## Description of the system

The system to be studied in this project is the container of the instrument D4 together with the elements it contains. In particular, the sample, located in the central point of the container, is an element of special interest. The picture shows the diagram of the diffractometer D4.The system corresponds to the blue cylinder in the center of which the sample is placed. In red you can see the path followed by the neutron beam from the point it enters the system until it collides with one of the detectors that make up the detector bank behind the container.

## Main Components

### Container

It is a cylindrical chamber with a radius of 250 mm mainly made of stainless steel and some elements of aluminum.The container has an upper lid allowing access to the interior for placing or removing components.

The enclosure is totally watertight and by means of a pumping system a pressure below $10^{-3}$ mbar is reached. Thus, it is considered that experiments are carried out in vaccum conditions.

### Heating system

The heating system is the element that brings thermal energy to the system by radiation. It is made up mainly of two elements: the heating cylinder and the thermal shields.

• The heating cylinder is the resistive element of an electric circuit. It is heated up by Joule effect due to the electric current that flows through the circuit and transfers thermal energy to the sample. This component is made of a thin sheet of vanadium, with a thickness of 0.1 mm, rolled up so as to have a cylindrical shape.
• The shields are cylindrical elements made of stainless steel that are placed in the upper and lower areas of the heating cylinder. Their main aim is to reduce heat losses between the cylinder and the outside, keeping, this way, the temperature of the sample as high as possible.

### Support of the sample

It is an element designed to hold and place the sample at the proper height within the instrument D4. It is made up of three elements, mentioned from top to bottom:

• Support of the sample made of boron nitride. Component adapted to the sample’s dimensions so that it can be placed on it.
• Alumina tube with the appropriate measurements to place the sample in the central region of the heating cylinder. Alumina is a material with a good temperature resistance.
• Stainless steel base that joins the support of the sample with the lower part of the container.

### Sample

The sample is the main element of this study. Its dimensions are 70 mm in lenght by 10 mm in diameter.