RHUL Physics Department TWiki> Public Web>UserList>StewartBoogert>StewartBoogertAstronomy>StewartBoogertMSciProjects>StewartBoogertSpectroscopy2016>20161104_MSciSpectroscopyMeeting (04 Nov 2016, WillBurrows) EditAttach

- Found peak using second derivative of data. Double differential used as it enables us to find some hidden peaks.
- Picked a cut off point for second derivative of data to give a range, and , where the values inside the range would be considered a peak
- Used equation,

- RMS was obtained by the equation,

- FWHM can be obtained by .

- Peak locator algorithm used for camera angle at 1.50mm:

- First attempt at error bars, setting y error as the square root of the count:

- Error bars are tiny due to incorrect assumption that data follows a poison distribution.

- Gaussian function used:

- Chi squared function used:

- Cd spectrum at 06.50mm with Gaussian fits, error bars and Chi squared values:

- 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.

- gaussian_fit.py.txt: Gaussian, erro, chi squared pyhton code

I | Attachment | Action | Size | Date | Who | Comment |
---|---|---|---|---|---|---|

png | Cd_0650_gaussian_errors_chi.png | manage | 48.9 K | 04 Nov 2016 - 12:21 | WillBurrows | Cd spectrum at 06.50mm with Gaussian fits, error bars and Chi squared values |

png | Improved_Cd_0650_Gaussians_lowest.png | manage | 19.6 K | 04 Nov 2016 - 10:17 | WillBurrows | Zoomed in look at the lowest Cd peak at 06.50mm |

png | Improved_Cd_0650_Gaussians_lowest_errorbar.png | manage | 22.1 K | 04 Nov 2016 - 10:17 | WillBurrows | First attempt at error bars, setting y error as sqrt of count |

png | PeakAt1.50mm.png | manage | 95.1 K | 03 Nov 2016 - 20:39 | JamesAngthopo | Peak locator algorithm used for camera angle at 1.50mm |

txt | gaussian_fit.py.txt | manage | 6.1 K | 04 Nov 2016 - 13:50 | WillBurrows | Gaussian, erro, chi squared pyhton code |

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Topic revision: r5 - 04 Nov 2016 - WillBurrows

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