Ramp down activities completed by XPD. References:

• SASE1
  • https://in.xfel.eu/elog/SASE1+technical+commissioning/2204
  • https://in.xfel.eu/elog/SASE1+technical+commissioning/2205
  • https://in.xfel.eu/elog/SASE1+technical+commissioning/2206
• SASE2
  • https://in.xfel.eu/elog/SASE2+technical+commissioning/1206
  • ...until...
  • https://in.xfel.eu/elog/SASE2+technical+commissioning/1209
• SASE3
  • https://in.xfel.eu/elog/SASE3+technical+commissioning/2220
  • https://in.xfel.eu/elog/SASE3+technical+commissioning/2221

The XFEL photon beam was switched off as planned at 19h00 sharp.

Machine is preparing for opening the photon tunnels tomorrow morning and to start the winter maintenance period.

22h55:
HED informs that they have issues with the HED pulse picker in XTD6. It affects the ongoing experiment, but not to an extent that they cannot continue the beamtime.
It will be more an issue for the next beamtime starting this weekend, therefore they are looking into solutions, working together with DOC and EEE.
They might need a ZZ access to XTD6 to check the pulse picker mechanics outside vacuum.

22 Mar 2023, 23:30 Handover from late shift

Tasks for the night:

• source point measurement
• Sample alignment
• timing

23 Mar 2023, 00:39 Source point measurement with CRL1#2,6  Att1,2,3 Meansurements taken on YAG and attenuated beam

• source point: -13.9m
• divergence  : 3.38urad

23 Mar 2023, 02:39 birect BS out, specular in (cf. confluence); CRL4b out, 4a in (at rough focus ? (pos~70mm)); OPT ATT = 1.68e-7;
moved the sample upstream along the target surface (along 359.5deg) to see the downstream edge, brougth ILM and flatfield to fine tune downstream edge to TCC, see sharp edge on ILM and half FEL cut on JF (see attachment5), with IC1 light on two edges (front and backside) are destingushable; target saved to slot slot 26

23 Mar 2023, 03:06 moving the sample edge in hight; on the ILM we see it stays in the focal plane but moves sideways consistently with the JF were the beam gets less and less cut; tried to adjust the angle HEX V (should be around the axis along the FSSS frame) but this seems to be too tricky and time consuming because of the missing pivot point close to TCC. for this reason we can only go in small steps to not bump anything and losing the FOV off the ILM; since every sample will slightly different mounted a better approach might be to compensate the lateral shift in the imaging plane of the ILM by moving along this plane (135deg); for 23mm hight travel ~155um shift along 135deg is needed (after that we had to refocus the target edge by ~20um)

23 Mar 2023, 04:05 we decided now to switch to spatial overlap and timing. The FSI seems to be out of focus. Thats why we go back to a pin and center it to the current FEL beam position and ILM and will adjust the FSI if neccessary

• unfortunately nobody corrected the relay imaging path and/or the filter/beam block stage for the ILM !!
• fine tuned the wire alignment - image quality is very bad on FSI. Not really great on the ILM ( I guess we are clipping in the objective and relay lenses  (Att6 and 7). Seeing now the relative sharp image in the pin, it raises the question why the samples on the image (Att5) on the FSI are blurry.
• could not find t0 within a few ps; thus removed CRL4a, changed from JF (detb_x=820) to OP (detb_x=1151.1), 100% FEL transmission and from OCX to RF lock found back t0 in IC1 (~25ps off from yesterday)
• rechecked PAM spatial for all YAGs, with YAG emission on the camera we went to YAG 100um cross and refocus the objective
• went back to optical lock

15:15  SCS called and reported an issue with one of the motors of the SCS exit slit. DOC already looked at the problem and could not make the motor move. XRO (Maurizio) is now informed and looks at the problem

17:10 ZZ access to XTD by Maurzio and Mikako

18:00 ZZ finished. Unfortunatly the motor is completely blocked, even with cables disconnected one cannot move it. 

The longitudinal feedback on SA1/3 was swicthed off by mistake over night. When it will be switched on, the beam may wiggle a bit an SA1+SA3 for short. 

We agreed with SCS and FXE that this will be done today at 11:30 

In order to optimise the performance of SASE2 self seeding, a stronger compression setting is required. 

The RC proposed to increase the time window between SASE2 and SASE1/3 to avoid performance degradation and cross talk effects on SASE1/3. 

I discussed with SCS and FXE instruments and there seems to be nothing against moving the time trigger by 30 micro seconds later, as proposed by BKR. 

The agreed bunch train lengths can be still achieved with the new setting. The change will be implemented now (Tue 14:45)

SCS could only use two pulses, because the SXP imager was still in the beam and SXP shutter open. 

I removed the SXP imager, so SCS can now get the full beam. The SXP shutter is still open and SXP instrument contacted via email to find out, if the shutter is intentionally open. 

21:13: SXP confirmed that they will close the shutter tomorrow. The imager was just forgotten in the beam. 

After the 12 hour cryo failure last night, it was decided to exchange a faulty window with some reduced transmission at the injector laser today (see email by Andreas to xo-info yesterday). 

This was sucessful and the injector tunnel was closed today 16:40 and restart of the gun is ongoing. Tomorrow ramp up and SASE tuning.

The hope is that the large jitter and the poor SASE performance of last week can be now improved.  Beam delivery to instrument is expected on Thursday. 

