Bunch pattern SA1 / SA3

SQS requests to change the bunch pattern.
Currently SA1/SA3 run interleaved as 131313...
The first bunch in the train (for SA1, non-lasing in SA3) nevertheless is visible as a small pre-peak in the diode signal which SQS uses to check the timing.
Therefore SQS requests to change to 31313131....

It was checked with SA1 (SPB/SFX) and the accelerator experts that this should not cause any issues (AGIPD detector is running on dynamic trigger),
therefore it was agreed that SPB/SFX informs BKR when there is a good moment without data acquisition, and BKR will make this change after informing SQS.
This change will happen within the next hour (as of 15h20).

started initial alignment for the ptycho experiment 
Continued with XPCS measurement using the levitation device

issues: contribution of the 2nd harmonic of 8 keV at 16 keV visible on the Jungfrau detector - surpressing via mirror alignment not successful

X-ray delivery

• 6 keV, ~2.7 mJ, stable delivery

Optical laser delivery

• ns laser for particle visualization

Achievements/Observations

• NKB focus optimized
• ns laser aligned with particle beam
• particle injector position optimized
• measured 3 samples: roughly 2 hours per each sample
• one sample was measured with and without He gas
• Julabo chiller (AGIPD) is still on target (-32 degree)

Issues

• Beam drift in vertical direction: Rz has to be corrected during the measurement and moved by 0.2 mm in total in whole day (~18 hours)

Started the day with vacuum & detector issues
real start of the experiments only at about 6 p.m. 
measurement of a selection of samples (urea, ludox) using the levitation device

issues: vacuum (behind AGIPD), motor (bend2 of the DES was in error - used for the beamstop)

X-ray delivery

• 6 keV, ~2.8 mJ, stable delivery

Optical laser delivery

• ns laser for particle visualization

Achievements/Observations

• NKB focus optimized
• particle injection tested with gold nanoparticles
• ns laser roughly aligned with particle beam
• Julabo chiller (AGIPD) is still on target (-32 degree)

Issues

• XTD2_ATT Arm4 (600um thick CVD) is damaged (most probably last week)

600um thick CVD diamond (XTD2 attenuator) seems damaged

Attachment 1: 600um thick CVD diamond (Arm 4) OUT

Attachment 2: 600um thick CVD diamond (Arm 4) IN

Issue with SA3 Gas attenuator (SA3_XTD10_GATT) - SOLVED

Dear all,

after the reported issue by SQS colleagues regarding the impossibility to inject Argon, and after a first remote evaluation, we (VAC) have entered XTD10 to assess the status and verify the most probable working hypothesis: a manual valve in the supply line was closed (otherwise as expected). Joshua and Benoit confirmed it and the showstopper is now gone. The system is back to normal and standard operation can be resumed in any moment. 

A small remark: as Argon (or any other gas different from Nitrogen) is not the default operation mode, it is important that if needed, there should be an explicit request during the preparation of the operation tables with XO. This would help to avoid this kind of situations. Unfortunately sending a short notice e-mail just before the next run is clearly not recommended.

With best regards.

Issue with SA3 Gas attenuator (SA3_XTD10_GATT)

9h06: SQS informs PRC that the Argon line in GATT is not reacting on pressure change commands, no GATT operation, which is required to reduce pulse energies for alignment. VAC-OCD is informed.

ZZ access is required to check hardware in the tunnel XTD10.
SA1 / SPB is working on other problems in their hutch (water leaks) and don't take beam.
SA3 / SQS will work with the optical laser.
SA2 / MID will not be affected: there is also an issue in the hutch and MID currently doesn't take beam into the hutch, and would anyhow only very shortly be affected during the moment of decoupling the beamline branches.

9h45: BKR decouples North Branch (SA1/SA3) to enable ZZ accesss for the VAC colleagues.

ZZ access of VAC colleagues.

10h12: The problem is solved. A manual intervention in the tunnel was indeed necessary. VAC colleagues are leaving the tunnel.

• Beam down SASE1: 9h43 until 10h45 (1 hour no beam), tuning done at 11h45, then 1.7mJ at 6keV single bunch.
• Beam down SASE3: 9h43 until 10h56 (1.25 hours no beam). Before intervention 4.2mJ average with 200 bunches, afterwards 2.5mJ at 400 eV / 3nm single bunch.

The xray beam drifted significantly on wednesday and thursday (18. and 19.) but then was not drifting on friday (20.), see attached trendline of the M2 actuator that kept the beam at fixed position on M3.

Today also seems that beam pointing is stable. But unclear what happened earlier...

- Pump-probe experiments are being conducted using PuMa and PP laser. 
- The user program is ongoing over the night.

Tomorrow, 
- Rotating the sample phi angle. The sample holder will be retracted from the MPC.
- Search the asymmetric film peak and conduct the PuMa and PP laser experiment.

