1.9 KiB
Channel list
All PSSS data channels are listed in the following sheet:
Nomenclature
| Style | Meaning |
|---|---|
| SARFE10-PSSS059:SPECTRUM* | Raw spectral data |
| SARFE10-PSSS059:FIT* | Results of Gaussian fit |
| SARFE10-PSSS059:SPECT* | Statistics from the raw (without fit) spectrum |
| SARFE10-PSSS059:AVG* | Data calculated from average (not single shot) spectra |
Concepts
Width and center
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:
# smooth the spectrum with savgol filter with 51 window size and 3rd order polynomial
smoothed_spectrum = scipy.signal.savgol_filter(spectrum, 51, 3)
The standard deviation and center of mass for the spectra are calculated as:
smoothed_spectrum_normed = smoothed_spectrum / np.sum(smoothed_spectrum)
spectrum_com = np.sum(axis * smoothed_spectrum_normed)
spectrum_std = np.sqrt(np.sum((axis - spectrum_com) ** 2 * smoothed_spectrum_normed))
Relative energy spread
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:
\frac{2.355*\sigma}{\mu}
and for directly calculated values (SPECT):
\frac{2.355*RMS}{\text{Center of mass}}
where the factor or 2.355 is included to allow these values to be comparable.