work supported by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Beryllium is extensively used in various accelerator beam lines and target facilities as material for beam windows, and to a lesser extent, as secondary particle production targets. With increasing beam intensities of future accelerator facilities, it is critical to understand the response of beryllium under extreme conditions to reliably operate these components as well as avoid compromising particle production efficiency by limiting beam parameters. As a result, an exploratory experiment at CERN's HiRadMat facility was carried out to take advantage of the test facility's tunable high intensity proton beam to probe and investigate the damage mechanisms of several beryllium grades. The test matrix consisted of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. This paper outlines the experimental measurements, as well as findings from Post-Irradiation-Examination (PIE) work where different imaging techniques were used to analyze and compare surface evolution and microstructural response of the test matrix specimens. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB14 | |
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| MOPOB35 | Design of the LBNF Beamline Target Station | 146 |
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Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The Long Baseline Neutrino Facility (LBNF) project will build a beamline located at Fermilab to create and aim an intense neutrino beam of appropriate energy range toward the DUNE detectors at the SURF facility in Lead, South Dakota. Neutrino production starts in the Target Station, which consists of a solid target, magnetic focusing horns, and the associated sub-systems and shielding infrastructure. Protons hit the target producing mesons which are then focused by the horns into a helium-filled decay pipe where they decay into muons and neutrinos. The target and horns are encased in actively cooled steel and concrete shielding in a chamber called the target chase. The reference design chase is filled with air, but nitrogen and helium are being evaluated as alternatives. A replaceable beam window separates the decay pipe from the target chase. The facility is designed for initial operation at 1.2 MW, with the ability to upgrade to 2.4 MW, and is taking advantage of the experience gained by operating Fermilab's NuMI facility. We discuss here the design status, associated challenges, and ongoing R&D and physics-driven component optimization of the Target Station. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB35 | |
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