*Some more tuning of HXRSS and focus optimization in the morning.

*XPCS data taken in WAXS geometry on different glass samples.

*Migration of data is clogging up after about 10pm. DRC was contacted.

*Beam loss at 1am due to lost connection to TD5, MPS shut off beam in SA2.

Achievements

• Optimized THz EOS, managed to observe single shot EOS trace with good SNR
• Characterized chirp with different glass lengths
• Ran SiN spectral encoding in parallel

Issues

• No major issue

Achievements

• Observed first EOS of THz emitted from FEL-pumped STE on SiC and Si membranes
• Explored fluence dependence and damage limits
• Explored sample heating with pulse repetition rate
• Measure timing jitter of FEL with and without longitudinal feedbacks engaged

Problems

• DAQ was losing trains. Problem solved by DOC.

achievements

• optimized EOS signal from FEL-induced THz emission from STE on Sa of PAM
• reduced chirp to increase timing sensitivity to 9fs / pixel of PAM
• STE-based PAM measurements at fixed delay and delay scans. 
• after FEL down at 6am, continue with PAM measurements without BAM fast feedback mode (stopped after FEL back)

issues

• none

X-ray delivery

• 12.42 keV, 0.65 mJ/pulse, low pulse energy but mostly stable delivery

Optical laser delivery

• none

Achievements/Observations

• Unit photon flux increased by bending M2 bender more although incident pulse energy was about 0.65 mJ/pulse (10-20% lower then yesterday)
• Long data collection (4.5 hours) although we had rather low hit rate
• SideMic position and focus optimized in the end of the shift

Issues

• Even lower pulse energy (M2 bender helped a bit), any improvement will be helpful for Sun. night shift

* First half of the day was used to optimize seeding performance
* Cryo issues started at 6 pm; were resolved by 9:30pm
* After some tuning, we observed very nice seeding performance around midnight (ratio better than 1:1)
* Beam size seems too big; we measured 25x25 um w/ knife edge scans and CRL2 lenses 3,5,6
* Mounted the x-ray again, and left the chamber pumping overnight
* Morning crew, please double-check the beam size tomorrow

achievements

• checked coarse timing between FEL and PPL at XOX. It had shifted significantly
• determined that light coming out of sapphire from FEL was not heating but fluorescence
• observed for the first time THz emission from STE from FEL pump on sapphire substrate and mesured with single shot EOS

issues

• FEL down for 3h

The Cryo team solved the problems, beam is back.
Downtime from 17h59 until 21h03.

18h05 : RC informs:

Machine is down, because Cryo-OK was lost.
Apparently it is a turbine but not the cold compressors.

It is thus not yet known how long the downtime will last.
More info will come within the next hour.

MID and FXE were informed by PRC, SCS could not be reached yet.

X-ray delivery

• 12.42 keV, 0.8 mJ/pulse, stable delivery

Optical laser delivery

• none

Achievements/Observations

• BG optimized (1-2 photons)
• Realignment of offset mirrors (M1 & M2), cube, straw, sidemic
• Jungfrau4M timing checked and optimized for single memory cell operation
• About 2 hours data collection

Issues

• Low pulse energy (Tomorrow, BKR and we should optimize the pulse energy)
• Extremely slow data calibration (it took more than 1 hour for 10 minutes run)

* Data collection of vycor and glass samples in SAXS geometry until 9am

* Successful intervention on SA2_XTD1_ATT arm 6 by the vacuum group, see elog entry 237 by Raoul and Bianca . Thanks!

* Simultaneous CoC in the MID hutch to WAXS geometry.

* Beam back for tuning around 4:30pm, HXRSS tuning still ongoing

achievements

• try pumping STE membrane with FEL and detect THz emission with single shot EOS. No success.
• tried cross-polarization for a short time, no success either.
• reduced the PPL chirp to record single shot transient reflectivity data versus BAM for the night.

issues

• FEL on STE on sapphire show strong glowing so it's probably not the right regime to get THz
• we don't have a self referencing scheme to observe THz emission from PPL pump

Dear all,

After the incidences reported yesterday and the diagnostic remotely done (where we could narrow down the root cause to the edge-welded below at the Linear stage of the arm Nr. 6 - 2.4 mm CVD diamond], we confirmed this as a fact during the schedule access today. Here is a succint summary of what happened.

