Glass Cloud Chamber example essay topic

I use a one-liter plastic canteen with flat sides and a wide mouth. The cap, being slightly tapered, fits snugly inside a tall drinking glass. If you find that the cap rests so deeply inside your glass that the canteen cannot be attached, ask the folks at a local glass shop to cut off some of the rim. You might also ask them to bore an off-center hole in the base of the glass for a stopcock-or do it yourself. Apply a gentle but steady pressure. It's best to use a drill press, but the job can be done with a handheld electric drill.

Wear suitable eye protection (as always, when working with power tools) and gloves, in the event the glass should shatter. Though unlikely, it's conceivable that your glass could break when it is pressurized. So you should also wear your safety glasses when experimenting. And you can add a further level of protection by coating the glass with plastic.

When your protective coating has fully dried, pass the threaded brass fitting through the hole, seal it carefully with silicone aquarium cement, secure it with a washer and nut, and add the stopcock. Also, find a supply of small ceramic magnets and glue one inside the glass at the top center using silicone cement. Next obtain a short length of PVC pipe with an outer diameter that is just slightly smaller than the mouth of the canteen. Cut a hole in the cap to accommodate the pipe, which should reach down to about two centimeters above the bottom. Glue the top end into the hole in the cap. Then stretch some plastic window screening across the top of the pipe.

The mesh reduces turbulence in the fluid, thereby reducing turbulence in the air inside the chamber. Secure the screening with a nylon cable tie. Then punch a small hole in the center of the screen. (You " ll need this opening for access to the chamber.) Finally, glue the cap into the glass using plenty of silicone cement and attach the lower stopcock just as you did the upper one. Now wrap two strips of adhesive tape most of the way around the drinking glass, positioned a few centimeters from the base. Run a third strip vertically along one side.

Then spray-paint the glass a flat black to improve contrast and make the particle tracks easier to see. You can now create viewing ports by removing the tape. To monitor the changing fluid level, make a photocopy of a ruler and glue your paper scale beside the vertical window. Adding baking soda to the liquid while everything is sealed up is simpler than you might think. Just epoxy a ceramic magnet into a small bag fashioned from the toe of a nylon stocking. I suggest you begin by adding 2.5 milliliters (about half a teaspoon) of baking soda to the bag, but you " ll probably need to adjust that amount after some trial and error.

Place the baking soda on a small piece of paper towel and insert this makeshift holder into the bag. Affix the bag just below the neck of the bottle using a stack of two magnets on the outside; removing the outer magnets releases the baking soda into the solution. I put a many as five bags inside at once so that I can repeat the experiment without opening the canteen. Mix two liters of liquid by combining equal parts of distilled vinegar and the most concentrated isopropyl alcohol you can find.

Squirt in some ink, which (like the black spray paint) will make the tracks easier to see, and add two milliliters of salt. Fill the generator bottle with this solution to within about one centimeter of the nylon bags. Open the top stopcock and then screw the glass cloud chamber on tightly. You may need to cover the threads with Teflon tape or petroleum jelly to get a pressure-tight seal. Insert the whole assembly in its holder. Now open both stopcocks, carefully suck on the tube until liquid fills the cloud chamber about halfway, then close both stopcocks.

Position a bright light to one side of your viewing port. Drop in a bag of baking soda and monitor the fluid level in the cloud chamber. Particle tracks can appear only during the next brief instant, so the odds of seeing a vagabond cosmic ray are not at all good. A potent source of either alpha particles (helium nuclei) or beta particles (electrons) provides a much more satisfying show.

Alpha particles produce short tracks, whereas beta particles leave long ones. Epoxy your radioactive source to the tip of a nail that has a large, flat head. Lift this assembly through the hole in the window screening and into the cloud chamber using a drinking straw and stick the head of the nail to the magnet at the top of the glass. This arrangement will hold the source securely in place until you want to swap it for another one..