Science Buddies: "Ask an Expert"

Hello,

I'm conducting a project on Reducing Cosmic Ray Penetration. I was planning on using a Wilson Cloud Chamber for the experimentation. I would have an ambient trial, where I would measure the amount of particles that appear in a traditional Cloud Chamber. Then, I plan on covering the chamber in different combination of materials to reduce particle penetration.

Here's the problem 1: In most of the Cloud Chambers I have come so far, they have one source of light. Does this mean that I can only see the portion of particles coming from the opposite direction? For example, I came across this <http://www.amnh.org/education/resources ... cloud.html>, which shows a simplfied diagram with the light source coming from the right side. If I look at the chamber from the front, will I only be able to capture an image of the particles coming from the left side? Or will the particles coming from all sides show up in the image?

The second issue: Is there any recommendations to where a student can get [borrow or buy] aerospace grade metal [enough to cover a fish tank]? I've attempted to contact several companies, all of which have not replied [probably because the metal is so expensive].

Thank you for helping!

I know a few people in the plane business so I've dashed off some emails - no promises on that though. You might also try contacting some of the places that reclaim the materials out of dead aircraft. They're often referred to as 'boneyards'. Here's one site with a list: http://www.airplaneboneyards.com/airpla ... nd-map.htm . The skin of a plane is pretty thin and I can't see why the material would be that expensive. If you explain what you want and why, perhaps you can convince someone to loan you a hunk of a plane they're recycling.

Aircraft are basically made of good quality materials and you can easily buy good quality aluminum and other metals an metalworking supply shops. For the purposes of a science fair experiment any piece of aluminum about 2mm thick would be a good substitute for real airplane skin. The 727 skin varies between 1.8 and 2.2mm depending on where it is.

How big is your fish tank? If you have one 12 inches tall, you'd need one square foot of metal of each linear foot of circumference. A 10 gallon tank is 20" long and 11" wide, so the circumference is 20+11+20+11 = 62 inches. I picked a random online metal dealer and priced a 62" x 12" piece of 2mm aluminum and it was about $65.00. Thinner metal is cheaper, obviously, and maybe someone with more specific knowledge can advise you on using thicker metal vs foil (which is quite cheap).

Someone else here with more (and by that I mean any) experience with cloud chambers will have to help you with your first question.

Howard

Hello Mr. Howard,

Thank you so much for the quick reply! I'll look into the 'boneyards' to see if there's any promising leads.

My fish tank is rather big (12 in tall), but depending on the amount of material I am I able to get, I can easily change the size. I was looking into less of a thinner material, since the basics of radiation is that the thicker and denser the material, the less the particle will penetrate.

Anyways, thank you again for your help!

Good luck with your calls. Be persistent but not annoying. Most companies would be happy to help a student with research if you politely explain what you need and why.

If you get really stuck, aluminum foil sold in the grocery is about 0.2mm thick. Wrapping that around your tank 10 times would be the rough equivalent of the skin on an airplane.

Howard