• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2909-2917
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• 2021

Following the launch of Rare Isotope Science Project in December 2011, a heavy ion accelerator complex in South Korea, named RAON, has since been designed. It includes a muon facility for muon spin rotation, relaxation, and resonance. The facility will be provided with 600 MeV and 100 kW (one-fourth of the maximum power) proton beam. In this study, the graphite target in RAON was designed to have a rotating disk shape and was cooled by radiative heat transfer. This cool-down process has the following advantages: a low-temperature gradient in the target and the absence of a liquid coolant cooling system. Monte Carlo simulations and ANSYS calculations were performed to optimize the target system in a thermally stable condition when the 100 kW proton beam collided with the target. A comparison between the simulation and experimental data was also included in the design process to obtain reliable results. The final design of the target system will be completed within 2020, and its manufacturing is in progress. The manufactured target system will be installed at the RAON in the Sindong area near Daejeon-city in 2021 to carry out verification experiments.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3344-3351
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• 2021

The Rare Isotope Science Project was launched in 2011 in Korea toward constructing the Rare isotope Accelerator complex for ON line experiments (RAON). RAON will house several experimental systems, including the Muon Spin Rotation/Relaxation/Resonance (μSR) facility in High Energy Experimental Building B. This facility will use 600-MeV protons with a maximum current of 660 pμA and beam power of 400 kW. The key μSR features will facilitate projects related to condensed-matter and nuclear physics. Typical experiments require a few million surface muons fully spin-polarized opposite to their momentum for application to small samples. Here, we describe the design of a muon transport beam line for delivering the requisite muon numbers and the electromagnetic-component specifications in the μSR facility. We determine the beam-line configuration via beam-optics calculations and the transmission efficiency via single-particle tracking simulations. The electromagnet properties, including fringe field effects, are applied for each component in the calculations. The designed surface-muon beamline is 17.3 m long, consisting of 2 solenoids, 2 dipoles affording 70° deflection, 9 quadrupoles, and a Wien filter to eliminate contaminant positrons. The average incident-muon flux and spin rotation angle are estimated as 5.2 × 10⁶ μ⁺/s and 45°, respectively.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3768-3774
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• 2023

The purpose of the target system for the muon spin rotation, relaxation, and resonance (µSR) facility at the Rare isotope Accelerator complex for ON-line experiments (RAON) is to induce the production of a significant number of surface muons in thermally stable experiments. The manufactured target system was installed at RAON in the Sindong area near Daejeon in 2021. The design was made conservatively with a sufficient margin of safety through ANSYS calculations; however, verification experiments had to be performed on the ANSYS calculations. Because the 600-MeV proton beam has not yet been provided, an alternative way to reproduce the calculation conditions was required. The radio frequency (RF) heating method, which has not yet been applied to the target verification experiment but has several advantages, was used. It was observed that the RF heating method has promise for testing the thermal stability of the target, and whether the target system design process was performed conservatively enough was verified by comparing the RF heating experiments with the ANSYS calculations.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3692-3699
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• 2023

The Rare isotope Accelerator complex for ON-line experiments in Korea houses several accelerator complexes. Among them, the µSR facility will be initially equipped with a 600 MeV and 100 kW proton beam to generate surface muons, and will be upgraded to 400 kW with the same energy. Accelerated proton beams lose approximately 20% of the power at the target, and the remaining power is concentrated in the beam direction. Therefore, to ensure safe operation of the facility, concentrated protons must be distributed and absorbed at the beam dump. Additionally, effective dose levels must be lower than the legal standard, and the beam dumps used at 100 kW should be reused at 400 kW to minimize the generation of radioactive waste. In this study, we introduce a tailored method for designing beam dumps based on the characteristics of the µSR facility. To optimize the geometry, the absorbed power and effective dose were calculated using the MCNP6 code. The temperature and stress were determined using the ANSYS Mechanical code. Thus, the beam dump design consists of six structures when operated at 100 kW, and a 400 kW beam dump consisting of 24 structures was developed by reusing the 100 kW beam dump.