Cloud Chamber Demo
The cloud chamber, also known as the Wilson chamber, is used to visually detect
ionizing radiation through the condensation effect of supercooled, supersaturated alcohol
vapor. Carl D. Anderson, using such
a chamber, discovered the positron particle in 1932.
The Science and Engineering Club at Moorpark College hope to produce our own cloud
chamber experiment using a variety of on hand materials as the radiation source.
The estimated co
st for supplies is $300.00. Sales tax is included in this estimate.
Supplies will include plexi
glass for a five
sided cube enclosure, aluminum sheet metal,
black felt fabric, epoxy glue, dry ice, and concentrated ethanol solution. The device may
be run 2
4 times, depending on dry ice usage. Free pizza will be provided to participants
assisting in the chamber’s construction. Two large pizzas are estimated at a cost of $25
with tax and delivery tip.
TOTAL ESTIMATED COST: $325
Chris Tuten Njian
SCIENCE AND ENGINEERING CLUB
The cloud chamber consists of an enclosure containing superchilled air, which is
supersaturated with ethanol alcohol. It works through the condensation effect of ionic
charges traveling through the supersaturated solution. Similar to the ‘trailing cloud
of high altitude airplanes, these particles act as condensation nuclei around which a mist
The chamber must be cooled to the cusp of condensation for the air
mixture, which is slightly above the temperature of dry ice (
). A five
acrylic cube is placed on top of an aluminum metal sheet to seal the enclosure from
external heat. Dry ice is placed below the metal sheet, which conducts heat away from air
inside of the enclosure until equilibrium is met roughly around th
e temperature of dry ice.
Since the system reaches equilibrium well below the condensation temperature of the
mixture, the desired effect is only temporary
on the order of 10
Several particles may be identified when using the cloud chamber und
uniform magnetic field. These include alpha, beta, and positron particles, each with their
own distinctive paths. Carl D. Anderson used a similar apparatus to discover the positron
particle in 1932.
Members of the Science and Engineering Cl
ub at Moorpark College seek to gain
on experience in science by applying theory learned in the classroom to build
The completed, working apparatus shall be donated to the physics department at
the end of the exper
iment. We hope it will serve as a useful aide in classroom discussions
on nuclear physics.
The design will utilize the following in its construction and operation:
Estimated Cost (dollars)
glass cube (
18’’ x 18’’ x 12’’)
Aluminum sheet metal (2’ x 2’)
呷漠污oge⁰楺za猠景s⁶潬畮 ee牳 楮捬畤i猠瑩瀩
glass cube is to be assembled as in figure 1. The sides are
adhered using epoxy glue. The cube is to be placed on a sheet of aluminum with dry ice
below the sheet. The radiation source will rest on black fe
lt to enhance the color contrast
of any condensation paths. Additionally, black felt may be placed on two of the sides for
even more contrast.
Special thanks to Scott MacLeod for his assistance in parts selection and
supplying the radia
tion source. His help has been invaluable.
I would also like to thank the contributors. The contributions of Elan Levy, Jack
Sun, Scott Selleh, and Steve Chenevert have been especially helpful.
Additional thanks are in order for Ben Champion for introdu
cing the cloud
chamber concept in the 11/16/2006 meeting of the Science and Engineering Club. We
appreciate his ideas and initiative.
President, Sci. and Engr. Club