MoTo
MoTo (Monochromatic Tomography) is an instrument that provides monochromatic and advanced imaging modes in a branch of NeXT. A monochromator using a single reflection via a highly oriented pyrolytic graphite (HOPG) crystal provides a beam at a fixed take-off angle with a wavelength of 2.4 Å. MoTo was designed for long experiments with advanced contrast options to measure independently of NeXT. Access to the hutch is possible only when the NeXT beam is off, and needs to be coordinated with the users and local contacts of NeXT.
MoTo and NeXT are located at the end of the H521 guide shared with D16 and SuperADAM.
Applications
- 2D and 3D monochromatic neutron imaging with a field of view of up to 60x60 mm2 and typical pixel sizes of approx. 50 µm.
- Quantitative determination of the linear attenuation coefficient at the fixed wavelength of 2.4 Å.
- Neutron grating interferometry in Talbot-Lau geometry (max. correlation length currently 5.6 µm).
- Polarised neutron imaging using solid-state benders as polariser, and analyser. A guide field allows placing the polariser at about 2 m from the sample position.
Instrument layout
MoTo gets its beam from a pinhole at the end of the guide that is located above the ones providing neutrons to NeXT. After the HOPG crystal (0.8 degrees mosaicity), there is a second aperture that can be closed step-less to reduce the collimation ratio. Flight tubes minimise air activation and scattering.
The sample is placed on a rotation stage (allowing images under different projection angles to be acquired) approx. 4.5 m from this second aperture and can be translated along the beam direction (travel approx 500 mm) with respect to the - also movable - neutron detector.
The indirect detector acquires transmission neutron radiographs and is composed of a scintillator, an optical lens system and a CMOS camera.