kws-3

KWS-3 'VerySANS'

unofficial page of focusing VSANS diffractometer operated by JCNS@MLZ

KWS-3 is a very small angle neutron scattering (VSANS) diffractometer operated by JCNS at Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany.
KWS-3 is historical official name of the instrument. JCNS at MLZ is operating two more KWS-x instruments: two classical pinhole SANS diffractometers KWS-1 and KWS-2. To show that KWS-3 differs from pinhole SANS instruments, KWS-3 obtained the second name 'VerySANS'.
The principle of this instrument is one-to-one imaging of an entrance aperture onto a 2D position sensitive detector by neutron reflection from a double-focusing toroidal mirror.
In current state [2021], KWS-3 is covering Q-range between 3·10^-5 and 3·10^-1 Å^-1 and used for the analysis of structures between 20 Å and 20 μm for numerous materials from physics, chemistry, materials science and life science, such as alloys, diluted chemical solutions, hydrogels and membrane systems.
Within the last few years we have finalized several big “evolutionary” projects; we have completely re-designed and commissioned the main components of the instrument: selector area, mirror positioning system, main sample station at 10m, beam-stop system; implemented new sample stations at 3.5 and 1.3m, second (very-high resolution) detector, polarization and polarization analysis systems; adapted the instrument to almost any existing/requested sample environment like 6-position Peltier furnace (-25°C to 140°C), high-temperature furnace (< 1600°C), cryostats/inserts (>20 mK), liquid pressure cell (<5 kBar/10-80°C), CO₂/CD₄ gas pressure cell (<0.5 kBar/10-80°C), humidity cell/generator (5-95%/10-90°C), magnets (horizontal < 3T, vertical < 2.2T), Bio-logic® multimixer stopped flow (5-80°C), rheometer RSA II (tangential/radial) etc.

Focusing Element:

Toroidal Mirror

Geometry of the instrument is defined by geometry of the mirror
Shape: Toroidal ≈ Ellipsoidal
Size: 120x12x8cm³ (2x 60x12x8cm³)
Toroid: Radius_Meridional=531m; Radius_Sagittal=0.224m
Focus-to-Focus Distance: 22m
Ellipse semi-axises: 11.230m and 0.224m
Coating ⁶⁵Cu: m=1, λ=12.8Å ⇒ θ_c=0.1·m·λ=1.28°
λ=12.8Å: θ=[1.16°… 1.23°]

Highest Resolution

(V)SANS instrument

High Brilliance Neutron Source
2D Focusing Toroidal Mirror
Non-magnetic coating ⁶⁵Cu
Ångstrom roughness ⇒⇓
Signal-to-noise ratio: better 10⁵
Geometrical focusing, λ independent
~ 100% reflectivity above 12Å [10Å:<10% and 8Å: <1%]
Q-range: 3·10^-5 … 3·10^-1 Å^-1
Best resolution: 3·10^-5Å^-1 ⇒ 20μm
Lowest resolution: 3·10^-1Å^-1 ⇒ 20Å
Broad Dynamical Range: Q_max/Q_min=10⁴

Mirror & detector are movable

Modes: (V)SANS, GiSANS, Reflectometry

Flux vs. Sample-to-detector distance

Flux at the detector: ≈ 6000 n/sec/mm² [12.8Å]
Flux at the sample: ∼D²
Maximal beam size at the sample is defined by the mirror geometry

≈ 80x20mm² at SDD≈10m

≈ 35x10mm² at SDD≈4m

≈ 10x 5mm² at SDD≈1.6m

Status 2020

Sample-to-detector distance: 10m, 9.5m, 1.3m (User Mode) and 0.03 to 0.45m (Test Mode)
Wide Q-range: 4·10⁻⁵ < Q <2.5·10⁻² Å⁻¹ (9.5m & 1.3m, λ=12.8Å, VHRD & HRD)
Qmin =2·10⁻⁵ Å⁻¹ (#0 SD=10m, λ=30Å)
Qmax = 0.45 Å⁻¹ (#4 SD=0.05m, λ=12.8Å)

KWS-3 'VerySANS'

Focusing Element:

Highest Resolution

Mirror & detector are movable

Flux vs. Sample-to-detector distance

Status 2020

Status 2022: multi sample position approach

Q-range: compact sample environment

Q-range: bulky sample environment