TY  - CONF
AU  - Barnsley, Lester
AU  - Feoktystov, Artem
AU  - Babcock, Earl
AU  - Salhi, Zahir
AU  - Frielinghaus, Henrich
TI  - Polarization analysis on the small-angle neutron scattering diffractometer KWS-1: A faster, more versatile instrument
M1  - FZJ-2019-05697
PY  - 2019
AB  - A number of upgrades have been made to the KWS-1 small-angle neutron scattering (SANS) instrument, operated by the Jülich Centre for Neutron Science (JCNS) and located at the research reactor FRM II of the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany. A neutron flux on the sample of 1×108 cm−2 s−1 makes it one of the most intense SANS instruments in the world, while an optional double-disc chopper can reduce wavelength spread down to Δλ/λ = 1% [1], allowing for high resolution measurements. In this presentation, we will describe two recent upgrades, aimed towards optimization of studies of nanoscale magnetic correlations.  The first is the installation of an upgraded detector. In September 2018, we were able to achieve commissioning of a new detector consisting of an array of 3He tubes interfaced with fast electronics (supplied by GE Reuter Stokes, OH, USA) to minimize dead-time for high-intensity measurements. An increase in the total detected area resulted in a new maximum Q-range of 0.7 Å−1, a 60% improvement over the previous geometry. 3He provides improved discrimination from background events, increasing signal-to-noise, while a faster detector response allows us to increase the source aperture for even shorter measurement times. In-line with our development of KWS-1, particularly for the magnetic SANS community, we report on recent developments for the option of measuring with polarization analysis. An analyser cell with polarized 3He allows detecting all four scattering cross-sections with a Qmax > 0.06 Å−1. The 3He cell is contained inside a μ-metal chamber, designed in-house by our JCNS 3He group, to ensure a high degree of uniformity of the magnetic field at the cell position. In recent experiments, a cell lifetime of more than 90 hours was achieved. The achieved cell lifetime is more than 90 hours. A new option for in-situ polarization of a 3He cell, allowing for time-independent analyzing efficiency of post-scattered neutrons, will be discussed.
T2  - 64th Annual Conference on Magnetism and Magnetic Materials
CY  - 4 Nov 2019 - 8 Nov 2019, Las Vegas (United States)
Y2  - 4 Nov 2019 - 8 Nov 2019
M2  - Las Vegas, United States
LB  - PUB:(DE-HGF)24
UR  - https://juser.fz-juelich.de/record/866616
ER  -