The chamber is filled with
super-saturated alcohol vapor. The end of the needle holds an
alpha source. The
emitted alpha particles leave visible trails of condensation in their
paths.
This happens because the high energy particles ionize other particles
they
encounter, which provide nucleation sites at which the vapor condenses.
NOTES
To prepare chamber: Soak
blotter
paper in alcohol and place around perimeter of chamber. Pour some
alcohol on black cardboard base, without letting it pool. Warm
chamber in your
hands to vaporize alcohol and displace water vapor. Place cork
with
needle in side hole so that the tip of the needle is as close as
possible to the bottom of the chamber. Place chamber on styrofoam
plate, pour liquid nitrogen into the plate and watch for vapor trails.
Dim room lights and illuminate
from the side by shining flashlight through gap in blotter paper.
