Tuesday, July 3, 2018

particle physics - How come I never see cosmic rays in steam like they appear in a cloud chamber?


I just put like half a cup of water in a mason jar and put that in the microwave and accidentally left it in there for to long and it got boiling hot, then when I took it out and let it cool of course the glass cooled much quicker near the top away from the boiling liquid, and there was some very thick nice steam, one other variable is it's pretty cold in my house today. Anyways looking at the steam in the jar I was reminded of a cloud chamber I once saw which could detect cosmic rays, but looking at the steam closely for several minutes I didn't see any. Come to think of it I've NEVER seen cosmic rays in clouds that I've uhm... "created" so what is the difference between what I can make with a jar and a microwave, and what scientists make for cr detection? And as a bonus question how could the microwave/ water jar set up possibly be improved?



Answer




Cloud chambers require a supersaturated environment such as one created by cooling a sealed chamber filled with alcohol vapor. The high velocity cosmic ray particles ionize the gas molecules they come in contact with. This causes the gas particles to condense at those places leaving a visible trail. Steam in a microwave would not usually be supersaturated.


A simple cloud chamber can be created by using a sealed container (ie 10 gallon fish tank, large glass/plastic jar, etc) with a cloth/sponge saturated with alcohol at the top and dry ice under the container. The alcohol will evaporate saturating the air near the top, as it is cooled below that it becomes supersaturated.


http://www.sciencefriday.com/educational-resources/build-a-cloud-chamber/


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