Wiki source code of Info collection for the BAM

Version 10.1 by sndueste on 2022/09/07 17:39
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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.
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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,
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15 (% style="" %)
16 (% style="color: rgb(255,0,0);" %)or (in addition) observe the relative deviation across all bunches within the same bunch train.
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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.
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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.
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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"]]**
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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"]]
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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 )))
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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}}