Using PyLHC to Compute Calibration Factors¶
The bpm_calibration module of PyLHC can be used to compute BPM calibration factors. Only one entrypoints exists for both methods, the argument method can be used to select it, and defaults to beta. Using the script to make compute calibration factors through \(\beta\)-functions for instance from IP1 and IP5 goes as:
python -m pylhc.bpm_calibration \
--input <measurements directory> \
--output <output directory> \
--ips 1 5 \
--method beta
The provided input measurements directory needs to contain the TFS files with the beta functions obtained with the analysis done via omc3. The output directory will then contain, depending on the chosen method, TFS files for the calibration: calibration_{beta,dispersion}_{x,y}.tfs. See the API documentation for a detailed description of the code and the different parameters.
Nomenclature of Output Files¶
Calibration From the β-Function¶
The output TFS files produced via the \(\beta\) method contain the following columns:
| Column Name | Meaning | Calculation |
|---|---|---|
| S | Longitudinal Position | - |
| CALIBRATION | Calibration factor determined from \(\beta\)-functions | \(C^A_{x,y} = \sqrt{\frac{\beta^{\phi}_{x,y}}{\beta^A_{x,y}}}\) |
| ERROR_CALIBRATION | Error associated to the calibration factor from \(\beta\) | \({\left(\Delta C_{x,y}^{A}\right)^{2}} = \frac{\left(\Delta \beta_{x,y}^{\phi}\right)^{2}}{4 \beta_{x,y}^{A}\beta_{x,y}^{\phi}} + \frac{\beta_{x,y}^{\phi}\left(\Delta \beta_{x,y}^{A}\right)^{2} }{4(\beta_{x,y}^{A})^{3}}\) |
| CALIBRATION_PHASE_FIT | Calibration factor determined from fitting of the phase function | \(C^A_{x,y} = \sqrt{\frac{\beta^{\phi,fit}_{x,y}}{\beta^A_{x,y}}}\) |
| ERROR_CALIBRATION_PHASE_FIT | Error associated to the calibrator factor from \(\Psi\) | \(\left( {\Delta C_{x,y}^{A}}\right)^{2} = \frac{\left(\Delta \beta_{x,y}^{\phi,fit}\right)^{2}}{4 \beta_{x,y}^{A}\beta_{x,y}^{\phi,fit}} + \frac{\beta_{x,y}^{\phi,fit}\left(\Delta \beta_{x,y}^{A}\right)^{2} }{4(\beta_{x,y}^{A})^{3}}\) |
Calibration From the Dispersion Function¶
The output TFS files produced via the dispersion method contain the following columns:
| Column Name | Meaning | Calculation |
|---|---|---|
| S | Longitudinal Position | - |
| CALIBRATION | Calibration factor determined from dispersion function | \({C_{x}^{A}} = \frac{D^\phi_x}{D^A_x} = \frac{D^A_{N,x}\sqrt{\beta_{x}^{\phi}}}{D^A_{x}}\) |
| ERROR_CALIBRATION | Error associated to the calibration factor from dispersion | \(\left(\Delta {C^A_x}\right)^{2} = \left(\frac{\Delta D^\phi_x}{D^A_x}\right)^2 + \left(\Delta D^A_x \frac{D^\phi_x}{(D^A_x)^2}\right)^2\) |
| CALIBRATION_FIT | Calibration factor determined from fitting of the dispersion function | \({C_{x}^{A}} = \frac{D^{\phi,fit}_x}{D^A_x} = \frac{\left(D^A_{N,x}\sqrt{\beta_{x}^{\phi}}\right)^{fit}}{D_{x}^{A}}\) |
| ERROR_CALIBRATION_FIT | Error associated to the calibrator factor from dispersion fit | \(\left(\Delta {C^A_x}\right)^{2} = \left(\frac{\Delta D^{\phi,fit}_x}{D^A_x}\right)^2 + \left(\Delta D^A_x \frac{D^{\phi,fit}_x}{(D^A_x)^2}\right)^2\) |