Chapter3_20 - According to classical theory the oscillating...

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PHY3063 R. D. Field Department of Physics Chapter3_20.doc University of Florida Compton Scattering (1) The first direct evidence of the existence of photons was presented by A.H. Compton in 1923 . He directed a monochromatic beam of X-rays ( i.e. electromagnetic radiation) with wavelength, λ 0 , at a thin block of carbon and studied the intensity and wavelength of the scattered radiation as a function of the angle θ . He found that in addition to the wavelength λ 0 , which occurred at all angles, there was another component λ 1 which was longer than λ 0 . The amount of wavelength shift, ∆λ = λ 1 λ 0 , was the same regardless of the target material, implying that the effect involved electrons rather than the atom as a whole. Also ∆λ increased as the scattering angle θ increased. Classical Wave Theory:
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Unformatted text preview: According to classical theory the oscillating electric field of the incoming wave would set electrons in the target material into oscillations. These vibrating electrons would then reradiate electromagnetic waves in all directions, but at the same wavelength as the incident wave ( i.e. ). Compton Model: Compton adopted the suggestion by Einstein that light comes in parcels ( i.e. photons) with energy and momentum given by E = hf = hc/ and p = h/ He then calculated the properties of photon-electron 2-to-2 scattering + e- + e-using relativistic energy and momentum conservation, treating the photon as a massless particle, . 1 Incident X-ray Detector Carbon Block Wavelength x-axis y-axis z-axis E B Direction of Propagation 1...
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This note was uploaded on 05/29/2011 for the course PHY 3063 taught by Professor Field during the Spring '07 term at University of Florida.

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