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Unformatted text preview: Alex Ryng Lab Partner: Daniel Harburg Date lab performed: 10/30/07 Physics 321 Professor Watson High resolution optical spectroscopy ABSTRACT The ratio of m d /m p can be experimentally determined to within 1% using the high resolution SPEX Model 1704 spectrometer. Using a table of numerically precise fundamental constants and spectra of hydrogen and deuterium sources, the deuteron to proton mass ratio, with associated uncertainty, is experimentally determined to be 1.98 0.02. Familiarity with uncertainty propagation, both in estimates and procedures, and the high resolution of the spectrometer yield a result with very low uncertainty. I. INTRODUCTION 1 Using the modern high-resolution SPEX Model 1704 spectrometer, controlled by a microprocessor, high resolution spectra of various sources in the 1750 to 15000 range are easily obtained. Inside the spectrometer, the grating and mirror positions are set up in a Czerny-Turner configuration. Light passing through the entrance slit travels through the Czerny-Turner configuration in the spectrometer and eventually passes through the exit slit into a photomultiplier tube. The movable grating allows for wavelengths of different lengths to pass through the photomultiplier. The photomultiplier output travels through auxiliary electronics that transform the output pulses into a voltage. The voltage, plotted as a linear function of light intensity, appears as a spectrum on the oscilloscope Using the SPEX Model 1704 spectrometer to obtain high-resolution spectra of the Balmer series emissions lines of the hydrogen and deuterium atoms, precise measurements of spectral lines permit a determination of the deuteron to proton mass ratio to within a 2% uncertainty. II. PROCEDURE Setting up the spectrometer, source and auxiliary electronics as shown in Fig. 1, we started with a high-resolution spectrum of an Hg source, setting our scan range from 3133.1 to 3134.1. At first we only adjusted the entrance and exit slits to optimize light intensity since the Hg source was stationary. With the hydrogen and deuterium sources, both the slits and the positioning of the source relative to the entrance slit, beam...
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This note was uploaded on 11/10/2008 for the course PHYS 321 taught by Professor Dunham during the Spring '08 term at Middlebury.
- Spring '08