Source of Idea:
In the lobby of the visitor's center at the European Laboratory for Particle Physics (CERN, where the World Wide Web was invented!) in Geneva, Switzerland, is a "sculpture" that sits flush with the floor that consists of swirling flat metal shapes with frosted plexiglass between. Seemingly random coloured lights flash underneath. Upon reading the accompanying brass plaque, the sculpture was designed by Serge Moro in collaboration with the CERN workshops in 1987. The flashing of the lights are controlled by the passage of cosmic ray particles through the floor itself, passing through slabs of scintillator below the floor to trigger a flash of light in the panel where the cosmic ray passed through. What initially appears to be a pleasing floor design with coloured lights turns out to be a fascinating display of the constant rain of cosmic rays from outer space passing right through visitors and the floor as they stand on the sculpture itself.
Adaptation:
The original consisted of hexagonal panels, rounded at the edges to make a circle embedded in the floor. This would take a large amount of machining and work to get just right. Instead, 16 square panels are proposed. Beneath each panel are lamps (could be coloured) that are triggered by a cosmic ray particle passing through two slabs of scintillator plastic (special plastic that gives a tiny flash of light when a subatomic particle passes through it).
The tiny flash of light in each slab would be detected by either sensitive semiconductor light detectors (low voltage, would probably have to buy) or photomultiplier tubes (can probably obtain donations of old, but useable, ones from the IU Physics Department (need high voltage, high voltage power supplies, meeting electrical code?) When a flash is seen in each slab in coincidence, control electronics would then trigger the lamps beneath that particular to flash, with a time duration that can be controlled. Cosmic ray particles come at an average of approximately 1 per square cm per min. and this rate can be changed by adjusting the trigger threshold.
Such an exhibit can be embedded in the floor near either ground floor entry and would have an impact on visitors walking in. Upon reading the posted explanations, they will realize that if a panel beneath them has flashed, then a cosmic ray has probably passed right through their body and through the floor to trigger the lamps below. Sources of cosmic rays, how they are "normal" and will not hurt you, particle physics, etc. can be explained in simple terms.
A sketch of the layout is below (with a link to a postscript of the same figure). I shudder to give dimensions in inches and feet instead of metric, but this is for the architects.
Postscript file of the above drawing. Much better resolution.
The whole 8 foot square exhibit could be laid out in a diamond fashion (greater interest?) or square on for people entering the building. It could be immediately following the south entry doors, a bit further on so that it is centered on the area "open to above", so that people on the second floor can also see it from above, or immediately following the north entry doors. I will try to include a scan of the floor plan with a scale representation of the above "square" superimposed to give the idea.
Implementation:
Wherever it would be laid out, a "pit" or space approximately 12" deep and slightly more than 8' square would have to be provided below the existing floor level. A steel structure would be laid out that the panels can sit upon (picture the panels used for computing center or experimental electronics shack floors? Removable panels, space underneath). The panels would be 1" thick plexiglass (or whatever thickness needed to be fully load bearing for x number of people - a job for the architects to make sure to proper building code standards.)
The panels can be clear plexiglass, with a frosted or translucent finish on top so that people cannot see all the equipment below (or should they? Maybe leave one clear to show them how it works?) The exhibit at CERN has beautiful, arty swirls of flat metal of contrasting colours (aluminum and brass) with liquid plexiglass cast on all sides to make the whole thing flush and flat to the floor. A lot of work but very striking. A graphic theme that fits in well with the rest of the Wonderlab building could be appropriate as long as there was enough "open area" between to see the light flashes.
The panels can be secured down with bolts, countersunk heads, hex-keyed, countersunk appropriately so they are flush with the surface. This would allow access to the lamps and control circuitry beneath.
Estimated four 100W lamps per "panel", needing 6400 W for the lighting alone. May need additional hatch or space for control electronics, or integrated in the spaces between, and power needs for these. Consumption for low-voltage photodetectors not too serious. The total electrical needs could be provided by an estimated six 15-amp circuit provided in the sides of the shallow "pit" or spread across the bottom of the pit.
The scintillator can either be scrounged from the IU Physics Department, or I am even trying for a donation of spare "scintillating tiles" from the OPAL experiment.
Triggering, timing, and control circuitry can be "home made" in the Physics Department. Could make an ideal project for undergrads, Physics Club, etc.
Proposed Location:
Proposal A: Can be seen from above (second level) too. South entry traffic sure to see it. Is entrance to gift shop off of it too (can't tell)?
Proposal B:
Proposal C: Both north and south entry traffic will pass by (or on top of) the exhibit
You can e-mail me at Rick.Van.Kooten@cern.ch
This page last updated on January 30, 1998.
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