The cryostat on D2am Material sciences goniometer

Description of the cryostat.

A cryostat can be set inside the phi circle of the goniometer. This is a small 2 stages displex from cryosphysics. Two Be hemispheres allow the diffraction. The inner sphere ( 50mm diameter )can be filled with an exchange gas to improve the temperature conduction between the cold exchanger and the sample.

 

Sample holder.

The sample is hold by a small goniometer head (0.12.1 from STOE), which main characteristics are : tranlational movement:+-1.5mm, adjustement of arcs +-25.

The center of the head is 6.5 mm above the top of the head which contains a small hole for M2 screw (2mm deepth). A ring with a smaller hole cat be put in this hole.

It is suggested that users put a marker with heavy absorption at a known position (typically one mm below the sample) to help centering of the sample in the beam at low temperature when the Be sphere are used.

Temperature regulation.

It run with a autotuning temperature controller model 330 from LakeShore. There are two thermometers channels, one is dedicated to the temperature control, it uses a Silicon Diode, the other thermometer is near the sample and is a Silicon or a Platinium resistor. The main user functions are: