Physics307L:People/Ozaksut/Notebook/070926

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--Anne Ozaksut 18:45, 26 September 2007 (EDT)

Electron Diffraction

  1. 1 Goal

We wish to verify the wave properties of matter by trying to produce a diffraction pattern of electrons that we beam through a graphite diffraction grating onto a luminescent screen.

  1. 2 Equipment

Electron Diffraction Tube (EDT) Power supply for the heater in the EDT Power supply for the the anode in the EDT Multimeter to monitor current

  1. 3 Notes

Electron Diffraction Lab Manual Better Electron Diffraction Lab Manual Our electron diffraction tube consists of an electron gun (a heater, a cathode, an anode), a diffraction grating, and a vacuum bulb with a screen on the back. The heater heats the cathode, which is some thin sheet of metal, exciting electrons and releasing them from the material. The electrons then are accelerated and directed toward the diffraction grating by an anode, which is another material whose voltage we can change in order to change the velocity of our electrons. The diffraction grating is a thin graphite film that the electrons should interfere with each other after passing through, similar to light, if the theory is correct. The electrons then travel to the back of the bulb, and if they interfere with each other, we should see a diffraction pattern on the luminescent screen.

  1. 4 Setup

We connected our power supply to the EDT. The same voltage is applied to both the heater and the anode. We connect a power supply (bias voltage) to the grating, so that only the electrons with the most momentum will make it through the diffraction grating. The positive charge on the anode accelerates the electrons toward the screen, and the positive charge on the grating captures the weakest electrons. When we change the high voltage on the EDT, we change the speed of the electrons, which changes the momentum, energy, and wavelength. We will try to determine the relationship between the diffraction pattern, wavelength, polycrystalline diffraction grating properties, and velocity.

  1. 5 Data

Here is the link to Day 1 Data, which we will use today. Day 1 Data

Voltage in kV Inner/Inner Outer/Inner Inner/Outer Outer/Outer
5 18.69 25.05 37.78 43.30
4.9 20.79 24.8 40.14 43.08
4.8 19.82 24.91 39.81 43.58 started ,measuring horizontally
4.7 20.04 25.29 38.75 43.69
4.6 21.35 25.91 39.31 45.99
4.5 21.76 26.79 41.08 46.94
4.4 21.91 27.27 41.86 46.97
4.3 21.98 28.97 41.69 48.95
4.2 23.41 28.02 42.64 49.41
4.1 24.86 28.75 44.08 50.12
4.0 25.45 28.19 46.74 51.57
3.9 25.17 29.68 46.94 51.87
3.8 26.22 30.62 46.69 52.22
3.7 26.24 31.68 47.68 53.83
3.6 27.75 32.85 47.85 52.43
3.5 28.85 33.57 48.09 52.84
3.4 28.48 35.30 50.06 53.59
3.3 29.12 36.1 50.37 54.31
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