Optimizing neutron moderators for a spallation-driven ultracold-neutron source at TRIUMF
| Autor: | T. Kikawa, C. Marshall, W. Schreyer, R. Picker, Takahiro Okamura, Kenji Mishima, C. A. Davis, Shinsuke Kawasaki |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Accelerator Physics (physics.acc-ph)
Nuclear and High Energy Physics Physics - Instrumentation and Detectors Nuclear engineering Cyclotron FOS: Physical sciences chemistry.chemical_element 01 natural sciences 7. Clean energy law.invention law 0103 physical sciences Neutron Spallation Physics::Atomic Physics Nuclear Experiment (nucl-ex) 010306 general physics Nuclear Experiment Instrumentation Helium Physics 010308 nuclear & particles physics Instrumentation and Detectors (physics.ins-det) chemistry Ultracold neutrons Neutron source Physics - Accelerator Physics Superfluid helium-4 Spallation Neutron Source |
| Popis: | We report on our efforts to optimize the geometry of neutron moderators and converters for the TRIUMF UltraCold Advanced Neutron (TUCAN) source using MCNP simulations. It will use an existing spallation neutron source driven by a 19.3 kW proton beam delivered by TRIUMF’s 520 MeV cyclotron. Spallation neutrons will be moderated in heavy water at room temperature and in liquid deuterium at 20 K, and then superthermally converted to ultracold neutrons in superfluid, isotopically purified 4 He. The helium will be cooled by a 3 He fridge through a 3 He– 4 He heat exchanger. The optimization took into account a range of engineering and safety requirements and guided the detailed design of the source. The predicted ultracold-neutron density delivered to a typical experiment is maximized for a production volume of 27 L, achieving a production rate of 1.4 ⋅ 107 s−1 to 1.6 ⋅ 107 s−1 with a heat load of 8.1 W. At that heat load, the fridge can cool the superfluid helium to 1.1 K, resulting in a storage lifetime for ultracold neutrons in the source of about 30 s. The most critical performance parameters are the choice of cold moderator and the volume, thickness, and material of the vessel containing the superfluid helium. The source is scheduled to be installed in 2021 and will enable the TUCAN collaboration to measure the electric dipole moment of the neutron with a sensitivity of 10−27 e cm. |
| Databáze: | OpenAIRE |
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