1. Although planned for 9:00, we could only enter the tunnel past 10:15 due to some issues for the accurate release of the XTD1 tunnel interlock, in such way that the use of the XHE2 elevator could be used.
2. The first action was confirming the first hypothesis. The result of a direct He-leak test shown a leak rate up to 5*10-6 mbar*l/s, which was consistent with the observation from yesterday. No other leak was found.
3. After securing the vacuum integrity of the lateral sections, venting the long sector took some time.
4. We also had some issues with the vacuum connections of the affected actuator, but eventually it could be eventually removed.
5. A first evaluation of the 2.4 mm CVD diamond, no major damage is evident and the chances of reusing are high (at least at first sight).
6. Also, the repair of the leaky part (or better said, its eventual replacement) seems feasible, and would only depend on finding a similar bellow equipment. XRO is working already on this.
7. The vacuum system could be recover relatively fast to an extent where a general leak test could be performed again. No further leaks were found.
8. After the removal of the arm 6, and the reconfiguration of the pneumatic system, we tested several time (in air and in vacuum conditions) that not having the arm 6 wouldn´t block the use of the solid attenuator. Also XRO check/is checking all the possible implications for the "normal" operation of the beamline.
9. At 13:30 we communicated with BKR and later with the PRC to provide feedback on the progress.
10. At 14:15 we confirmed that we were leaving already the tunnel, so the tunnel search could be triggered.
11. Around 14:30, the SA2 vacuum OK signal was released and confirmed by BKR operators.
12. In conclusion, the time envelope  of effective work (4h) was achieved.

At this moment, the sector vacuum level is recovering positively and the average pressure is in the 5*10-8 mbar after 2,5 hours of pumping the the ion pumps, which is a good indication of the overall success.

With best regards,

R. Villanueva & B. Dickert.

Repair of SA2_XTD1_ATT

Status 12h30:
The current MID users took beam until 9am, only then the machine could start preparing for the tunnel access e.g. by decoupling the South branch, powering down magnets and taking XTD1 out of the interlock. The VAC team was ready to go into the tunnel for the repair in XTD1 already since 8am.
Unfortunately, the tunnel access of the VAC team got delayed beyond 9am by one more hour to 10am because the DACHS terminal at ground level of XS2 was found defective, and releasing the tunnel interlock took substantial time.
DESY experts went onsite and informed that a proper repair of the DACHS terminal can only happen next monday.
Only with a workaround, finally the VAC team was able to use the elevator to bring the required large venting and pumping equipment down to the tunnel level.
The vacuum works are ongoing with highest priority.

Status 14h20 :
VAC has finished the intervention, informed BKR and PRC, and is leaving the tunnel. Tunnel search team can start.

Status 15h00:
Tunnel search almost finished (also found some technical obstacles), Seeding experts are informed and ready to start their work.

Staff: DZ, AR, MK

X-ray delivery

• 12.42 keV 169 pulses for alignment 16 pulses for data collection. stable delivery excluding the extended interuption

Optical laser delivery

• none

Achievements/Observations

• Continuation of lysozyme experiment with parameters from yesterday
• data collection time limited by machine downtime, alignment optimisaiton and cleaning of the sample buildup around the interaciton region.

*Vacuum issues: There seems to be a leak in the arm nr. 6 (2.4mm CVD Diamond). This has escalated to trip several times the vacuum sector interlock. VAC will do an intervention to XTD1 with broken interlock tomorrow morning starting 9am to remove arm 6 permanently and putting a blind flange instead. 
*We can measure for today with the 2.4mm CVD Diamond inserted into the beam.
*Measurements on Vycor and glass samples with different attenuation at and repetition rate (2.2 and 4.5 MHz)
*A25 trip at 1:14, after some intervention we get the beam back at 2:12

SA2_XTD1_ATT solid attenuator vacuum issue

Info from VAC (Raul Villanueva) 12h30:

It seems to be a leak in the arm nr. 6 (2.4mm CVD Diamond). This has escalated to trip several times the vacuum sector interlock.
On top of that, we also discover an issue with the configuration of a ion pump controller that have required the intervention of DOC / EEE. 

