Last modified by sndueste on 2025/02/06 10:58
From version 10.1
edited by sndueste
on 2022/09/07 17:39
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To version 1.1
edited by sendels
on 2019/08/09 12:46
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1 -XWiki.sndueste
1 +XWiki.sendels
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1 -== Some basic stuff: ==
1 +* [[LINK to detailled infos from MSK~[~[image:url:http://hasfweb.desy.de/pub/TWiki/TWikiDocGraphics/external-link.gif~|~|width="13" height="12"~]~]>>url:http://mskwiki/index.php?title=BAM-DAQ_Channels||shape="rect"]]
2 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.
3 +\\
11 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,
5 +* the relevant data is the Arrivaltime FLASH.SDIAG/BAM/4DBC3/LOW_CHARGE_ARRIVAL_TIME
14 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.
7 +\\
17 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.
9 +* There are now (since March 2017) LOW and HIGH charge channels. for now the LOW_CHARGE Channel is the relavant one.
20 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.
11 +\\
23 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 -)))
13 +* bigger numbers indicate later arrivaltime of the electrons
27 27  
28 -== Data structure ==
15 +\\
29 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"]]**
17 +* the arrivaltime sould be within -20 ps and +20 ps . otherwise there might be a problem ...
31 31  
32 32  \\
33 33  
34 -= Publications related to BAM =
21 +* There is a BAM status parameter: FLASH.SDIAG/BAM/4DBC3/BAM_STATUS.1 (the 1 indicates FLASH1)
22 +** bit 0 (value: 1) = data is valid,
23 +** bit 1 (value: 2) = at least 1 bunch is present,
24 +** bit 2 (value: 4) = calibration is on,
25 +** bit 3 (value: 8) = internal feedback is on,
26 +** bit 4 (value: 16) = tuning mode is on
35 35  
36 -=== BAM principle ===
28 +\\
37 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"]]
30 +* if DBC3 is not working then also 3DBC2 can be used. there is a linear correlation between BC2 and BC3
42 42  
32 +(from Marie: der groesste Drift-Beitrag kommt immer aus dem Injektor (also alles zw. Injektorlaser und ACC39) Einfluss von ACC23 ist deutlich kleiner. Im Mittel hat man einen linearen Zusammenhang zw. Ankunftszeit BC2 zu BC3.)
33 +
43 43  \\
44 44  
45 -=== Two publications showing how to use the BAM data to improve the time resolution: ===
36 +\\
46 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 -)))
38 +=== more Info: ===
55 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 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 80  
42 +* [[talk by Marie (2011)>>attach:FLASH-seminar-2011_BAM_study_results.pdf]]
43 +* contact: Marie Kristin Czwalinna
44 +
81 81  \\
82 82  
47 +== Streak camera info ==
48 +
83 83  \\
84 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}}
51 +* the streak camera measures the delay between optical (amplified) laser and FEL (dipole radiation). - not in respect to the master clock !
52 +* streak camera ONLY delivers data which is averaged over seveal 10 seconds. there is NO shot to shot info.
53 +* a larger value of the streak camera delay indicates that the optical laser comes later than the FEL (or FEL earlier than the laser ...)