The image intensifier in the SQS Exit Slit imager had been exchanged on request of SQS, Thomas Baumann.
Model: Hamamatsu MCP C9546-03-Y001 against C9546-01.
The position of the YAG screen on the camera is slightly shifted which may slightly affect the spectral axis, a few pixels vertically, and approximately 15 pixels horizontally.
The image scale by zoom had not been changed, as before 13 µm/pixel.

The SA3 FEL imager is now protected via the Big Brother server, which creates a beam limit on the bunch pattern server if necessary.
contact Andreas Koch, Lars Fröhlich for more details or consult the imager manual, section 2.9:
https://docs.xfel.eu/share/page/site/xfelwp74/document-details?nodeRef=workspace://SpacesStore/1766b430-7c48-4c46-bb2d-1774d69e1246
demonstration 27.1.2025 to Jan Grünert, Harald Sinn, Andreas Galler.

Function: The Big Brother limits the number of pulses in SA3 via a beam limit in case of danger, individually for each screen of the FEL imager, AND only if an imager screen is inserted. The EPS is valid as before.
This means that if the EPS interlock for the FEL imager is enabled (default setting, 2 pulses maximum), the intervention by the Big Brother could reduce pulses to 1 or 0.
The potential limit of the number of pulses for each screen is shown in the FEL imager scene, as before.

Best practice: Use the GATT to limit the pulse energy. Avoid to operate with a strongly saturated image. Use low absorbing ND filters.

eLogs posts to: eLog Operation-2025,  Zulip SASE3_INSTRUMENT_COMMISSIONING, ttfinfo

Beam Downtime

During last night, apparently the photon beam was down in all SASE beamlines during two longer periods:

• between 2:48am and 3h23am (35 min) on 14.4.2025
• between 5:09am and 6h59am (1 hour 50 min) on 14.4.2025

X-ray delivery

• 11.0 keV, up to 178 pulses at 564 kHz, 650 uJ.

Optical laser delivery

• illumination and pp lasers

Achievements/Observations

• Performed detector and ice detection program.

Issues

• Run Controller was crashing several times during the day. DOC was notified. They discovered that the run controller server was down and fixed the problem by restarting it.
• PP laser was not available during the day until ~ 18:30
• Some troubles with and homing of SmarAct stages after update from to the current control version. DOC was requested to roll back to the latest stable release.

X-ray delivery

• 11.0 keV, up to 352 pulses at 1.1 MHz, 900 uJ.

Optical laser delivery

• ns illumination and pp lasers

Achievements/Observations

• Finished with Ice detection program
• Optimized the beamline alignment for the next experiment
• Checked the NKB focusing with CRL collimation: The collimated scheme resulted in smaller focus size and significantly higher intensity at focus

Issues

• PAM mirror mount is not reacheable with the SmarAct motor

X-ray delivery

• up to 202 pulses per train (~1 mJ pulse energy), 0.5 MHz.

Optical laser delivery

• PP laser aligned to the interaction point

Achievements/Observations
Preparation for user beamtime

• x-ray beam aligned and focused
• gotthard II ready
• PP laser aligned and ready
• ns laser aligned and ready
• inline mic aligned
   

X-ray delivery

• up to 202 pulses per train (~1.4 mJ pulse energy), 0.5 MHz.

Optical laser delivery

• OPO issue in the late shift
• PP laser aligned and timed both at the interaction point and in PAM

Achievements/Observations

• gotthard II used and working
• PP laser aligned and timed
• PAM aligned and timed

Issues

• issue with the OPO when we wanted to collect data

To do for next shift

• collect lysozyme for geometry and start user program

Damage on FEL imager was also seen by our morning shift around 7:50am.

SPB/SFX 7955 Shift 1
**X-ray delivery**
* up to 202 pulses per train (~1.4 mJ pulse energy), 0.5 MHz.

**Optical laser delivery**
* 420nm used for sample excitation. timed to 1ps with water jet interaction
* difficult to find good filter combination for jet illumination laser and pump laser

**Achievements/Observations**
* 10.8 keV - 11.2 keV energy scan
* lysozyme geometry data set
* several runs for sample dark data set (potentially more needed)
* a few runs for 1ps pumped data set (definitely more needed)

**Issues**
* difficult end to shift (nozzle and illumination issues)
* hit rate rather low for timing program (leads to long processing times)

**To do for next shift**
* continue user data set including power titration
* start time delay sequence

SPB/SFX 7955 Day 2

**X-ray delivery**
* up to 202 pulses per train (~1.4 mJ pulse energy), 0.5 MHz.
* A few beam downs toward the end of the shift

**Optical laser delivery**
* 420nm used for sample excitation. timed to 1ps with water jet interaction

**Achievements/Observations**
* x-ray beam de-focused to a few um for data taking
* PP laser aligned and timed
* runs for 1ps pumped data set
* good peak distribution at 11% transmission (100 CVD/ 200 CVD / None / 3200 CVD)
* hit rate better than previous day

**Issues**
* a lot of nozzle exchange
* sample most likely accumulating on the catcher entrance window
* DAMNIT issue with too many queued jobs, fixed by Oleksii (OCD)

**To do for next shift**
* finish power titration and continue with other time points

SPB/SFX 7955 Day 3

X-ray delivery

• up to 202 pulses per train (~1.4 mJ pulse energy), 0.5 MHz.

