intense data taking on various samples

2 main issues:

- data collection using the optimize macro is too fast for the system and calibration and the data transfer from SDD to HDD is slower than collecting new data

- FSSS axis scannerY gives frequent errors since this night which is stopping the macro - check by morning shift & DOC is required

Staff: KK, RB, TG, AS, CK

X-ray delivery

• 9.3 keV, 1-120 pulses,

Optical laser delivery

• No Optical Laser

Achievements/Observations

• EHC Shimadzu timing and focussing
• Two-Plane Measurements Tested
• SA1, NKB and EHC Shimadzu flatfields recorded
• Y - Double Slit diffraction pattern recorded on EHC Shimadzu

Issues

• Bassler cameras misbehaving

Instrument status

• AGIPD HV off.
• AGIPD gate valve closed and pinned.
• Attenuators set to thickest diamond.
• Vacuum valves closed.
• EHC and NKB Shimadzus focussed and timed
• Sample in out-of-beam position

To do for next shift

• EHC Shimadzu Measurement of Y-Double Slit Pattern - both shimadzus currently focussed w/ respect to YAG screens and EHC and have correct timing.
• I0 Monitor comissioning.

- Tunnel + experimental hutch alignment (Mirrors, CRL1 and CRL2)

- Aligned main devices: Optics Peter, x-ray eye, EPIX and Zyla and pin holes.

- Tried some alignment of the NFL (1D) lenses with pin hole and not pre focussed beam. We found a lot of scattering from pinholes which dominates the signal on our x-ray eye. This task has to be redone with CRL2.

- We aligned magnetic beamstop

- We moved sample stage inside the beam (do not move optics peter!)

- We insert CRL 2 and took some data with EPIX and Vycor. We checked the beamprofile with x-ray eye it looks elongated.

Problems:

- Timescan is not working

- lot of scattering from pinholes when using large beam on NFL

We were set-up for 5.7 keV photon energy in SASE1. We made a test with BKR to change this energy to 9.3 keV. This had an effect on our two-color setup:

The first color pulse energy increased. See att 1. Green is the reference at 5.7 keV, blue is at 9.3 keV.

Att 2 shows the XGM history: pulse energy went up to 200 uJ in SQS XGMD during the change.

the users are unhappy about the increase of pulse energy in the pump pulse, because the ratio of pump versus probe is optimized with the setting where SASE1 operates at 5.7 keV.

we plan to record continuous delay scans (about 1 day for each scan) for the rest of the week, and pump-probe settings should be constant over time.

After realignement of M1 and M2 we could solve the problem of the elogated beamprofile. Different lens setting were prealignd for the use in combination with the NFL.

We took data for several 1D diamond lenses together with a Vycor sample to extract the beamsize from the specles.

We tested pulse on demand scans with scantool and confirmed that there is only one shot per scan point. This was used to print the footprint in a LIf crystal.

We took caustic scans for 1D diamond lenses using a wire and using specles to extract the beamsize.

- Measured the speckle patterns using EPIX detector to estimate the beamsize focused down by 1D lens (Row 13).

- Heat load test to NFL #18 with 50 bunches.

- Measured the speckle patterns with 2D focusing lens to estimate the beamsize. wire edge scan?

- Local optics hexapod had some issue in moving while alignment. DOC helped us to solve it.

-Sample hexapod is not working, need to be checked in the morning.

• HXRSS delivery, 600 - 700 uJ, 1 bunch, 8.991 keV. Pedestal visibly in HIREX, not checked with MID spectrometer yet.
• beamline aligned and beam brought to popin imager
• struggle with jet pumping, to be continued
• beam brought into experimental hutch, first rough alignment of reference samples and cameras
• Epix flight path leaked and window re-glued

Stable HXRSS delivery with >800 uJ, 1 bunch, 8.99 keV.

Re- Alignment of X-ray beam performed.