X-ray delivery
8.951 keV, 1.6 mJ up to 16 pulses at 113 kHz

Achievements/Observations
More than 1h of beam sweeping with lysozyme crystals
Several runs of vitamin C beam sweeping data

Issues:
Several synchronization methods were tested for the mirrors but without improving it
 

- The seeding optimization is ongoing, which was not successful. Now we have a total of 170 uJ including SASE and seeding. 
- The option to switch to SASE is relatively not complex and can be done with the support of BKR without a seeding expert.  BKR expects to provide about (more than) 1 mJ. To be discussed with user later. 
- An investigation of the asymmetric film peak is ongoing to optimize the measurement conditions, such as diffraction angle, sample temperature dependence, and pump laser effect. Still, the PP laser effect on the diffraction peak on the asymmetric peak is unclear.  The higher sample temperature suppresses the diffraction intensity.  Unclear intensity changes over time have been observed. 
- The AGIPD moved closer to the sample to cover the more solid angle. 
- The MDL of the coupled motion of the hexapod and puma manipulator is not working reliably. 
- The delay time between the X-ray and the PP laser was cross-checked to ensure its correctness. No timing drift was confirmed. 
- Laser pump and X-ray probe experiment is being conducted at the vicinity of subtract peak. After optimizing the spatial overlap by scanning, the pump laser effect was clearly achieved. 
- The user program will be ongoing over the night. 

X-ray delivery
8.951 keV, 1.2 mJ up to 30pulses at 113 kHz

Achievements/Observations
Beam trajectory at 8.951 keV
IRDa slits left/right blades connected
Sweeped pulses could be observed on fluorescent paper in front of the Downstream screen
Mirror synchronisation parameters could be found
Jungfrau halves were closed and the downstream cone installed
Background was minimised using the IRDa slits

- The seeding optimization result: Total 450 uJ (Seeding of 150 uJ  + SASE of 300 uJ).  BKR will be able to start optimization on Saturday around noon if necessary. 
- The pump-probe (PP laser and PuMa pulse) experiment data on the substrate peak was collected. 
- Found the film peak on the AGIPD. Intensity optimization was not successful. We keep losing diffraction peak intensity over the measurement time and number of pulses. We assume the X-ray-induced heating can affect the diffraction intensity.
- Rotating Phi angle by moving the manipulator Z direction helped to bring the peak out of the detector gap. 

FXE received the beam and did not change accelerator settings.

Beam alignment to FXE was re-established using the new values for the old M1/M2 offset.

Monochromator aligned to the SPB energy setpoint.

THz source aligned to Xrays and several reference positions for Xray pointing taken. Further steps require THz radiation, which is not available at this point.

Xrays realigned back to SPB XTD9 screen.

On Shift: TS, FT, CK, AR, PS

X-ray delivery
8.951 keV, 1.6 mJ up to 200 pulses at 0.5 MHz (intesity drops off at end of train)

Achievements/Observations
Beam trajectory and focusing re-established at 8.951 keV
Temporary beamstop verified position for sweeping - confirmed by eric
Beam sweeping in synchronisation with pulse trains observed!
slit window assembly remounted and beam is going through to back of hutch in perparation for optimisation next shft

- DAQ was crashed after taking darks of AGIPD. It was solved by DOC and OCD.

- Laser could not switched from optical to RF lock. Solved by OCD (using doocs).
- Energy scan was attempted, which was not successful. 
- Seeding optimization was ongoing. It will continue tomorrow morning. Still there is intensity loss during the energy scan.
- We might see second (maybe higher) photon energy component on the beam. (https://mylog.connect.xfel.eu/#narrow/stream/201-MID_6877_UrsStaub/topic/.E2.9C.94.20Troubleshooting/near/72056)
- The beam was focused with CRL 2 arm 4 and 5. A precise beam size measurement would be useful. 
- The timing of XFEL and PP laser has been found from a frosted-YAG on the X-ray eye. T0 = 1374.94.
- The air gap between the MPC and DES are closed. 
- The first user sample is mounted and delivered in the PUMA setup.
- The spatial overlap of XFEL and PP laser has been found at the sample position with YAG crystal.
- The substrate peak (th = 20.7, tth = 41.4) was found on the fluorescent screen. 
- The SDL diamond detector was aligned on the beam, and now move it out.

 
Tomorrow
- Continuing of optimization of seeding and improving the energy scan.
- Cool down the sample and search the film peak on AGIPD.

X-ray delivery

8.951 keV, 1.6 mJ

Achievements/Observations

Beam trajectory and focusing established for 8.951 keV
HIREX inserted for energy reference for calibration tomorrow
Temporary beamstop verified position for direct beam.
Mirror tank inserted to beam path

X-ray delivery

• 12.8 keV, 1-20 pulses at 47 kHz, 500-700 uJ.
• Pulse energy constantly decaying since ~3:00.

Achievements/Observations

• Continuous SFX data collection since 00:10.

Issues

• Apparent mechanical issue with one motor. To be investigated before the restart of beam delivery.
• Beam horizontal drift still present, but not as pronounced as earlier this week.

Finally, the drift velocity of the pointing reduced approx a factor of 2 as compared to yesterday, see attached. Possibly it will still converge...