• One longer down toward the end of the shift

Optical laser delivery

• 420nm used for sample excitation. timed to 1ps with water jet interaction

Achievements/Observations

• x-ray beam de-focused to a few um for data taking

• PP laser aligned and timed

• runs for 1ps, 100ps and 100ns pumped data sets

• hit rate much better (even > 10%) than previous day with small crystals

Issues

• a lot of nozzle exchange in the morning

• DAMNIT issue with too many queued jobs – some of the earlier jobs timed out

SPB/SFX 7955 Day 4

X-ray delivery

• up to 202 pulses per train (~1.4 mJ pulse energy), 0.5 MHz

• stable

Optical laser delivery

• 420nm used for sample excitation. timed to 1ps with water jet interaction

• PAM set up for time points <1 ps

• From 19:15 to 21:15 (100 uJ/cm2 data point) the feedback loops were off resulting in higher intensity fluctuations, resolved at 21:52

Achievements/Observations

• x-ray beam de-focused to a few um for data taking

• PP laser aligned and timed

• PAM calibrated and used with YAG sample surviving 13% transmission

• power titration at 100ns and fluences 13 mJ/cm2, 25 mJ/cm2, 100 mJ/cm2 and 191 mJ/cm2

• delays 100 fs and 500 fs

• good peak distribution at 13% transmission (None / None / None / 3200 CVD)

• hit rate around 6%

Issues

• problems with catcher alignment after clean up

X-ray delivery

    up to 352 pulses per train (~1.9 mJ pulse energy)@9.3 keV, 0.5 MHz ans 1.1 MHz. Beamdown for 40 min.

Optical laser delivery

    800 nm, less than 20 fs at sample position, no issue

Achievements/Observations

    X-ray beam de-focused to a few um for data taking

    PP laser aligned and timed

    1 hours data collection

Issues

    AGIPD gain map was strange, some gain changes was observed without X-ray

    Data was not migrated -> DRC was called and informed

X-ray delivery

    up to 202 pulses per train (~1.9 mJ pulse energy)@9.3 keV, 0.5 MHz

Optical laser delivery

    800 nm, less than 20 fs at sample position, no issue
    

Achievements/Observations

    X-ray beam de-focused to a few um for data taking

    PP laser aligned and timed

    runs for -1 ps - 1.5 ps

    Very stable jet

Issues
    No major issue

X-ray delivery

    up to 202 pulses per train (~1.9 mJ pulse energy)@9.3 keV, 0.5 MHz

Optical laser delivery

    800 nm, less than 20 fs at sample position, no issue

Achievements/Observations

    X-ray beam de-focused to a few um for data taking

    PP laser aligned and timed

    runs for -1 ps - 1.5 ps

    Very stable jet

Issues

    No major issue

X-ray delivery

    up to 202 pulses per train (~1.9 mJ pulse energy)@9.3 keV, 0.5 MHz

Optical laser delivery

    800 nm, less than 20 fs at sample position, no issue

Achievements/Observations

    X-ray beam de-focused to a few um for data taking

    PP laser aligned and timed

    runs for -1 ps - 1.5 ps

    Very stable jet

    PAM was installed

X-ray delivery
-12.4 keV, 202 pulses, 0.5 MHz, 1mJ/pulse

Optical laser delivery
- ns laser (660 nm wavelength) for jet illumination

Achievements/Observations
- NKB focus optimized
- One PCS user program successfully finished
- Second PCS user program was just started

Issues
- Right before we could start with beam defocusing, the beam was gone around 8:45 pm. BKR called to let us know that there will be no beam today (cryo issues)

X-ray delivery

• 12.4 keV, 1.1mJ/pulse, 202 pulses/train at 0.56MHz
• Focused NKB beam was used

Optical laser delivery

• ns laser for jet visualization

Achievements/Observations

• Successfully finished all PCS beamtimes
• Stable jet with PEO sheath

Issues

• No beam in the morning
• Unstable jet with ethanol sheath

SPB/SFX shift summary user experiment 8039

**X-ray delivery**
-15 keV with Hirex monitoring, 0.5 mJ/pulse, 202 pulses/train at 0.56 MHz pulse repetition rate

**Optical laser delivery**
-810 nm laser for illumination

**Achievements/Observations**
- Collected sample data for ca. 2h 15min using a DFFN 
- XTD2 CRLs optimized and realigned
- Offset mirror M1/M2 optimized for 15 keV
- Repositioned the illumination fiber inside IRU chamber
- Germanium blades were installed for the IRU_Slit_4 (top and bottom)

**Issues**
- PP laser alignment could not be pursued as hexapod had to be repositioned first (interaction region was too close to exit cone)

X-ray delivery
-15 keV with Hirex monitoring, 0.5 mJ/pulse, 202 pulses/train at 0.56 MHz pulse repetition rate
Optical laser delivery
- 810 nm laser for illumination
-PP laser for excitation, 590 nm, 51 pulses, 141 kHz
Achievements/Observations

• Collected high resolution time resolved data
• Collected Tve_CPC500f and Tve_CPC1n data and completed Tve_CPC20p