Beamline Equipment

The I16 Kappa-geometry 6 circle diffractometer

The I16 diffractometer is a 6-circle kappa geometry diffractometer, capable of aligning a sample in any orientation relative to the incident beam.

The large sample space provides space to fit a wide range of sample environments including cryostats, fields and various detectors.

We use a eulerian geometry to drive the sample and detector positions, however these are not always the true motors, for example Chi is a composite of real motors kappa and kphi.

In GDA it is possible to drive the diffractometer using standard Eulerian angles, with the naming convention shown below:

We typically operate the diffratometer in one of two geometries - Vertical or Horizontal, however alternative geometries are possible, for example grazing incidence.

We use DiffCalc to drive the diffractometer directly in reciprocal space, allowing a large number of movement modes including - fixed phi, bisecting, fixed alpha, fixed psi (azimuth).

Read more about the diffractometer: I16 6-axis Diffractometer

Technical Specifications 

The main mirrors on the beamline focus the beam to ~200(h) x 30(v) microns, however further focussing is possible using a set of fixed alignment Kirkpatrick-Baez (KB) mirrors on a motorised tripod system.

This system allows us to achieve microfocussing at the sample position of a few microns.

Setting up the KB mirrors and aligning them is a time consuming process and must be requested prior to beam time.

The Pilatus3 100K is our workhorse detector used for the majority of measurements. The detector is in-vacuum and has an ultra-high gain option for low energy measurements. The detector is mounted on the detector arm ~8 degrees above the analyser crystal, alowing us to easily switch between different detectors.

Pilatus Geometry

Quad Merlin detector inside PA vessel on I16. The detector is 1,310 mm from the sample and 60 mm from the analyser crystal.

Merlin Geometry

This large area detector sits on an extending table to control the detector distance. Horizontal and vertical alignment is possible on the table, and the table can be manually rotated around the gamma-axis of the diffractometer.

Additional options for the Pilatus 2M include a flight tube and beam stop.

Pilatus 2M Geometry

Detector image

Flight Tube

Illustration and inset-example of sample mounted with electric contacts in scattering geometry

Power supplies available

• Keithley 1100V source-meter (model 2410)
• Trek 10 kV amplifier (model 610A)
• Agilent waveform generator (model 33220A)

Specifications: Keithley 2410 1100V Source meter

Specifications: Agilent 33220A Arbitary waveform generator

Electromagnets

• Rotating magnet
• 1T water-cooled electromagnet
•  

Permenent Magnets

A sample mounted on the Razorbill CS100 insitu strain cell, mounted on the cryostat on I16.

Using a Razorbill CS100 strain cell, we have the ability on I16 to measure x-ray diffraction, including resonant and magnetic scattering, from samples while applying tensile and compressive uniaxial strain, even at cryogenic temperatures. The high angular resolution of I16 provides accurate determination of the strain based on diffraction measurements. In particular it is possible to use reciprocal space mapping to watch the change in Bragg peak shape under strain. A full range of resonant measurements is possible, including polarisation control and analysis, energy scanning and azimuthal scans. Sample are typically mounted in reflection geometry on the strain cell and adhered using Stycast or another hard epoxy resin.

The specifications for this device are given in the table below:

On I16, the strain cell is mounted on the ARS cryocooler, providing cooling to <10K. The cold head operates in-vacuum with a Beryllium dome for x-ray transmission in reflection geometry. This geometry provides maximum access for the incident and scattered x-ray beam in a range of scattering geometries. The cell’s power supply and measurement of the cell capacitance (to determine relative displacement) have been implemented into the beamline software allowing full strain/ temperature phase maps to be automated.