• Predominantly experimental week; took spectrum images for 4 remaining lamps
  • Started aligning mirrors and focusing laser onto fibre end
Peak Finder
  • Plot of differential of data for Cadmium lamp with the grating of 6.50mm:
    diff.png

  • Plot of second differential of data for Cadmium lamp with grating of 6.50mm:
    doublediff.png

  • Normalised plot:
    mdatadiff.png

  • Normalised plot of all 3 sets of data:
    allnor.png

  • Test of peak finder algorithm:
    peakfinder.png

  • Need to find the weighted average for the location of the peaks for each batch of peak lines; so instead of obtaining multiple vertical lines for each peak in data you obtain one which is the average of group of data at the location. Also need to find the width of data.
Gaussian Fits

  • Attempted to fit multiple Gaussian curves to a spectrum using peak parameters attained by eye, looking at the spectrums, in the form [amplitude, pixel position, width, background]

  • Gaussian fits to the Cadmium 6.50mm spectrum:
    Cd_0650_Gaussians.png
  • Peak guess parameters passed to the function were [8E6, 150, 30, 3E5], [1.6E7, 270, 30, 3E5], [1.6E7, 520, 30, 3E5]

  • Gaussian fits to the Cadmium 1.50mm spectrum:
    Cd_0150_Gaussians.png
  • Peak guess parameters passed to the function were [8E5, 20, 40, 6E5], [8E5, 75, 20, 6E5], [2E6, 150, 30, 6E5], [1.6E6, 190, 30, 6E5], [9E5, 200, 30, 6E5], [1E6, 310, 20, 6E5], [1E6, 320, 30, 6E5], [1.6E6, 470, 20, 6E5], [1E6, 560, 30, 6E5], [8E5, 750, 30, 6E5]
  • Struggles with small, duplets or closely packed peaks

  • Limited Gaussian fits to the Cadmium 1.50mm spectrum:
    Cd_0150_Gaussians_2.png
  • Range for each fit is +/- 30 pixels from pixel position passed to the function

-- WillBurrows - 20 Oct 2016

Topic attachments
I Attachment Action Size Date Who Comment
PNGpng Cd_0150_Gaussians.png manage 65.5 K 20 Oct 2016 - 21:56 WilliamBurrows Gaussian fits to the Cadmium 1.50mm spectrum
PNGpng Cd_0150_Gaussians_2.png manage 65.2 K 21 Oct 2016 - 13:20 WilliamBurrows Limited Gaussian fits to the Cadmium 1.50mm spectrum
PNGpng Cd_0650_Gaussians.png manage 39.9 K 20 Oct 2016 - 21:56 WilliamBurrows Gaussian fits to the Cadmium 6.50mm spectrum
PNGpng allnor.png manage 100.1 K 21 Oct 2016 - 00:35 JamesAngthopo Normalised plot of all 3 sets of data
PNGpng diff.png manage 55.7 K 21 Oct 2016 - 00:33 JamesAngthopo Plot of differential of data
PNGpng doublediff.png manage 62.3 K 21 Oct 2016 - 00:34 JamesAngthopo Plot of second differential of data
Texttxt gaussian_fit.py.txt manage 1.6 K 20 Oct 2016 - 22:06 WilliamBurrows Current Gaussian fit python code
PNGpng mdatadiff.png manage 77.0 K 21 Oct 2016 - 00:34 JamesAngthopo Normalised plot
PNGpng peakfinder.png manage 59.7 K 21 Oct 2016 - 00:35 JamesAngthopo Test of peak finder algorithm

Physics WebpagesRHUL WebpagesCampus Connect • Royal Holloway, University of London, Egham, Surrey TW20 0EX; Tel/Fax +44 (0)1784 434455/437520

Topic revision: r5 - 21 Oct 2016 - WilliamBurrows

 
This site is powered by the TWiki collaboration platformCopyright © 2008-2018 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding RHUL Physics Department TWiki? Send feedback