ZEBRA: Thermal Single Crystal Diffractometer

The thermal neutron single crystal instrument ZEBRA is a flexible monochromatic diffraction instrument for applications in magnetism and classical crystallography, covering fields such as materials science, multiferroics, highly correlated electron systems. The available neutron wavelengths (1.18Å, 1.383Å and 2.31Å), the flexible computer controlled inpile-collimation, the three detectors (single tube, single tube with analyser, 160mm x 160mm area detector with radial collimator) and the possibility to tilt detectors out-of-plane are key components.

Operating in 4-circle mode (1.5K up 1200K) or tilting mode (50 mK up to 1200 K, fields horizontal up to 4.5 Tesla, vertical up to 12 Tesla, pressures up to 100 kbar) gives access to a wide range of conditions. Special sample environment brought-in by the user can also be easily installed.

Complicated modulated structures can be investigated by the possibility to switch from the single detector to the area detector by one turn. Dedicated software allows analyzing area detector data and complete datasets in a fast way, making them ready in formats commonly used refinement programs.

Details of the instrument can be found in the description section, in particular the instrumental parameters and the available dedicated sample environment for the 4-circle mode.

ZEBRA is operated by the Laboratory for Neutron Scattering and Imaging, LNS.

Beam Tube	SINQ, thermal beam tube R42, H₂O-scatterer
Monochromators	Ge₃₁₁ (λ = 1.177 Å), Ge₂₂₀ (λ = 1.383 Å) and PG₀₀₂ (λ = 2.317 Å), vertical focusing 2Θ_{Monochromator} = 38.8^o (fixed)
Optional Collimation	80', 40', 20'
Resolution	Δd/d > .005
Flux at Sample	max. 2.2x10⁶ n/cm²/sec (1.35mA on SINQ)
Crystal Size	ideal 3-5 mm³, down to sub 0.1 mm³ and not larger than 1cm² cross section (size of homogeneous beam)
xyz-Adjustment	x,y:+/- 15mm, z:+/- 30mm

Secondary Instrument (I)
- 2D He³-area-detector, 160 mm x 160 mm (oscillating radial collimator)
- single He³-tube (soller collimator: 80', 40', 20')

Secondary Instrument (II)
- single He³-tube (soller collimator: 80', 40', 20') with PG analyser

Momentum transfer
6^o< 2Θ <128^o, λ=1.18Å: max.sinΘ/λ=0.77 Å^-1, λ=2.317 Å: max.sinΘ/λ=0.39 Å^-1

Operation modes

ZEBRA is operated in two operation modes: 4-circle equatorial geometry (γ = 0^o) and tilting geometry(-14.5^o< γ <15^o)

Equipment for 4-circle-mode

cryogenics 15-450 K (APD), 4.5-300K (CCR3)
cryogenics (1.7-300 K, JT-CCR)
pressure cell (20 kbar, T > 4.5 K)
photocrystallography (400-800 nm, 100mW/cm², T > 50 K)
vacuum furnace (300K-800K)

Equipment in tilting mode

magnetic field: 6 and 10 Tesla vertical magnets with large out-of-plane openings, 12 Tesla vertical in MA15 (small vertical opening), and 4.5 Tesla horizontal in MA7
cryogenics (T > 50 mK (dilution stick))
furnaces (<2000K)
any other equipment available at PSI