VERITAS: a high-flux neutron reflectometer with vertical sample geometry for a long pulse spallation source

International Conference on Polarised Neutrons for Condensed Matter Investigations 2014

Mattauch, S.^1 ; Ioffe, A.^1 ; Lott, D.^2 ; Menelle, A.^3 ; Ott, F.^3 ; Medic, Z.^4

JCNS at MLZ, Forschungszentrum-Jülich GmbH, Garching

85747, Germany^1

Helmholtz Zentrum Geesthacht, Geesthacht

21502, Germany^2

Laboratoire Léon Brillouin CEA/CNRS, CEA Saclay, Gif sur Yvette

91191, France^3

Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovia 3, Novi Sad

21000, Serbia^4

关键词: High flux neutrons;    Magnetic correlation;    Neutron reflectivity;    Off-specular scattering;    Orders of magnitude;    Polarisation analysis;    Reflectivity measurements;    Spallation sources;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/711/1/012009/pdf
DOI  :  10.1088/1742-6596/711/1/012009

来源: IOP

【 摘 要 】

An instrument concept of a reflectometer with a vertical sample geometry fitted to the long pulse structure of a spallation source, called "VERITAS" at the ESS, is presented. It focuses on designing a reflectometer with high intensity at the lowest possible background following the users' demand to investigate thin layers or interfacial areas in the sub-nanometer length scale. The high intensity approach of the vertical reflectometer fits very well to the long pulse structure of the ESS. Its main goal is to deliver as much usable intensity as possible at the sample position and be able to access a reflectivity range of 8 orders of magnitude and more. The concept assures that the reflectivity measurements can be performed in its best way to maximize the flux delivered to the sample. The reflectometer is optimized for studies of (magnetic) layers having thicknesses down to 5Å and a surface area of 1x1cm2. With reflectivity measurements the depth-resolved, laterally averaged chemical and magnetic profile can be investigated. By using polarised neutrons, additional vector information on the in-plane magnetic correlations (off-specular scattering at the pm length scale, GISANS at the nm length scale) can be studied. The full polarisation analysis could be used for soft matter samples to correct for incoherent scattering which is presently limiting neutron reflectivity studies to a reflectivity range on the order of 10-6.