Physics307L:People/DePaula/Notebook/070926

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Contents

Electron Diffraction

Goal

Provide a measurable display of particle/wave duality of the electron. Will will attempt these measurements by creating a beam of electrons that will diffract off of a thin graphite film and create a diffraction pattern on a luminescent screen. Another option is to use magic spells to create Level 2 particle/wave duality, and summon unicorns. Because I am a level 3 rogue and cannot summon unicorns, only lesser wildabeasts, we will use the former process.SJK 00:38, 20 October 2007 (CDT)
00:38, 20 October 2007 (CDT)You should cite Anne's notebook if she was able to use magic spells.
00:38, 20 October 2007 (CDT)
You should cite Anne's notebook if she was able to use magic spells.

Setup

SJK 00:40, 20 October 2007 (CDT)
00:40, 20 October 2007 (CDT)I think the explanation of the bias voltage in your summary is probably more correct.  The bias voltage is too low, I think, to have an effect on the electrons leaving the filament.
00:40, 20 October 2007 (CDT)
I think the explanation of the bias voltage in your summary is probably more correct. The bias voltage is too low, I think, to have an effect on the electrons leaving the filament.

We used the diagram provided to hook up the heater and a bias voltage to the electron gun. We require a bias voltage because the heater we are using does not provide enough energy. The bias voltage adds an underlying power level that the heater then builds upon. We turned on the heater and waited a couple minutes for the cathode to heat up, then we slowly raised the high voltage meter until green light appeared on the luminescent screen. We then turned on the bias voltage. After a few painful shocks we were able to adjust the bias voltage until there were two concentric green circles appearing on the luminescent screen. The bias voltage is set at 8 volts. The electron gun works by passing current through a conductive filiment creating heat and electrons which are pulled away from the cathode cylinder by the anode. The anode has a potential running through it that pulls electrons in a beam, out of the cathode and through the graphite target.

Data Collection

SJK 00:41, 20 October 2007 (CDT)
00:41, 20 October 2007 (CDT)
00:41, 20 October 2007 (CDT)

Starting with the Hight Voltage [HV] at 5kV we measure the difference between the two radii of the concentric green rings.

Trial # HV in kV Outer Diameter of Inner Ring Inner Diameter of Inner Ring Outer Diameter of Outer Ring Inner Diameter of Outer Ring
1 5.0 +/- 0.02 24.45mm 20.15 mm 39.51mm 36.48mm
2 4.8 +/- 0.02 24.8mm 20.49mm 42.37mm 38.41mm
3 4.6 +/- 0.02 25.47mm 21.22mm 43.32mm 38.58mm
4 4.4 +/- 0.02 26.45mm 21.32mm 45.17mm 38.54mm
5 4.2 +/- 0.02 27.58mm 22.75mm 45.32mm 40.49mm
6 4.0 +/- 0.02 28.29mm 23.03mm 41.33mm
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