Low dimensional cold moderator systems

Topic  2
Main supervisor U.Rücker (u.ruecker@fz-juelich.de)
MLZ institution FZJ
Local supervisor 1 Tamasz Grozs
Institution HNF Technologies
Local supervisor 2
Local supervisor 3
Local supervisor 4
Title Low dimensional cold moderator systems
Description Moderation of neutrons towards the energies of some meV is required to achieve the spectrum demanded by neutron instruments. For neutron energies in the range of 1 to 10 meV moderator materials at cryogenic temperatures are applied e.g. liquid hydrogen H2, solid methane CH4 or solid mesitylene C9H12. To improve the brilliance of such moderator systems low dimensional moderator systems have been developed in recent years. A special system of a one-dimensional cold moderator device has been developed with the HBS project at JCNS. This system allows to equip an individual neutron instruments with its own dedicated cold source as part of the neutron guide system of the instrument. For an optimal setup of such an individual cold moderator system, corresponding simulations of the nucleonic performance of the moderator geometry, spectrum and brilliance is required, as well as the cryogenic engineering and implementation of the device in the instrument guide system. In collaboration with HFN Technologies options for the development and implementation of such cold moderator system will be investigated for application at existing instrument at neutron facilities as MLZ. Special emphasis will be given for the implementation within the setup of accelerator-based neutron sources as with the HBS project under developed at JCNS. Work to be done for the development of one-dimensional cold moderator systems will cover: – nucleonic simulations on the performance of moderator geometries with MCNP or FLUKA; – ANSYS simulation of the mechanical and cryogenic performance of the moderator; – construction and testing of the moderator system. The realization of this project will provide a route to upgrade existing instruments at neutron facilities as MLZ for cold neutron applications and deliver critical components in the frame work of upcoming accelerator-based neutron sources as HBS.