demonstrational cloud chamber
Datecirca 1935
Inventory Number1997-1-0387
ClassificationCloud Chamber
Subject
Maker
Central Scientific Company
1889 - 2000
User
Bowdoin College, Department of Physics
founded after 1794
Cultural Region
Place of Origin
Place of Use
Dimensions18 x 19 x 29 cm (7 1/16 x 7 1/2 x 11 7/16 in.)
Material
DescriptionAn apparatus consisting of a triagular metal base with a column on one of its ends rising vertically augmenting in diameter in two steps. This column holds a cloud chamber from the bottom by a curved rod, and from the top by a metal clamp. The cloud chamber itself consists of a cylindrical glass chamber enclosed on top by a glass disk secured to the chamber by a steel ring and screws that extend to the bottom of the glass chamber, where it is secured to a metal casting in the shape of an inverted cone. At the base of this cone is a rubber, pear-shaped bulb. An electric light illuminates the glass chamber.
Signedon plaque: CENTRAL SCIENTIFIC Co / LABORATORY APPARATUS / SUPPLY CHEMICALS / CHICAGO, U.S.A / NEW YORK, BOSTON, TORONTO, LOS ANGELES
FunctionA cloud chamber was used to track (visualize) and study charged particles. To this effect, a chamber was filled with a gas (actually a mixture of vapor in equilibrium with liquid) and a non-condensating gas. To make the elementary particles (in this case known as cosmic rays) appear as visible tracks, the mixture described had to be brought into a supersaturated state by forcing the gas to expand. When this happened, condensation started around the ions generated by the passing of high-energy charged particles. The resulting droplets, the visible tracks, were then photographed.
This particular chamber was a commercial version for demonstrational purposes. During its use, the bulb and inverted cone would contain water up to a point about 1cm below the glass. Inside of the chamber would be a glass tip with a small amount of radium salt protected from contact with the water. For making the tracks visible, the operator would slowly push the bulb, and then suddendly release it. The drop in pressure inside the chamber would make the air supersaturated, at which point tracks would show up with the radioactive source as their origin.
This chamber could generate an electric field for clearing the tracks, could be located near a magnet for making the ray's paths curve according to their electric charge, and its water could be dyed black for providing contrast to the cloud tracks when seen from above.
A video explanation and demonstration of a cloud chamber's function and operation by the Fondazione Scienza e Tecnica in Florence is available on Youtube here.
This particular chamber was a commercial version for demonstrational purposes. During its use, the bulb and inverted cone would contain water up to a point about 1cm below the glass. Inside of the chamber would be a glass tip with a small amount of radium salt protected from contact with the water. For making the tracks visible, the operator would slowly push the bulb, and then suddendly release it. The drop in pressure inside the chamber would make the air supersaturated, at which point tracks would show up with the radioactive source as their origin.
This chamber could generate an electric field for clearing the tracks, could be located near a magnet for making the ray's paths curve according to their electric charge, and its water could be dyed black for providing contrast to the cloud tracks when seen from above.
A video explanation and demonstration of a cloud chamber's function and operation by the Fondazione Scienza e Tecnica in Florence is available on Youtube here.
ProvenanceFrom the Department of Physics, Bowdoin College.
B. F. Skinner
Date: circa 1950
Accessories: wire screens (4); electric cord; plastic bag containing a piece of wire and metal connections (orange and white wire)
Object number: WJ1233
National Institute of Mental Health
Date: circa 1998
Accessories: computer (2004-1-0403b); computer screen with mask (2004-1-0403c); plus a control box; spare Plexiglas touchscreen mask; food pellet distributor
Object number: 2004-1-0403a
Scientific Prototype Manufacturing Corporation
Date: 1960
Accessories: manual: <i>Laboratory Studies in the Analysis of Behavior</i> by Homme and Klaus (1957)
Object number: 2008-1-0003
Lehigh Valley Electronics
Date: 1980-1990
Accessories: two multiwire gray cables; 1 loose black wire; a removable wire mesh tray
Object number: 1998-1-0013
Hellige, Inc.
Date: 1949-1960
Accessories: wooden box
flexible black rubber tube with rigid white plastic connector at one end and a bulb-shaped glass chamber at the other end
metal pin with hardened red-rubber cap
Object number: 2003-1-0093
