THE USE OF THE WILSON CLOUD CHAMBER FOR MEASURING THE RANGE OF ALPHA‐PARTICLES FROM WEAK SOURCES

In December 1931, Harold Urey discovered deuterium (and its nucleus, the deuteron) by spectroscopically detecting the faint companion lines in the Balmer spectrum of atomic hydrogen that were produced by the heavy hydrogen isotope. In February 1932, James Chadwick, stimulated by the claim of the wife-and-husband team of Irène Curie and Frédéric Joliot that polonium alpha particles cause the emission of energetic gamma rays from beryllium, proved experimentally that not gamma rays but neutrons are emitted, thereby discovering the particle whose existence had been predicted a dozen years earlier by Chadwick’s mentor, Ernest Rutherford. In August 1932, Carl Anderson took a cloud-chamber photograph of a positron traversing a lead plate, unaware that Paul Dirac had predicted the existence of the anti-electron in 1931. These three new particles, the deuteron, neutron, and positron, were immediately incorporated into the experimental and theoretical foundations of nuclear physics.

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Determination of the Ranges and Straggling of Low-Energy Alpha Particles in a Cloud Chamber

Physical Review ◽

10.1103/physrev.96.673 ◽

1954 ◽

Vol 96 (3) ◽

pp. 673-678 ◽

Cited By ~ 1

Author(s):

S. Barile ◽

R. Webeler ◽

G. Allen

Keyword(s):

Alpha Particles ◽

Cloud Chamber ◽

Low Energy

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ENERGY SPECTRUM OF NEUTRONS FROM A THORIUM ACTIVE DEPOSIT – BERYLLIUM SOURCE

Canadian Journal of Physics ◽

10.1139/p51-015 ◽

1951 ◽

Vol 29 (2) ◽

pp. 129-136 ◽

Cited By ~ 2

Author(s):

D. A. Bromley

Keyword(s):

Angular Distribution ◽

Energy Spectrum ◽

Experimental Error ◽

Energy Levels ◽

Maximum Energy ◽

Alpha Particles ◽

Cloud Chamber

The energy spectrum of the neutrons emitted when beryllium is bombarded with alpha particles from Th (C + C′) has been determined by measuring the ranges and directions of recoil of protons produced in a cloud chamber by the neutrons. The maximum energy of the neutrons was found to be about 15.5 Mev., within experimental error of the calculated maximum, 14.4 Mev. Many neutrons were found with energy of about 2.15 Mev. and the structure in the remainder of the spectrum can be attributed to the existence of energy levels in C12 at about 7.1 and 4.5 Mev. The angular distribution of the protons scattered by the neutrons from this source was isotropic to within experimental error.

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