X-ray delivery

• 10 keV, up to 128 pulses with custom bunch pattern, 1.6-2.0 mJ

Optical laser delivery

• NA

Achievements/Observations

• Collected first SFX data, but background on JUNGFRAU is rather high and needs further optimisation.

Issues

• AGIPD having frequent problems with both MFPGAs (once even both at the same time). Frequent restarts were needed.
• Horizontal drift of the beam pointing.

X-ray delivery

• 10 keV, up to 160 pulses at 1.1MHz, 1.8 mJ

Optical laser delivery

• NA

Achievements/Observations

• Instrument aligned up to IRDa at 10 keV.
• Focus optimised.
• JUNGFRAU timed.

Issues

• We could only start using the beam at 1 am.
• More mirror movement needed to get the beam down the instrument than expected.
• Several AGIPD power cycling needed due to issues with MFPGA2

Stable seeding with 1mJ + 400mJ SASE
HIREX triggered interlock when all attenuators are removed 
successful test of nano focusing setup
successful test and alignment of x-ray microscopes
Alignment of split and delay line
Laser x-ray timing at sample position

5.61 keV setpoint in SA1 was confirmed to correspond to 5.660 keV (+/- 0.003 keV), see attached.

The user expt #5644 can proceed as planned.

Not sure if this is the cause of the fringes reported before, but at 5.6 keV there are clear cracks visible on the XTD2 Attenuators 75 umm and 150um CVD, see attached. There is also a little bit of damage on the 600 um CVD, but not as strong as the others.

At 5.6 keV we will need to use the thin attenuators. I will mention again in case this causes problems downstream.

Edit 8:50h: We do not observe additional interference effects in the downstream beam profile (see attachement 4)

The status of the XTD2 attenuators has been checked during the experiment last week and many were found to cause disturbances in the wavefront ranging from mild to severe.

Attachment 1: No attenuator
Attachment 2: 75 um CVD - Fringes visible in beam
Attachment 3: 150 um CVD - Strong fringes in beam
Attachment 4: 300 um CVD - Looks more or less ok
Attachment 5: 600 um CVD - Weak distortion in the beam profile
Attachment 6: 1200 um CVD - Ok
Attachment 7: 2400 um CVD - Ok
Attachment 8: 500 um Si - Not ok

Shift summary for 2024-02-25 from 11:00 to 2024-02-25 at 14:00:

Self-seeding at 8.5 keV, with approximately 500 μJ per pulse. 

Overall, the performance of x-ray self-seeding remains good, and users are happy. Pointing stability is also exceptional. However, enhancing photon energy slightly (600 uJ as we had yesterday) would further improve the signal-to-noise ratio.

Key Achievements and Current Challenges:

1. Ongoing data accumulation.
2. Issue with the sample motor (stepper motor). The encoder ceases to update values although the motor is actually moving. While a temporary workaround has been implemented, a thorough investigation is needed post-beamtime. More details: [Link]

X-ray delivery

• 9.10 keV; 190 pulses per train @1.1 MHz with roughly 170-200 uJ; stable delivery

Optical laser delivery

• ns laser for particles visualization

Achievements/Observations

• Sample injection and data collection for ~11 hours
• collected data on copper cubes with better hit rates than previous shifts; ~15%

Issues

• We had laser interlock issues, the magnet in door went to error state and this was fixed by Klaus Witt call around 22:15.
• data migration issues; it was very slow and DOC did not figure out the cause for this.

Shift summary for 2024-02-24 from 07:00 to 2024-02-25 at 14:00:

Self-seeding at 8.5 keV, with approximately 500 μJ per pulse. Following re-tuning around 10 am on the 25th, the energy per pulse increased to around 600 μJ.

The x-ray intensity and pointing stability have been excellent, resulting in a substantial amount of data being acquired by users just two days into the beamtime. Users have expressed satisfaction with the performance thus far.

There were a couple of brief beam downtimes, but they had minimal impact on beamline operations.

