Wiki source code of Info collection for the BAM
Version 10.1 by sndueste on 2022-09-07 17:39
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| author | version | line-number | content |
|---|---|---|---|
| 1 | == Some basic stuff: == | ||
| 2 | |||
| 3 | * (% style="color: rgb(255,0,0);" %)The relevant data is the arrival time FLASH.SDIAG/BAM/4DBC3/LOW_CHARGE_ARRIVAL_TIME | ||
| 4 | * (% style="color: rgb(255,0,0);" %)Besides the arrival time from FLASH1 there is also the FLASH2/3 electron arrival time saved. The BAM data is saved for the complete RF pulse. First bunches are from FLASH1 then there is a gap for switching and then there is a second part for FLASH2 (starting at the FLASH2 start time (recorded in DAQ as {{code language="none"}}/FL2/Timing/start time flash2{{/code}})) | ||
| 5 | * (% style="color: rgb(255,0,0);" %)There are LOW and HIGH charge channels. For now the LOW_CHARGE Channel is the relevant one. | ||
| 6 | * (% style="color: rgb(255,0,0);" %)Bigger numbers indicate later arrival time of the electrons | ||
| 7 | * (% style="color: rgb(255,0,0);" %)The arrival time should be within -20 ps and +20 ps - otherwise there might be a problem ... | ||
| 8 | * ((( | ||
| 9 | (% style="" %) | ||
| 10 | (% style="color: rgb(255,0,0);" %)The actual time t0 = 0ps is an arbitrary offset which is only changed after setting up the system after, e.g., a maintenance time, and has no relevance. | ||
| 11 | |||
| 12 | (% style="" %) | ||
| 13 | (% style="color: rgb(255,0,0);" %)What one usually does, after defining/finding time zero in the experiment, is either observe the relative changes for a single bunch during the course of the measurement run compared to the starting point, | ||
| 14 | |||
| 15 | (% style="" %) | ||
| 16 | (% style="color: rgb(255,0,0);" %)or (in addition) observe the relative deviation across all bunches within the same bunch train. | ||
| 17 | |||
| 18 | (% style="" %) | ||
| 19 | (% style="color: rgb(255,0,0);" %)Those deviations and drifts happen usually only in the order of 50fs to 200fs; depending on the machine setup. | ||
| 20 | |||
| 21 | (% style="" %) | ||
| 22 | (% style="color: rgb(255,0,0);" %)The short-term timing jitter (over several 100 trains) for each individual bunch, i.e. the standard deviation from their mean value, is usually ~~ 20fs. | ||
| 23 | |||
| 24 | (% style="" %) | ||
| 25 | (% style="color: rgb(255,0,0);" %)The actual measurement resolution of a BAM can be - currently - as good as 3fs, for each bunch in the full train. | ||
| 26 | ))) | ||
| 27 | |||
| 28 | == Data structure == | ||
| 29 | |||
| 30 | (% style="color: rgb(0,0,0);" %)The details about the functionality and the data structure can be found on the page: (%%)**[[ BAM Data Structure>>url:https://confluence.desy.de/display/SDiagPublic/BAM+Data+Structure||shape="rect"]]** | ||
| 31 | |||
| 32 | \\ | ||
| 33 | |||
| 34 | = Publications related to BAM = | ||
| 35 | |||
| 36 | === BAM principle === | ||
| 37 | |||
| 38 | 1. (% style="color: rgb(23,43,77);" %)A. Angelovski, et al.(%%) | ||
| 39 | (% style="text-align: left;" %)//Evaluation of the cone-shaped pickup performance for low charge sub-10 fs arrival-time measurements at free electron laser facilities | ||
| 40 | //(% style="color: rgb(23,43,77);" %)Phys. Rev. ST Accel. Beams (% style="text-align: left;" %)**18**(% style="color: rgb(23,43,77);" %), 012801 (2015)(%%) | ||
| 41 | [[https:~~/~~/doi.org/10.1103/PhysRevSTAB.18.012801>>url:https://doi.org/10.1103/PhysRevSTAB.18.012801||style="text-align: left;" rel="nofollow" shape="rect"]] | ||