-Beam position defined for sample interaction in SAM CAM1. Do not touch SAM CAM1

-X-ray beam (unfocused and focused) is now going through LIC & 45 deg mirror. Updated M2 feedback setpoint.

-CRL2 has been aligned to the new position.

-Lower branch SDL aligned. Not on Sample interaction point.

-LIC mirty moved out -63 mm (in at 6 mm)

Status now:

We moved lower branch out. CRL2 left in.

We have left the direct beam (no branch) on the X-ray eye and inline microscope.

We have left some diamond in the OPt Hutch Att for running  feedback and HIREX

To do:

- Bring both branches to the sample interaction point in SAM CAM1.

- Aligment upper branch

- Spatial overlap laser and X-ray

- temporal overlap with diode (from laser and lower branch?)

- Beamsize analysis of both branches

• stable HXRSS delivery at 8.99 keV, 1 bunch. XGM intensity during the day decreased from 750 uJ to 600 uJ.
• Vacuum in sample chamber stabilized with cold trap and full beam path opened to AGIPD and endstation
• Again problems with smaract stages in DES, but imager in a good position to continue.
• First scattering data recored from water jet. Unknown, bimodal intensity distribution
• Focus characterization of SDL lower branch with knife edge, X-ray eye and SAXS speckle data. Larger (>10 um) as compared to direct beam with same focussing setup.
• Clear influence of splitter insertion on beamsize observed. Beam is smaller without splitter crystal.
• Current status: Alignment of upper branch unfinished, X-ray eye inserted, sample chamber vented

For the next shift:

• Finsish alignment of upper branch
• Characterize both beams in size with Xray eye. Try if slightly different lense combinations or M2 bender settings improve the situation.
• Overlap both beam on the sample
• Possibly insert upstream pinhole just in front of jet to clean up and ensure overlap
• Take data, enjoy

• upper and lower branch of SDL aligned
  • beamsizes and angular mismatch characterized
• vacuum leak of flight path fixed
• side view microscope re-aligned
• problems with replaced MPC diamond detector. issue with in-vacuum cabeling suspected
• misconfigured timing of AGIPD fixed
• splitting ratio of SDL detuned while HXRSS intensity decreased significantly. Possibly correlated.

With the current HXRSS intensity and focussing, we have insufficient conditions to take data for the experiment. We decide to vent the sample chamber and try to fix the malfunctioning diamond detector instead of taking data over night. HXRSS should be improved tomorrow morning and the SDL possibly realigned afterwards.

After setting timing witht he diode, we look at the PAM spectrometer and scan the laser timing a bit.  We found a clear change in the spectrum - at >t0, the spectrum was very attenuated and at t<t0, the spectrum was larger.  This persisted for many 10s of ps (very unexpected behaviour).

In attachment are the LA3 timing scene, the SQS delay stage, the BAM, and the spectrometer signal from Metro at t0. att. 1 - 4.  The averaged ratio shows the cut the best.  Unfortunately we do not have references on that, so we will ask Sergey or Bjoern to do it tomorrow.

We found that the intra-train timing feedbacks of the accelerator are off. We ask BKR to fix it, which took a while. Aparently, we have to communicate the need of the timing feedbacks (and BAM) more clearly.

Standard deviation along train is now 18 fs with feedbacks on, see att 5. Was around 100 fs without the feedback!

We take a run and manually move the PAM delay stage so we have a timing calibration for PAM.

run 32: Rubbish because DA03 got stuck.
run 33: scanning PAM delay stage manually. device: SQS_AQS_LAS/MOTOR/WAVEPL_LMD2_1030. Typically taking 5um steps.