Achievements:

• Successful laser delay scan (0 - 1000 ps) of wire compression dynamics under ultra-intense laser interaction (>10^21 W.cm-2).
• Nanofocus Z scan imaging completed.
• Online analysis tools (DAMNIT) are functioning properly.
• Some minor issues with the automatic shot procedure using MDL were encountered but mostly resolved.
• Ongoing issues persist with the off-axis-parabola mirror X axis (motor movement not stopping), which will require follow-up after the beamtime.
• A minor issue was identified with laser timing jumps, possibly stemming from a trainID distribution issue with the ToD system. Increasing the sequence delay of the master timer from 10 to 30 appears to have mitigated this problem.

X-ray delivery
9.10 keV; 190 pulses per train @1.1 MHz with roughly 140-200 uJ; observed some fluctuation in the photon flux

Optical laser delivery
ns laser for particles visualization

Achievements/Observations

• Beam optimization and characterization
• X-ray focus FWHM calculation found to have a bug in pixel size used
• Sample injection and data collection for >10 hours
• collected data on copper cubes with average hit rates of ~5%

Issues

• DAQ - multiple crashes and restarts needed throughout the shift; at certain point we encountered three crashes within less than an hour; and called DAQ to intervene
• Gotthard II at Hirex stopped acquiring and we had to change the number of the acquisition time to ~10 days to allow continuous running until the end of the beamtime.
• hit rates were low and sonication of samples needed to be done several time to prevent clogging issues
• Focus drift - we observed significant drift in the beam; a refocus then had to be check several times to focus back the beam to nm
• beam intensity fluctuated a lot during the shift

Shift summary 2024-02-23 07:00 - 2024-02-24 10:00

We got self-seeding at 8.5 keV very quickly after changeover from 10.5 keV operation finished at 2024-02-23 07:00.
Pulse energy ~ 600 uJ. 

Progress is in general good. Most of planned tasks for the day are done.
We called BKR whether we can get a bit more energy/pulse this morning, but it appears difficult. Otherwise, having a bit more energy would be helpful to have enough signal-to-noise ratio for X-ray imaging. 

Achievements: 

• Insert nanofocus lens, pump IC1 sample chamber into vacuum
• Establish X-ray axis, measure source point and divergence
• Set up the CRL scheme overfilling CRL4b nanofocus (the settings used in Feb at 8.2 keV were CRL1 arm 3,5 and CRL2 arm 1)
• Bring the imaging systems to the X-ray axis
• Focus and calibrate the x-ray spectrometers
• Laser-xray timing verified on YAG
• DAMNIT setup 
• Nanofocus imaging optimization (Z-scans) with Cu 25um wire and Siemens star
  • Best focus was identified
• Sample alignment 

X-ray delivery:

stable and flat over 190 pulses per train. 1.1 MHz with ~200 uJ

Optical laser delivery:

NA

Achievements/Observations:

Beam optimization and characterization
Sample injection and data collection for ~10 hours

reasonable hit rates observed but highly fluctuating, making alignment optimisation slow

Issues:
DAQ - restarts needed throughout the shift
Sample injection - copper samples dont give high hit rate and increaseing sample concentration led to clogging
Focus drift - focus was tuned at around 3:30 pm ( from 4 um back to 1.5 um)
-again at 19:30 when we checked again focus was >2microns FWHM returned to 1.5

X-ray delivery: stable and flat over 190 pulses per train. 1.1 MHz with 200 uJ short intervention needed to improve intensity after it dropped

Optical laser delivery: NA

Achievements/Observations:

• Beam optimization and characterization
  - Short pulses tuned and number of spikes reduced
• X-ray focus FWHM calculation found to have a bug in pixel size used
  - rest to 0.2 FWHM of focused beam now better than 1.5 microns
• Laser illumination installed to enable particle visualization to aid alignment and feedback
• Sample injection and data collection for several hours
  - Hits seen from Silver cubes
  - very low hit rate from copper
  - cubes, and spheres

Issues:

• DAQ - multiple crashes and restarts needed throughout the shift
• Proc pipeline - some runs fail to processwhile adjacent runs collected with same conditions (run repeater) process without errors
• Sample injection - copper samples continue to be difficult to inject
  - very low hit rates (few hits seen per run)
  - clogging issues
• Focus drift - focus was tuned at around 3 pm, by 9 when we could check again focus was >3 microns FWHM
• Beam intensity reduced during the shift and BKR needed to tune it back
  - returned intensity to 200 uJ - they asked if we wanted to continue but did not as this could have resulted in more SASE spikes

Beam conditions:

• Used photon energies between 6 and 7 keV, including short undulator scans
• Continuously got 1 mJ despite the short pulse mode that's running
• Bandwidth was found to be 18 eV FWHM at 6.07 keV (0.3%) by monochromator scan against fixed undulator setpoint

Achievements:

• Cr foil scan for energy calibration of the FXE mono
• Prepared setpoints for XAS scans during next week's user expts. at: Ce L3 (5.72 keV), Ce L2 (6.16 keV) and Mn K (6.54 keV)
• IPM calibration against XGMD

Issues:

• ATT MDL (class JJAttenuator) got stuck in INIT state and then did not show that absorber was inserted in the beam path (ticket to be submitted to Ctrls)
• DA3 of FXE DAQ (FXE_DAQ_DATA/DA/3) got stuck in changing state (it got too many parameters inserted). The restart by shutting down the server and waiting for the device to come back up took around 20 mins, see 22.2.2024, 4:24 am to 4:43 am.

X-ray delivery: stable and flat over 250 pulses per train. 1.1 MHz with 400 uJ

Optical laser delivery: NA

Achievements/Observations:

• Beam optimization and characterization
  - Short pulses tuned
  - HIREX setup and used to characterize the number of SASE SPIKES per pulse (~10)

Issues

• 10 SASE spikes per pulse is more than desired
  - discussion with BKR and AccRC regarding possibilities for optimization (feedback in the morning)
  -HIREX data proc is not correct as dark processing fails

  - DOC informed and working on it
  - one issue was gothard II appeard to have timed out - does the number of triggers need increasing?
  -sample jetting setup

  - electrospray working but saw exactly 1 hit in run 32
  - tried to alighn with silver nano-cubes but had to switch to sucrose to increase hit rate to aid alignment
  - no hits with sucrose seen with scanning X +- 1mm

The cross on the FEL imager, which we use as a reference for BKR crew, is not centred on the GATT aperture. when was this changed, and why?

att. 1 and 2 show the current position (the saturated image aids the positioning of the GATT aperture).

att. 3 is from two weeks ago. then, the cross was centred on the GATT aperture.

X-ray delivery

• 1 to ~332 pulses at 6 keV, 4.5 mJ
• Stable delivery
• Number of pulses limited by the Photon Beam Power local limit that is set to 16 W. Is this intentional? All other limits are set to 40 W

Achievements/Observations

• Aligned NKB trajectory
• Achieved NKB focus
• Reduced background scattering on AGIPD
• Started data collection

Issues

• Identified a couple of problems with the new DAQ that we were testing. Controls group informed and investigating

*Achievements :
- Generally rather successful with very high quality beam parameters
- We had a nearly steady 800 uJ+ HXRSS flux during the user run and ~ 4mJ SASE during the setup at HED.
- Beampointing was rather stable throughout the HXRSS operation.
- Users took several shots (>2600 FEL and FEL+ReLAX shots) on target. The beamline setup was very quick prior to that and users were able to get preliminary data to prototype parameters already a day before formal handover to them and could straight go to harvest mode on Saturday morning.  
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* Issues :
- Users still found large Bremsstrahlung fluxes on their background, but this is rather on our side, in conjunction with the users.
- On the last day, we had issues with JF calibrations due to the high run numbers in the proposal. DOC promptly helped out.  
- Initially, we observed fluctuations in the FEL flux. BKR was very prompt to correct for this and user operation was not impacted seriously. Slow drifts in pulse energy were also observed, but again, could be compensated from time to time by them.
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Like after the previous winter maintenance period, the shutter of FXE appears as opened in DOOCS panels even though it is closed (https://in.xfel.eu/elog/OPERATION-2023/58).