99 lines
3.3 KiB
Markdown
99 lines
3.3 KiB
Markdown
## Channel list
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All PSSS data channels are listed in the following sheet:
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[Sheet of PSSS data channels](https://docs.google.com/spreadsheets/d/16Hz7MZR3E7-OmLHfakkT2K6yPMFUzp4eIFZxrzXWjFk/edit?usp=sharing)
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## Nomenclature
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| Style | Meaning |
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|-------|---------|
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| SARFE10-PSSS059:**SPECTRUM**\* | Raw spectral data |
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| SARFE10-PSSS059:**FIT**\* | Results of Gaussian fit |
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| SARFE10-PSSS059:**SPECT**\* | Statistics from the raw (without fit) spectrum |
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| SARFE10-PSSS059:**AVG**\* | Data calculated from average (not single shot) spectra |
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## Concepts
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**Width and center**
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Spectral width and central energy are calculated by both a Gaussian fit and directly from the spectra. Depending on the spectral intensity profile, the Gaussian may return a poor representation of the spectra, for example for a spectral with a long tail. Before both fitting and calculation the spiky single shot spectra are smoothed with a savgol filter:
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```plaintext
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# smooth the spectrum with savgol filter with 51 window size and 3rd order polynomial
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smoothed_spectrum = scipy.signal.savgol_filter(spectrum, 51, 3)
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```
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The standard deviation and center of mass for the spectra are calculated as:
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```plaintext
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smoothed_spectrum_normed = smoothed_spectrum / np.sum(smoothed_spectrum)
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spectrum_com = np.sum(axis * smoothed_spectrum_normed)
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spectrum_std = np.sqrt(np.sum((axis - spectrum_com) ** 2 * smoothed_spectrum_normed))
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```
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**Relative energy spread**
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Channels ending in **RES** are a measure of the relative energy spread in units of ‰. For **FIT** data the relative energy spread is calculated as:
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$`\frac{2.355*\sigma}{\mu}`$
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and for directly calculated values (**SPECT**):
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$`\frac{2.355*RMS}{\text{Center of mass}}`$
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where the factor or 2.355 is included to allow these values to be comparable.
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**Spectral brightness**
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To quantify an increase in the spectral intensity in a narrowing bandwidth the so called Spectral brightness is calculated:
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$`\text{Spectral brightness} = \frac{\text{Single shot intensity [uJ]}}{\text{Single shot spectral FWHM [eV]}}`$
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At Aramis the current channel used for the single shot pulse intensity is:
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`SARFE10-PBPG050:FAST-PULSE-ENERGY`
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and the spectral FWHM uses the single shot spectral width. The result channel name is:
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`<SPECTROMETER:DEVICE>:FIT-BRT`
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indicating the data uses a Gaussian fit. Beware this data is only meaningful if the spectral intensity distribution is near Gaussian.
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## Data flow schematic
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## CamServer setup
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The PSSS has a dedicated server - sf-daqsync-11.psi.ch
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### Store pipeline
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- SARFE10-PSSS059_store
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- 4 clients
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This pipeline sends the camera image directly to the image buffer
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**Channels**
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- SARFE10-PSSS059:FPICTURE
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### PSSS pipeline
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- SARFE10-PSSS059_psss
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- 13 clients
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This pipeline extracts the spectra, fits and produces the statistics
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**Channels**
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- SARFE10-PSSS059:FIT-BRT
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- SARFE10-PSSS059:FIT-COM
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- SARFE10-PSSS059:FIT-FWHM
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- SARFE10-PSSS059:FIT-RES
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- SARFE10-PSSS059:FIT-RMS
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- SARFE10-PSSS059:SPECT-COM
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- SARFE10-PSSS059:SPECT-RES
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- SARFE10-PSSS059:SPECT-RMS
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- SARFE10-PSSS059:SPECTRUM_X
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- SARFE10-PSSS059:SPECTRUM_Y
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- SARFE10-PSSS059:SPECTRUM_Y_SUM
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- SARFE10-PSSS059:processing_parameters |