Went to the PAM delay stage position shown in att. 6, and had the PAM signal shown in att. 7

Attachment 1: Beam in SPB hutch with Si500

Attachment 2: Beam without Si500

Achieved

1. Brought the X-ray to the end of the beamline. 
2. Aligned the goneometer with a pin. 
3. Found the timing of AGIPD at the detector distance of about 3.4 m from the sample.
4. Found the timing of Jungfrau detector in burst mode.
5. Measured the X-ray beam size at the sample position with the X-ray eye for two combinations of CRL 2 (e.g., CRL2 3,4,7 : 14 um x 19 um, CRL2 3,7: 28 um x 34 um ).
6. Collected some x-ray scattering data from the thin film HfN on the Sapphire substrate.
7. Bragg peak analysis via Extraform is running with 16 X-ray pulses per train.
8. The HIREX gave the energy bandwidth of the self-seeding spectrum about 0.71 pixels. 

Issues

1. The rotation motor of MID spectrometer is frequently stuck. The ticket number is #151832
2. The data calibration pipeline of AGIPD sometimes goes into an error state. It could be related to the XGM data. The ticket number is #151837
3. XTD1 attenuator controller and the watchdog device didn’t behave correctly and died in a few minutes. After that, it removed the attenuator itself without any notice. It could have damaged anything very seriously. 
4. The optical pump laser has had some issues with hardware failure (piezo mirror) since 11:25 today.  The laser group fixed the issues, but the system requires some time to be stabilized until tomorrow morning. It might need more time based on the measurement result tomorrow morning. 

Achieved

1. Brought the 800 nm of optical pump laser to the hutch after the intervention. 
2. Found the rough spatial and temporal overlap between the X-ray and pump laser with MID X-ray eye. 
3. Found the sufficient photo-induced effect on the user sample (HfN) with one unpumped X-ray pulse and 12 pumped X-ray pulses. 
4. Installed the lambda/2 wave plate and controlled the optical laser polarisation at the sample surface.
5. Bragg peak analysis via Extrafoam provides an intuitive and prompt result during the measurement, which is very useful for deciding the following procedure of measurement. 
6. A measurement scan for 3D reciprocal mapping has been collected using the Karabacon macro for varying the time delays and omega angles.

Issues

1. The Jungfrau detector dropped approximately 60% of trains in the saved data.

Report

1. The optical pump laser was not able to be brought to the first X-ray pulse. The first unpumped X-ray pulse data is used as a reference, which is useful to this experiment. 

Shift Summary

1. Collected optical laser-induced dynamics in HfN and STO/SRO samples.
2. Jungfrau detector transferred data without data dropping issue. 

• Beam came back quickly after cryo-incident with ok seeding performance (not very stable).
• Finish 3381-Pudell beamtime with SRO/STO samples at time delays and laser fluences.
• Decided not to scan the HXRSS energy but stay at current position
• Mount samples for 3331-Robinson experiment and search for Bragg reflections, we could find the specular reflection for the two largest samples but not the magnetostrictive one.
• The specular reflection for the 8x8um sample is currently aligned.

Problems:

• AGIPD darks could not be pushed into the calibration pipeline, the problem was fixed quickly by DOC and OCD

we lost spatial overlap on several instances.

It seems that this happens when SASE2 changes number of pulses.

when we have SASE2 changing number of pulses, spatial overlap is lost and this goes with a change in the position read by the xgm in the order of ~20um (e.g. attachment 1).

Yet, the XGM position reading is not really representative of the effective pointing changes: a drift of that order, occurring when there is no change in SASE2, does *NOT* correspond to a loss in the overlap (seen in the N2 signal in our experiment).

in summary: some evidence suggests that SASE2 number of pulses changing affects our FEL beam pointing. Yet, we don't have a diagnostics allowing us to quantify this.

BKR changed the beam energy from 15 keV to 12.4 keV

Energy 12.4 keV

Repeatation rate 1.1 MHz

Average pulse energy 1.8 mJ

Dear all,

the closing report on this issue can be found in the following Alfresco link:

https://docs.xfel.eu/share/s/GzxORQOGToe_tiug7LIHhQ 

Regards,

R.