Difference: 20161104_MSciSpectroscopyMeeting (4 vs. 5)

Revision 504 Nov 2016 - WilliamBurrows

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META TOPICPARENT name="StewartBoogertSpectroscopy2016"
Peak Algorithm
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  • First attempt at error bars, setting y error as the square root of the count:
    Improved_Cd_0650_Gaussians_lowest_errorbar.png
  • Error bars are tiny due to incorrect assumption that data follows a poison distribution.
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  • Gaussian function used:
 \begin{equation} f(x) = a e^{- \frac{(x - \mu )^2}{2 \sigma ^2}} + b \end{equation}
 
  • Chi squared function used:
 \begin{equation} \chi2 = \sum \frac{(x_i - \mu)^2}{\sigma^2} \, . \end{equation}
  • Cd spectrum at 06.50mm with Gaussian fits, error bars and Chi squared values:
    Cd_0650_gaussian_errors_chi.png
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  • Array of test parameters passed to fucntion : test_array_Cd650 = [[8E6, 150, 30, 3E5], [1.6E7, 270, 30, 3E5], [1.6E7, 520, 30, 3E5]]
 
  • Chi squared values are huge as expected due to poor fit. Once errors and fit equation are correct, Chi squared should reduce.
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 -- JamesAngthopo - 03 Nov 2016

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META FILEATTACHMENT attachment="Improved_Cd_0650_Gaussians_lowest_errorbar.png" attr="" comment="First attempt at error bars, setting y error as sqrt of count" date="1478254666" name="Improved_Cd_0650_Gaussians_lowest_errorbar.png" path="Improved_Cd_0650_Gaussians_lowest_errorbar.png" size="22613" user="zyvb951" version="1"
META FILEATTACHMENT attachment="Cd_0650_gaussian_errors_chi.png" attr="" comment="Cd spectrum at 06.50mm with Gaussian fits, error bars and Chi squared values" date="1478262095" name="Cd_0650_gaussian_errors_chi.png" path="Cd_0650_gaussian_errors_chi.png" size="50103" user="zyvb951" version="1"
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META FILEATTACHMENT attachment="gaussian_fit.py.txt" attr="" comment="Gaussian, erro, chi squared pyhton code" date="1478267403" name="gaussian_fit.py.txt" path="gaussian_fit.py.txt" size="6243" user="zyvb951" version="1"
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