If the arm 6 is kept closed (2.4 mm CVD  is inserted), the leak rate seems to be small enough to allow operation (average sector pressure in the low 10-7 mbar). Otherwise it will blow consistently the interlock. (I repeat here: DO NOT MOVE THE 2.4 MM CVD!!!) See attachment #1. Most probably the leak would be in the custom-made bellow of that particular actuator. XRO just confirmed that there is no spares available.

Info by MID (12h30):
For today, MID can operate with the 2.4mm diamond inserted without impact to their experiment. However, tomorrow morning there will be a new user and experimental setup, which will require full transmission throughout the weekend, therefore the 2.4mm diamond attenuator must be removed friday. The change in experimental setup means that MID will work in the hutch at 10am for several hours and won't take beam anyhow.

Discussion of PRC+RC+XO+VAC+MID (15h30), with agreement to the following actions:

a) VAC prepares an intervention to XTD1 with broken interlock tomorrow morning startin 9am to remove arm 6 permanently and putting a blind flange instead. This intervention is estimated to start 9am and last for 4 to 5 hours. VAC will inform BKR if the work can be completed quicker.

b) Next week (last operation week in this run) therefore the Solid attenuator arm 6 won't be available. HED confirmed to PRC that it will be acceptable for their experiment since they plan to use full transmission in XTD2 and use their own attenuators in the HED hutch to attenuate the beam. XPD confirms that the XTD2 attenuators are not required for HIREX operation since HIREX contains its own attenuators between the bent crystal and the detector.

c) BKR/RC will organize the required tunnel search for the friday afternoon, and subsequently the HXRSS team will start optimization.

d) X-Ray Optics has already initiated the contact with the ATT device supplier to get replacement parts that will allow to recover full functionality during the upcoming (short) summer maintenance week.

Addition to previous issue:

Last incident (of overall 4), we had 0 bunches, moved in XTD1 ATT 0.6 and 1.2 mm CVD diamond in and 2.4mm CVD out. However, vacuum started to become bad already two days ago.

Update from vacuum OCD: Seems to be related to one leaky below of 2.4 mm CVD arm. Operational consequences are discussed right now.

SASE2 vacuum incident

7h10 : MID informs PRC about a vacuum incident in the SASE2 tunnel which tripped the beam. Instructed to contact directly VAC-OCD

8h26 : VAC-OCD informs that investigation is ongoing, but beam can be delivered. This kind of trip usually occured rarely
           and usually can be reset by VAC. Apparently the source of the issue is at the XTD1 solid attenuators.

8h36 : MID confirms to PRC that already 3 trips occcured but the experiment so far can continue. Beam delivery continues.

10h11 : VAC-OCD informs that now there is a bigger more wide-spread issue with the XTD1 vacuum system
           and beam operation is stopped for at least 1 hour. VAC group and DOC are working on the issue.

11h : It turns out that the vacuum bellows of the 2.4mm diamond attenuator in SA2_XTD1_ATT has a leak, which is worse and
         not acceptable in terms of vaccuum in the extracted state (bellows elongated) but less severe in the inserted state (bellows compressed).

12h33 : info by VAC: issue is temporarily solved by blocking the 2.4mm diamond arm in the IN position. Must clarify today how to proceed further.
          The vacuum issue thus is temporarily solved, beam permission is back,

12h38 : Beam coming back to MID. MID can work today with this ATT always inserted, but not for the weekend.

achievements

• setup spectral encoding of the transient reflectivity in FFT
• determine coarse timing in the XOX
• fixed BOZ_Z motion and DSSC silicon oil pressure reading

problems

• nothing major