Chadwick's Neutron Chamber, replica of Cavendish Lab apparatus
date: label: Date made
content: ca. 1960 (original 1932)
name: label: manufacturer
content: University of Cambridge. Department of Physics. Cavendish Laboratory
label: originator
content: Chadwick, James
notes: label: Description
content: Chadwick's Neutron Chamber, replica of Cavendish Lab apparatus. Object ID EM.N-08022. Overall: length 15.5 cm x width 6 cm x height 14 cm.
label: Description
content: Object consists of a brass tube. In the original apparatus, the tube contained a polonium (source of alpha particles) at one end and a berylium target.
label: Description
content: (See 1st object on right in accompanying image).
label: Description
content: History and basic principle
label: Description
content: In their attempts to excite and transform atomic nuclei physicists were limited throughout the 1920s to bombarding them with the particles--chiefly alpha-particles -- spontaneously emitted by naturally radioactive substances. This was irksome to physicists, not least because of the limited supply and great expense of radium and similar substances, but also because of the limited energy and uncontrollability of these spontaneous radiations. However, the era of hamstrung nuclear physics before the advent of accelerators ended on an unexpected upbeat: the discovery of the neutron in 1932.
label: Description
content: Object EM.N-08022 is a replica of the neutron chamber used by James Chadwick in 1932 at the Cavendish Laboratory, Cambridge University, England in his first experiments demonstrating the existence of the neutron. In his experiments, the neutron chamber served as the neutron source and was used in conjunction with a separate ionization chamber.
label: Description
content: Rutherford had long anticipated the existence of an uncharged particle of about the mass of a proton, and members of his Cambridge research group had repeatedly sought for it. Chadwick recognized evidence of it in I. and F. Joliot-Curie’s description of phenomena resulting from the bombardment of beryllium by alpha-particles.
label: Description
content: At one end of the chamber's brass tube, polonium emiited alpha particles, which then struck a berylium target causing particles to be emitted from the other end of the tube. The emitted particles entered an adjacent ionization chamber in which their identity could be confirmed as Rutherford's hypothesized neutron.
label: Description
content: See: https://www.aps.org/publications/apsnews/200705/physicshistory.cfn - for a brief historical account of Chadwick's career, including his association with Ernest Rutherford at the Cavendish Laboratory, as well as his experimental confirmation of Rutherford's speculation on the existence of the neutron (for which Chadwick was awarded the Nobel Prize in 1935).
label: Description
content: Also see Chadwick's publication:
label: Description
content: Chadwick, James, The Existence of a Neutron, Proceedings of the Royal Society, A.136(830) 692-708.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, Cambridge
label: Associated Place
content: United Kingdom: England, Cambridge
topic: label: general subject association
content: Science & Scientific Instruments
label: general subject association
content: Modern Physics
setName: label: See more items in
content: Medicine and Science: Modern Physics
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content: Science & Mathematics
creditLine: label: Credit Line
content: Cavendish Laboratory
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.N-08022
label: catalog number
content: N-08022
label: accession number
content: 224580
objectType: label: Object Name
content: Neutron Chamber
physicalDescription: label: Measurements
content: overall: 14 cm x 6 cm x 15.5 cm; 5 1/2 in x 2 3/8 in x 6 3/32 in