TY - BOOK

T1 - Exploration of the Challenges of Neutron Optics and Instrumentation at Long Pulsed Spallation Sources

AU - Klenø, Kaspar Hewitt

PY - 2013

Y1 - 2013

N2 - In this thesis I have explored the challenges of long guides and instrumentation for the long pulsed European Spallation Source. I have derived the theory needed for quantifying the performance of a guide using brilliance transfer. With this tool it is easier to objectively compare how well different guides perform the same task.In comparing different guide geometries, I have shown that for transporting thermal orhighly divergent neutrons over medium to long distances, elliptic and parabolic guides are significantly better in terms of brilliance transfer than simpler guides. I have also shown that the transport of a neutron beam over a very long distance is quite feasible,even for highly divergent, thermal neutrons.I have investigated various methods for blocking the direct line of sight between theneutron source and the sample area, in order to reduce the fast neutron background.I have shown that doing this is feasible, even for advanced guide geometries, such as elliptic and parabolic guides. I have also looked into how guide imperfections affect the brilliance transfer, and shown that long elliptic guide are robust against imperfections at the levels we expect to see.I have also detailed the simulations and optimisations of one particular instrument,the Compact SANS, on which I have worked on the design of the guide, collimation,and chopper systems.

AB - In this thesis I have explored the challenges of long guides and instrumentation for the long pulsed European Spallation Source. I have derived the theory needed for quantifying the performance of a guide using brilliance transfer. With this tool it is easier to objectively compare how well different guides perform the same task.In comparing different guide geometries, I have shown that for transporting thermal orhighly divergent neutrons over medium to long distances, elliptic and parabolic guides are significantly better in terms of brilliance transfer than simpler guides. I have also shown that the transport of a neutron beam over a very long distance is quite feasible,even for highly divergent, thermal neutrons.I have investigated various methods for blocking the direct line of sight between theneutron source and the sample area, in order to reduce the fast neutron background.I have shown that doing this is feasible, even for advanced guide geometries, such as elliptic and parabolic guides. I have also looked into how guide imperfections affect the brilliance transfer, and shown that long elliptic guide are robust against imperfections at the levels we expect to see.I have also detailed the simulations and optimisations of one particular instrument,the Compact SANS, on which I have worked on the design of the guide, collimation,and chopper systems.

UR - https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122702572005763

M3 - Ph.D. thesis

BT - Exploration of the Challenges of Neutron Optics and Instrumentation at Long Pulsed Spallation Sources

PB - The Niels Bohr Institute, Faculty of Science, University of Copenhagen

ER -