LADI-III

Quasi-Laue diffractometer

Guide hall n°1, cold guide H143

Data Collection Method
Quasi-Laue	Ni/Ti multilayer band-pass filter (δλ/λ=30%)
Typical neutron λ range	~2.8 to 3.8 Å

Collimation
Pinholes	0.5 to 2.9 mm

Flux at specimen
(λ-centre = 3.3 Å; δλ/λ = 30%)	~1.1 x 10⁸ n cm^-2 s^-1

Detector
Cylindrical drum with internal neutron-sensitive image plates and read/erase system
Neutron image plate	Gd₂O₃ doped BaF(Br.I):Eu²⁺
Radius	200 mm
Length	450 mm
Active area	1250 x 450 mm²
Angle subtended	172° in θ, 49° in ν
Pixel size	125, 250, 500 µm²

Sample environment
(1) Ambient or (2) Oxford Cryosystems 'COBRA' cryostream (down to 80K)

Upgrades allow smaller crystals and more challenging studies

Due to the low flux of even the most intense neutron sources, neutron macromolecular crystallography has historically been an intensity limited technique, requiring very large crystal volumes and long acquisition times. However, over the years, LADI-III has gone through a number of upgrades, such as its relocation in 2010 to the end-position of a new guide (H143), and these have dramatically reduced both the crystal volumes required and the data collection times. This has placed LADI-III's performance in a world-leading position, despite the more recent appearance of instruments at other neutron facilities, such as BioDiff at FRM-II, MaNDi at SNS and iBIX at J-Parc. The smallest crystals used, largest systems studied and fastest data collections have all been achieved using LADI-III. Currently, LADI-III utilizes a multilayer bandpass filter for wavelength selection. The replacement of the multilayer bandpass filter with a neutron velocity selector is a planned upgrade in 2026 that will increase the neutron transmission by a factor of ~2.

This upgrade will allow further reductions in the crystal volumes required or data collection times. In addition, it will provide more flexibility in terms of wavelength bandwidth choice so as to further optimize data collection strategies.