The Mad Scientists of Etsy Challenge for January 2011 is 'Particle Physics' so I listed another of the screenprints I made last spring: Cloud Chamber II.
This is a two colour screenprint I made of clouds and ionization tracks in a cloud chamber.
A Wilson cloud chamber is basically a tank of condensed, supercooled water (or alcohol) vapour. It is used to detect high energy particles - ionizing radiation. The radiation, say from cosmic rays, or radioactivity, or particle accelerators and so forth, leave their distinctive trails in the "clouds". Because of conservation laws (conservation of angular momentum, and conservation of charge, in particular) you get these wonderful spiralling trails. If you look carefully, there's a whole lot of symmetries in the image. In fact, if you look really carefully and measure angles, it's possible to get the mass to charge ratio of the particle in question. It's really a magic piece of 20th century science instrumentation.
I printed the sky in pale blue, using a digitally manipulated photograph of the sky, and the ionization trails in sunny yellow. This is an artist's proof.