Last modified by sndueste on 2025/02/06 10:58
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1 1  * the relevant data is the Arrivaltime FLASH.SDIAG/BAM/4DBC3/LOW_CHARGE_ARRIVAL_TIME
2 -* besides the arivaltime 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))
2 +* besides the arivaltime 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}}))
3 3  
4 4  \\
5 5  
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17 17  
18 18  * if DBC3 is not working then also 3DBC2 can be used. there is a linear correlation between BC2 and BC3
19 19  
20 +=== more Info to the BAM: ===
21 +
22 +* [[LINK to detailed infos from MSK (may only work inside DESY network)(% class="confluence-embedded-file-wrapper confluence-embedded-manual-size" %)~[~[image:url:http://hasfweb.desy.de/pub/TWiki/TWikiDocGraphics/external-link.gif~|~|width="13" height="12"~]~]>>url:http://www.desy.de/~~mbock/pages/BAM_daq_channel_descriptions.html||rel="nofollow" shape="rect" class="external-link"]]
23 +* [[talk by Marie (2011)>>attach:FLASH-seminar-2011_BAM_study_results.pdf]]
24 +* contact: Marie Kristin Czwalinna
25 +
20 20  \\
21 21  
22 -=== more Info: ===
28 += General information for the data analysis of pump-probe experiments =
23 23  
24 24  \\
25 25  
26 -* [[LINK to detailed infos from MSK (may only work inside DESY network)(% class="confluence-embedded-file-wrapper confluence-embedded-manual-size" %)~[~[image:url:http://hasfweb.desy.de/pub/TWiki/TWikiDocGraphics/external-link.gif~|~|width="13" height="12"~]~]>>url:http://www.desy.de/~~mbock/pages/BAM_daq_channel_descriptions.html||rel="nofollow" shape="rect" class="external-link"]]
27 -* [[talk by Marie (2011)>>attach:FLASH-seminar-2011_BAM_study_results.pdf]]
28 -* contact: Marie Kristin Czwalinna
32 +please have a close look to the publication:
29 29  
34 +Evgeny Savelyev, et al,  //Jitter-Correction for IR/UV-XUV Pump-Probe Experiments at the FLASH Free-Electron Laser//,
35 +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"]]
36 +
37 +describing in detail the usage of BAM, streak camera and delay line data in order to get the actual time axis as reliable as possible.
38 +
30 30  \\
31 31  
41 +Here is a summary of the ideas:
42 +
32 32  == Streak camera info ==
33 33  
45 +* the streak camera measures the delay between optical (amplified) laser and FEL (dipole radiation). - not in respect to the master clock !
46 +* streak camera ONLY delivers data which is averaged over several 10 seconds. There is NO shot to shot info.
47 +* a larger value of the streak camera delay (typically) indicates that the optical laser comes later than the FEL (or FEL earlier than the laser ...)
48 +
34 34  \\
35 35  
36 -* the streak camera measures the delay between optical (amplified) laser and FEL (dipole radiation). - not in respect to the master clock !
37 -* streak camera ONLY delivers data which is averaged over several 10 seconds. there is NO shot to shot info.
38 -* a larger value of the streak camera delay indicates that the optical laser comes later than the FEL (or FEL earlier than the laser ...)
51 +\\
52 +
53 +{{info title="Correction of pump-probe delay"}}
54 +* BAM measurement: difference between electrons and timing system
55 +** usually the BAM signal has to be added to the delay ...
56 +** 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
57 +* Streak camera: difference between electrons and optical laser
58 +** it is a slow signal and should only be used as a rolling average over multiple minutes
59 +** if you see a drift in the streak camera which you do not see in the BAM it is resulting from the optical laser
60 +** if this (BAM - streak camera signal) is significant e.g. 200 fs over 1 h, it means the drift compensation was probably off and it should be compensated
61 +** addition/subtraction is dependent on the setup and have to be checked
62 +{{/info}}