As discussed, there will be a beam interuption form 14:45 until probably 15:45 related to jitter studies at A1 that the BKR would like to try out. 

Harald

Good news: The 'jitter'-tests was sucessful and BKR could identify the jitter source related to a wrong software setting around the AH1 module of injector.

This was now fixed and the jitter has disappeared  . It is likely that the tuning was compromised by this setting from the beginning of this run (July11).

On Monday morning, a fresh tuning round will be started with hopefully improved SASE performance. Until then photon delivery with what we have.  

The hutch search of SASE3, SXP became defective around 5am. 

DESY MPS group replaced a defective warning light unit and now it seems ok.

End of Euler shift: all 3 SASE2 mirrors are now working with the Euler MDL.

We left the beamline aligned to HED, with M1,M2 on Pt for upcoming HED experiment at 18 keV.

Pre-absorber closed, CRL1 out, Solid attenuater with some diamonds.

achievements:

• change the optical laser to 2 um
• found focus of 2 um beam
• found saptial overlap
• course timing was checked
• looking for fine timing using SiN

problems:

• fine timing signal not seen yet

achievements:

• calibration of exit slits
• measurement of Cu L3 edge
• moved hRIXS to nominal settings for Cu L3 edge

problems:

• hRIXS motors could not be moved remotely, the problem was finally understood: GTZ had been moved manually into an interlock condition, going then to remote operation bring the motors to error state, it is then impossible to go out of error state from remote operation if there is also an interlocked state. In this case, the solution is to move the motor away from interlock state manually and then move to remote operation.
• vavle with filters in front of grating chamber cannot be moved: problem unsolved, please Martin have a look at it.
• DA online analysis tool for XAS was not working, DAC contacted Oleksey from DA and problem was fixed

plan:

• optimize beam dimension for hRIXS
• find rixs signal and optimize resolution

achievements:

• FEL beam realignment because pointing was off since we had 0 pulses during the night
• coarse timing was found
• knife edge scans of FEL to achieve twice the PPL beam size

problems:

• several machine interruptions, partially due to corss-talk with sa2 and 4.5 MHz oparation
• gate valve before KB XOX/GV3 goes into interlock and then stays closed, probably due to pressure spikes

achievements:

• beam transport with the second half of undulators closed
• measured pulse energy in SCS hutch and verified that the transmission of the beamline with hr grating is as previously reported
• knife edge scans along vertical direction to find focus (<=11 um) and horizontal direction to have 175 um
• half clip scans to find center of rotation
• aligned Cu and Ni ML (theta offset) to find signal of Cu and Ni at hrixs
• delivered the beam at the hrixs ccd camera

problems:

• all the undulator cells were closed instead of only the second half of the undulators

plan:

• optimize energy resolution at hrixs at Ni L edge (priority)

achievements:

• changed the LEPM to optimize resolution
• found 140 meV

problems:

• were not able to recover settings found because it is difficult to reproduce LEPM positions

plan:

• try to improve resolution

Achievements

• Beam transport
• Coarse and fine timing
• XAS on Co
• Aligned HSLIT, pinhole, camera beamstop
• Characterize FEL beam size and position on curved grating
• PPL Power measurement
• Fluence scan on sample of optical laser and FEL to determine good conditions
• Prepared for night shift time-resolved measurements

Problems

• No major issue

achievements:

1. found new M2 bender position for focusing using blank
2. tried to use unfocused beam for ESLITS calibration, but could not see it at SCSPopin, only at M5 Popin
3. we moved the XRD chamber laterally, closer to hRIXS, to be able to cut the beam using the sample at grazing incidence
4. seen FEL on antenna, measured FEL spectrum at navitar

problems:

• general slowness of SA3 motors whenever the whatchdogs were active, switching them off seems at least to mitigate (solve) the problem
• navitar camera in unknown state
• scs daq control in unknown state (problem caused by FADC not instantiated)
• SCS_XTD10_TPI/CAM/SHUTTER was in the UNKNOWN state: the camera cannot be pinged, probably it is disconnected. WE NEED TO FOLLOW UP WITH THIS
• HSLITS blades were in error and could not be moved, Leandro fixed this problem, the issue was at the PLC level and related to the encoder
• ESLITS imager and SCS POPin could not be moved, DOC (Dave) fixed this problem
• we could not propagate the unfocused beam to the SCS Popin, only up to M5 popin

plan:

• look for signal at the hRXIS
• optimize resolution by changing LEPM angle
• measure XAS using MCP
• look for signal at APD after moving the APD on the side of the sample that is not blocked by the L shaped knife edge

achievements:

• inserted the magnet and measured delay scan at the maximum magnetic field with opposite directions
• data analysis showed that runs measured during the afternoon/evening led to sample degradation (the sample shows a dark spot, change in the scattering signal is also cearly visible)
• corrected spatial overlap
• moved to gresh spot and did delay scan at lower OL fluence (Tr = 35% instead of 70%)

problems:

• shortly before 23:00 the optical laser synchronization was lost for a bit more than 2 hours, then it came back shortly after 1 am at that time the PP laser phase shifter when optically lock moved from 1018 to 229.8 apparently on its own, and it was realized few hours later. We moved it back to the original value, but this was not sufficient, we had to move by several ns and we were not able to move where we wanted, Laser OCD was called a7 7:35.