| 42 | |||
| 43 | \\ | ||
| 44 | |||
| 45 | === Two publications showing how to use the BAM data to improve the time resolution: === | ||
| 46 | |||
| 47 | 1. Evgeny Savelyev, et al, | ||
| 48 | //Jitter-Correction for IR/UV-XUV Pump-Probe Experiments at the FLASH Free-Electron Laser//, | ||
| 49 | New J. Phys. **19**, 043009 (2017), [[https:~~/~~/doi.org/10.1088/1367-2630/aa652d>>url:https://doi.org/10.1088/1367-2630/aa652d||shape="rect"]]\\ | ||
| 50 | 1. ((( | ||
| 51 | Dennis Mayer, Fabiano Lever and Markus Gühr, | ||
| 52 | //Data analysis procedures for time-resolved x-ray photoelectron spectroscopy at a SASE free-electron-laser//, | ||
| 53 | J. Phys. B: At. Mol. Opt. Phys. **55**, 054002 (2022); [[https:~~/~~/doi.org/10.1088/1361-6455/ac3c91>>url:https://doi.org/10.1088/1361-6455/ac3c91||style="text-decoration: none;" shape="rect"]] | ||
| 54 | ))) | ||
| 55 | |||
| 56 | === Publications showing the correlation between the values measured by the BAM and the XUV pulse arrival time === | ||
| 57 | |||
| 58 | 1. (% style="color: rgb(0,0,0);" %)//** Description of the FLASH synchronization system**// | ||
| 59 | S. Schulz, et al.(%%) | ||
| 60 | (% style="text-align: left;" %)//Femtosecond all-optical synchronization of an X-ray free-electron laser//(% style="color: rgb(0,0,0);" %),(%%) | ||
| 61 | (% style="color: rgb(0,0,0);" %)Nature Communications (% style="text-align: left;" %)**6**(% style="color: rgb(0,0,0);" %), 5938 (2015); (%%)[[http:~~/~~/dx.doi.org/10.1038/ncomms6938>>url:http://dx.doi.org/10.1038/ncomms6938||style="text-decoration: none;text-align: left;" shape="rect"]] | ||
| 62 | \\ | ||
| 63 | 1. //**Showing a correlation of 11 fs rms between BAM and XUV arrival time | ||
| 64 | **//R. Ivanov, et al to be published 2022 //** | ||
| 65 | \\**// | ||
| 66 | 1. ((( | ||
| 67 | //**Showing a correlation of 20 fs rms between BAM and XUV arrival time**// | ||
| 68 | R. Ivanov, J. Liu, G. Brenner, M. Brachmanski and S. Düsterer, | ||
| 69 | //FLASH free-electron laser single-shot temporal diagnostic: terahertz-field-driven streaking//, | ||
| 70 | Special Issue (PhotonDiag2017), | ||
| 71 | J. Synchrotron Rad.** 25**, 26-31 (2018);[[ https:~~/~~/doi.org/10.1107/S160057751701253X>>url:https://doi.org/10.1107/S160057751701253X||style="text-decoration: none;" shape="rect"]]//** | ||
| 72 | **// | ||
| 73 | ))) | ||
| 74 | 1. ((( | ||
| 75 | //**Study of arrival time fluctuations**// | ||
| 76 | Ivette J. Bermúdez Macias, Stefan Düsterer, Rosen Ivanov, Jia Liu, Günter Brenner, Juliane Rönsch-Schulenburg, Marie K. Czwalinna, and Mikhail V. Yurkov, | ||
| 77 | //Study of temporal, spectral, arrival time and energy fluctuations of SASE FEL pulses//, | ||
| 78 | Optics Express 29, 10491-10508 (2021); [[https:~~/~~/doi.org/10.1364/OE.419977>>url:https://doi.org/10.1364/OE.419977||style="text-decoration: none;" shape="rect"]] | ||
| 79 | ))) | ||
| 80 | |||
| 81 | \\ | ||
| 82 | |||
| 83 | \\ | ||
| 84 | |||
| 85 | {{info title="Correction of pump-probe delay"}} | ||
| 86 | * (% style="color: rgb(255,0,0);" %)BAM measurement: difference between electrons and timing system | ||
| 87 | ** (% style="color: rgb(255,0,0);" %)usually the BAM signal has to be added to the delay ... | ||
| 88 | ** (% style="color: rgb(255,0,0);" %)it is the best to test addition/subtraction and check the results on a step function (more/less sharp) - if there is no change of the data with + and - there is anyway something wrong. please contact your local contact for more information / help | ||
| 89 | {{/info}} |