ATHOS

ATHOS instrument is a multipurpose instrument. It’s main use is the investigation of mechanical strain in structural materials, but also used as a neutron optical test station to test neutron detectors, monochromators etc. The accessible wavelength is between 2 and 5.5 Å. The sample positioning system consist of an X-Y table and a rotating table giving possibility of moving the sample 10 cm in two direction and rotating around the vertical axis. The size of the measured volume is defined by slits before and after the sample. The maximal viewing angle of the detector is 6o.
The samples are mostly made of steel or aluminium alloy, but thanks to the large wavelength range, samples consist of a variety of crystalline materials can be investigated.
For neutron-optical test measurement Ge(111) crystal can be used as a higher order filter giving a clean beam between 2 and 4 Å.

ATHOS instrument is located at the 1st cold beamline 17m far from the cold source. The monochromator is vertically focusing pyrolithic graphite with the mosaicity of 0.40. The take-off angle can be varied between 360 and 1100 giving the wavelength range of 2-5.5 Å. For strain measurement the (004) reflection of the monochromator is used . The scattered neutrons are collected with a 3He filled 2D position sensitive detector with the spatial resolution of 1.5mm. The sample positioning system consists of an omega-table and XY table. The initial sample position and orientation is set using laser and theodolite. The strain scanning measurement follows the VAMAS procedure.
The instrument is also used as a neutron optical test instrument. Detector efficiency, homogeneity and resolution, monochromators and other reflective neutron optical devices can be tested. The Ge(111) analyser allows to get clean beam without higher order contamination. The background with open beam without sample is less than 1cnt / minutes.

ATHOS characteristics (default configuration)		Details
Beam	Cold neutron guide No. 10/1	Cross section of the neutron guide at the exit: 100 x 25 mm2
Detector	2D position sensitive	Type: 3He-CF4 gas detector Size: 200×200 mm2 Resolution: 1.5 mm
Monochromation	pyrolithic graphite monochromator	. Vertically focusing, mosaicity is 0.4o
Wavelength range	2 – 5.5 Å	Using PG(002), PG(004) reflection. Relative wavelength resolution: 0.4% – 2% depending on take-off angle
Collimation length	2.2 m	Optionally 1.5 m
Beam definition system	x-y slits before and after the sample	Manually adjustable
Gauge volume size	2-5 mm	Adjustable independently in 3 directions
Scattering angle range	-80o – 107o	Using 1.5m primary collimation: -80o – 80o
Sample to detector distance	0.9 to 1.5 m
Scattering vector range	0,.5 – 5 Å-1	Relative resolution 0.8% for Fe(110) at 2θ = 90o
Sample position system	Rotation + 2D movement	Rotation around vertical axis with 0.02o resolution, X-Y or X-Z movement with 0.1 mm resolution
Optional analyser	Pyrolithic graphite /Ge(111)_	tGe(111) can be used as higher order filter