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X-Ray Crystallography

The aim of this project is to use a narrow beam of X-Rays to produce an image/data that reflects the atomic and molecular structure of atoms in a crystal. The method used is called X-Ray crystallography where a narrow beam of X-rays is fired at a crystal, although most will pass straight through some of the x-rays are diffract by the lattice of atoms arranged in a crystal which sum and subtract to create an interference patterns at an angle to the main beam.

Braggs Law

Crystals are regular arrays of atoms, and X-rays can be considered waves of electromagnetic radiation.  Atoms scatter X-ray waves, primarily through the atoms' electrons. Just as an ocean wave striking a lighthouse produces secondary circular waves emanating from the lighthouse, so an X-ray striking an electron produces secondary spherical waves emanating from the electron. This phenomenon is known as elastic scattering, and the electron (or lighthouse) is known as the scatterer. A regular array of scatterers produces a regular array of spherical waves. Although these waves cancel one another out in most directions through destructive interference, they add constructively in a few specific directions, determined by Bragg 's law:  2d \sin \theta = n \lambda

I bought an X-ray tube for this project, to provide a narrow beam of x-rays. It's called a diffraction transmitting target x-ray tube made in Soviet Russian times during the 1990s type BS7-W. As it turned out the design of this tube is quite unusual, but nevertheless it works quite well and produces a fine beam of soft x-rays and a little more safer than other tubes to work with.  

More details about this here:   X-ray tube - diffraction transmitting target (Russian BS7-W)

As the tube requires a modest operating voltage of 15Kv and current for the Anode and a small voltage of 1.5V for the filament the power supply t was relatively easy to construct using commonly available components. 

Dual Power Supply


Here is the first test of the tube in operation. The Geiger Counter is first checked against other radioactive sources to gauge roughly relative output levels. 



Power Supply and X ray Tube