Starting shift with mirror motor calibration:

- beam is centered on FEL imager

- pblm in XTD9 is inserted

We removed both silicon solid attenuator and pblm

Starting shift with mirror motor calibration:

- found solid attenuator 0.5mm silicon inserted

- beam is centered on FEL imager

- pblm in XTD9 is inserted

We removed both silicon solid attenuator and pblm

we needed SASE1 to be set to 0 pulses briefly to check alignment in our experiment.

The FXE control hutch was empty. we could not reach either Chris nor Mykola by phone. The XFEL_StatusPublic shows that the FXE shutter is closed (we can also see the exp hutch door open from outside the control hutch).

Neither PRC nor BKR had any information about the FXE status.

We discussed with PRC and concluded that they are likely not using the beam, so in agreement with PRC we went ahead and got BKR setting SASE1 to 0 pulses at ~10:20. After few seconds, we got BKR setting SASE1 back to 30 pulses.

edit: PRC got in contact with FXE. Turns out they were (are) working in their ILH. we have a contact procedure for the next occasions now.

-Machine status

the cold compressor failure occurred at ~16.30hr today. And it will take around 35 hr to fix it. I will update via email (local contacts for experiments) and Operation Elog tomorrow with more details.

Naresh

We checked the XTD2 attenuators following the intervention from XRO (compar ewith elog:37, before the intervention).

The wavefront shows similar distortions with the 75 and 150 um as earlier, which is not too surprising since the cracks are vertical.

Attachments 1-5: Beam on SPB_XTD9_SCR with XTD2 attenuator CVDs

Attachments 6-7: Beam on FEL imager with XTD2 75 and 150 um CVDs

Yesterday two motors of the SASE2 seeding mono were damaged. The mono was exchanged in the afternoon and pumped down. Currently, an issue with the vertical cystal motion is being investigated.  The vacuum improved much faster than expected after this intervention, so the hope is that the tunnel can be searched soon and electrons could go through SASE2 already this afternoon. Watch for updates in the program for SASE2 in the DESY logbook under 'Schedule'.     

The intra-bunchtrain feedback (IBFB) was not active until today afternoon.
Although not strictly required or requested for the current week experiments,
it was decided to turn on this feedback, which should generally be active to
stabilize and improve the arrival time of the photon pulses along pulse trains.

In order to avoid complications during long data acquisitions, the PRC checked back with all ongoing experiments,
identified a suitable time slot, and the IBFB was activated without issues at aound 16h45.

V0 valve for SA2 closed as the pump P22090I at HED branch enters in wrong state. This closed nearby vacuum valves for HED branch and consequently V0. Vacuum levels at the section remained in 10^-9 all time.

Thanks to VAC-OCD Denis Finze we removed this pump signal from interlock to allow operation in SA2 at MID branch. Further investigation will follow on Friday.

Laser status:

After the laser issues listed in https://in.xfel.eu/elog/OPERATION-2024/99 the late shift was finally able to find a timing setting for the amplifier trigger that was beyond stable settings under usual conditions, but which allowed to continue taking data runs for the rest of the beamtime reliably. The users were already able to reveal indications of a pump-probe signal in their data.

The issue itself remains but didn't show up in form of unstabilities anymore. After the beamtime LAS took some effort to investigate and narrow down to either a faulty trigger going into the front-end amplifier or on the front-end amplifier itself. To the best of our knowledge this circumstance will need to involve EEE support or even a service from the manufacturer and cannot be solved solely by LAS. LAS ensured that the highest priority will be to deliver stable laser pulses for next week's beamtime as well.

FEL status:

we found the FEL poynting to be very stable troughout the last weeks beamtime (despite some short down-times), which allowed to reliably verify the spatial overlap.

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.

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).

Beam is back. Current status:

SASE1 (SPB/SFX)

• 2.72 mJ, 352 bunches/train, 6 keV

SASE2 (MID)

• 880 uJ, 1 bunch/train, 8 keV

SASE3 (SQS)

• 4.56 mJ, 1 bunch/train, 400 eV (3.1nm)

Desy Laser group has fixed the issue about the laser Synchronization.

https://ttfinfo.desy.de/XFELelog/show.jsp?dir=/2024/41/07.10_M&pos=2024-10-07T14:51:12

Naresh

PRC

wk41

Status

All beamlines in operation.
The attachment ATT#1 shows the beam delivery of this afternoon, with the pulse energies on the left and the number of bunches on the right.
SA2 was not affected, SA1 was essentially without beam from 13h45 to 16h15 (2.5h) and SA3 didn't get enough (386) pulses in about the same period.
Beam delivery to all experiments is ok since ~16h15, and SCS is just not taking more pulses for other (internal) reasons.

Beam delivery Status well after tuning finished (which went faster than anticipated).

it is not clear why, but the beam position on BIU2 has changed over time, even more since we checked last. it is off in both directions

we see the GATT aperture projection drifting, so it is a change in the beam transport, not in the source.

see the beam, cut by the DIAG1 slit, compared to the cross it should be centred to.

the motor encoders in the beamline have not changed since the beginning, when the beam was pointing correctly.

We asked the machine for two color mode in the morning. Tuning gave good results at first (1.6mJ second color, 100uJ first color), but as soon as any of the colors was switched off and on again the pulse energy dropped (~600uJ) and BKR had to retune to even get a fraction of the pulse energy back back. The same happened when changing the delay

X-ray beam is continuously drifting in the vertical direction (XTD9_XGM)
It affects our NKB focus and focused beam is also drifting continuously.

Today we have observed multiple large disturbances to beam stability. These can be characterised by large jumps in the horizontal beam position, which at its extreme amounts to a loss of beam from our behalf. M2 mirror feedbacks are able to return the beam to the initial position after ca. 10 minutes. Beam jumps have been approximately 1hr apart. We do not observe the beam on the XTD6 tunnel imager in this case, but do observe good lasing quality on the XGM.

The jumps keep repeating very frequently since yesterday afternoon. The overall drift of the beam seems to accalerate as well.