Wiki source code of Info collection for the BAM
Version 4.1 by cpassow on 2020/04/23 17:41
Show last authors
| author | version | line-number | content |
|---|---|---|---|
| 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}})) | ||
| 3 | |||
| 4 | \\ | ||
| 5 | |||
| 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 | ||
| 15 | |||
| 16 | \\ | ||
| 17 | |||
| 18 | * if DBC3 is not working then also 3DBC2 can be used. there is a linear correlation between BC2 and BC3 | ||
| 19 | |||
| 20 | \\ | ||
| 21 | |||
| 22 | === more Info: === | ||
| 23 | |||
| 24 | \\ | ||
| 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 | ||
| 29 | |||
| 30 | \\ | ||
| 31 | |||
| 32 | == Streak camera info == | ||
| 33 | |||
| 34 | \\ | ||
| 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 ...) | ||
| 39 | |||
| 40 | \\ | ||
| 41 | |||
| 42 | == Calculate pump-probe delay == | ||
| 43 | |||
| 44 | * BAM measurement: difference between electrons and timing system | ||
| 45 | ** the BAM signal has to be added, but it seems that the sign is the different for FLASH2 | ||
| 46 | ** it is the best to test addition/subtraction and check the results on a step function (more/less sharp) | ||
| 47 | |||
| 48 | * Streak camera: difference between electrons and optical laser | ||
| 49 | ** it is a slow signal and should only be used as a rolling average over multiple minutes | ||
| 50 | ** if you see a drift in the streak camera which you do not see in the BAM it is resulting from the optical laser | ||
| 51 | ** 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 | ||
| 52 | ** addition/subtraction is dependent on the setup and have to be checked |