Big Cherenkov Simulator

September 29, 2016

Idea

This project simulates the blue glow seen in water around reactors and highly radioactive materials, but without the dangerously high levels of radiation. Instead a UV lamp is used as a light source, and a blue dye in the water causes a similar volumetric glow effect. I already tested out the concept a few years back with a small water bottle, and at this point I wanted to have a more permanent fixture.

Supplies

  1. Acrylic tube - 6 inch ID, 1/4in thickness, 2ft length
  2. 4 Acrylic plates 7x7x.375 inches
  3. UV lamp to match length of the above tube
  4. O-rings to match the diameter of UV lamp (optional)
  5. Power supply for UV lamp (using an HV supply instead of the standard ballast allows for operation with only 2 wires instead of 4)
  6. Water-tight (silicone/"aquarium") sealant - I used the DAP "All-Purpose Adhesive Sealant 100% Silicone", haven't had any leaks yet
  7. "Invisible blue" UV dye - available online, such as uvgear.co.uk
  8. Rope to secure the structure


A UV lamp, sealant, acrylic tube, and rope.

Construction

First I milled grooves in the acrylic plates to match the tube and also the UV lamp, so that both can be sealed in a water-tight fashion. To avoid stresses on the glued joints when moving the light, there are four holes through which a rope is passed, that puts tension on the structure and makes it more rigid.


The four acrylic plates after machining, before and after removing the protective paper cover. The top two attach to the tube to make it water-tight, and the bottom two keep the wires in place.

The silicone sealant requires ventilation to cure, so the pieces are glued incrementally with about 24 hours curing time in between. I began with the UV lamp, which I temporarily suspended with a string since there was no top support.


The UV lamp is glued to the bottom plate.

Next the tube is glued to the bottom plate. To ensure the sealant fills the entire joint thoroughly I placed some weight on the structure.


An old PC and a wire spool add weight to the structure while the adhesive dries.

At this point the tube can be filled up with water and the UV lamp/dye tested to see that there are no leaks and that the effect is as desired.


First test with water in the structure, and trying different dye concentrations.

Then the rest of the structure is filled up (with a way to circulate air so the sealant cures) and ropes used to secure the top and bottom plates.

Results

It turned out to be a nice nightlight, with the desired 'Cherenkov' simulation, but the UV lamp I had available is only 15W which means this is difficult to see even with typical room lighting, much less in daylight. It would be easier to see against a black background. The addition of a UV filter on the outside of the tube will make the effect more authentic, since at present some UV light still passes through and breaks the illusion that the water is glowing on its own.


How the light looks when turned off, and when turned on.