Yesterday I decided to carry out a cloud chamber experiment for a school assessment. I used "100%" isopropanol and around 2.5 kg of dry ice. After a wait of approximately 30 minutes, the particle tracks began to appear. I placed a weak source of Americium-241 sourced from a smoke detector (1 μCi) in the chamber, expecting to see some thick alpha particle tracks, but instead got thin and short range tracks. What could these possibly be? Are they secondary particles produced by the small amount of gamma emission from Americium-241? The reason I am having so much difficulty identifying these is that the electrons or positrons have somewhat 'curved' or 'curly' tracks and are much longer. I have attached a video of the tracks, you may need to look closely as they are very small. Any help identifying these would be greatly appreciated. Thanks.