Download Wilson - Klemmer

C.T.R. Wilson
Charles Wilson is 2nd from right in the front row.
Can you find Paul Langevin and O.W. Richardson?
MAJOR INTERESTS
Cloud Chamber
Atmospheric
Electricity
first chamber
x-ray photos
1895
Meteorological Society
employment
1899
first photos of
particles
1911
Observer in Met. Physics
Solar Physics Observatory
appointed 1913
2 major papers
with illustrations
published 1923
promoted to Reader
of Electrical Meteorology
1918
Nobel Prize
with Compton
1927
published "Theory of
Thundercloud Electricity"
1956
“the most original and
wonderful instrument in
scientific history.”
- Rutherford
• ALPHA
broad, straight track
• BETA
thin, bending track
• GAMMA no tracks as too few ions are
produced in the air
1911 photo
1912 Wilson photo
Compton Scattering : What?
• X-ray photons
collide with
electrons in
carbon atoms.
• The scattered
photons are
shifted to
longer
wavelengths
(lower
energies).
Compton Scattering : So What?
 = h (1-cos)
me c
• The particle theory of light was still controversial
in the 1920’s, despite Einstein’s photoelectric
effect.
• Compton used a particle model of the photon, and
classical conservation of momentum, to explain
the shift in wavelength of the observed scattered
x-rays.
• evidence of Compton Effect (Nobel Prize Compton &
Wilson 1927)
• evidence of transmutation of elements (Rutherford’s
N +  -> O + p)
• discovery of positron and the pair creationannihilation of electrons & positrons (Nobel Prize
Anderson 1936)
• discovery of muon
Beyond the Cloud Chamber
• P. BLACKETT “counter controlled cloud chamber” (Nobel
Prize 1948) added a Geiger Counter above & below the c.c.
Cosmic rays triggered gas expansion and their own photos
when impulses hit both counters simultaneously.
• D.A. GLASER “bubble chamber” replaced the c.c. in 1952,
using liquid He or H2. Higher density medium allowed
photos of high-E particles that were too fast for the c.c.
Web
Resources
• http://home.houston.rr.com/molerat/cloud.htm
how to make a cloud chamber
• http://www.nobel.se/physics/laureates/1948/pres
s.html Wilson’s Nobel address
• http://hyperphysics.phyastr.gsu.edu/hbase/quantum/comptint.html#c1
Compton Effect
• http://www.boltlightningprotection.com/lightni
ng_physics.htm lightning physics