Last modified by sndueste on 2025/02/06 10:58
From version 9.1
edited by sndueste
on 2022/09/07 11:46
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To version 3.1
edited by sndueste
on 2020/04/08 15:01
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Summary

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1 -=== Some basic stuff: ===
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 as {{code language="none"}}/FL2/Timing/start time flash2{{/code}}))
2 2  
3 -* The relevant data is the arrival time FLASH.SDIAG/BAM/4DBC3/LOW_CHARGE_ARRIVAL_TIME
4 -* 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 -* There are LOW and HIGH charge channels. For now the LOW_CHARGE Channel is the relevant one.
6 -* Bigger numbers indicate later arrival time of the electrons
7 -* The arrival time should be within -20 ps and +20 ps - otherwise there might be a problem ...
4 +\\
8 8  
9 -=== Data structure ===
6 +* There are now (since March 2017) LOW and HIGH charge channels. for now the LOW_CHARGE Channel is the relavant one.
7 +* bigger numbers indicate later arrivaltime of the electrons
8 +* the arrivaltime sould be within -20 ps and +20 ps . otherwise there might be a problem ...
9 +* There is a BAM status parameter: FLASH.SDIAG/BAM/4DBC3/BAM_STATUS.1 (the 1 indicates FLASH1)
10 +** bit 0 (value: 1) = data is valid,
11 +** bit 1 (value: 2) = at least 1 bunch is present,
12 +** bit 2 (value: 4) = calibration is on,
13 +** bit 3 (value: 8) = internal feedback is on,
14 +** bit 4 (value: 16) = tuning mode is on
10 10  
11 -(% 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"]]**
12 -
13 13  \\
14 14  
15 -= General information for the data analysis of pump-probe experiments =
18 +* if DBC3 is not working then also 3DBC2 can be used. there is a linear correlation between BC2 and BC3
16 16  
17 17  \\
18 18  
19 -please have a close look to the publication:
22 +=== more Info: ===
20 20  
21 -Evgeny Savelyev, et al,  //Jitter-Correction for IR/UV-XUV Pump-Probe Experiments at the FLASH Free-Electron Laser//,
22 -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"]]
24 +\\
23 23  
24 -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.
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
25 25  
26 26  \\
27 27  
28 -Here is a summary of the ideas:
29 -
30 30  == Streak camera info ==
31 31  
32 -* the streak camera measures the delay between optical (amplified) laser and FEL (dipole radiation). - not in respect to the master clock !
33 -* streak camera ONLY delivers data which is averaged over several 10 seconds. There is NO shot to shot info.
34 -* 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 ...)
35 -
36 36  \\
37 37  
38 -\\
39 -
40 -{{info title="Correction of pump-probe delay"}}
41 -* BAM measurement: difference between electrons and timing system
42 -** usually the BAM signal has to be added to the delay ...
43 -** 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
44 -* Streak camera: difference between electrons and optical laser
45 -** it is a slow signal and should only be used as a rolling average over multiple minutes
46 -** if you see a drift in the streak camera which you do not see in the BAM it is resulting from the optical laser
47 -** 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
48 -** addition/subtraction is dependent on the setup and have to be checked
49 -{{/info}}
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 ...)