15:30 We have a break due to an issue at UNILAC (quadrupole failed). Also radiation safety interlock was triggered at the fragment separator. This also pushed a faradaycup into the ESR (GE01DC3VP).
Just before the issue during the last bunching, the peak was misaligned to the marker in the Schottky. The marker was sitting on the right flank. So the electron-cooled 229Th did not match with the bunching frequency anymore. We are preparing to adjust the cooler voltage to fix this. For some reason the frequency recovered and is back to its original position. However, our accumulations do not seem to work as well as before, we stagnate much earlier and at a much lower level.

15:50 Beam is back, Carsten is still investigating the drop in intensity we saw before the UNILAC failure.

17:15 TE slits were on -8 and +8, opening to -11 and +11, no change to acquisition pattern, something is still wrong

18:00 We were locked out by HHT people for 30+ mins

18:27 We had to call in ESR support

[TABLE border="1"]
Time | Part. Det. Int | SIS-intensity| accumulations in ESR |  cooler-HV PTB K250 |  cooler-HV PTB red | cooler-HV orange | LMD-DAQ1 Files | LMD-DAQ2 Files | scan range(nm) | number of positions | dwell time (laser shots) | n loops | checked laser position | mesytec rate ok | comments
|-
14:24 | 15800 | 2.74 e9 | 30 | 104524 | 104527 | 104528 | 196 | 224 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
|Carsten optimizing beam at HKR with ESR colleagues
|-
14:24 | 6800 | 1.16 e9 | 30 | 104524 | 104527 | 104528 | 197 | 225 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
|Carsten is back in measurement hut
|-
16:30 | 1100 | 1.1 e9 | 40 | 104524 | 104527 | 104528 | 198 | 226 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
| Searching for reason for small particle number
|-
17:00 | 1200 | 0.5 e9 | 30 | 104524 | 104527 | 104528 | 199 | 227 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
| 
|-
 19:57 | 7800 |  1e9 | 30 | 104524 | 104527 | 104528 | 200 | 228 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
| Restarting some things at ESR
|-
 20:16 | 6800 |  1.5e9 | 30 | 104524 | 104527 | 104528 | 201 | 229 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
| Restarting some things at ESR
|-
 20:41 | 7200 | 1.5e9 | 30 | 104524 | 104527 | 104528 | 202 | 230 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
| Restarting some things at ESR
|-
 21:28 | 6000 | 2.65e9 | 30 | 104524 | 104527 | 104528 | 203 | 231 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
|
|-
 21:47 | 6600 | 2.7e9 | 30 | 104524 | 104527 | 104528 | 204 | 232 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | 
|
|-
 22:08 | 17000 | 2.5e9 | 30 | 104524 | 104527 | 104528 | 205 | 233 | 551.91 - 549.41 | 501 | 15 | 1 | yes | yes | TE slits -7 +7
|
|-
[/TABLE] 

We cross-checked the timing. Laser pulse is detected at bins 136 (PD-North) and 171 (PD-south), respectively. Therefore, the laser puls is in the electron cooler at 153.5. The revolution period corresponds to 3e8Hz / 1.54315MHz = 194. 
The ion bunch must travel 2.5m more than the half of the circumference (108.3m). Taking this into account, the ion bunch must be detected (0.5 + 2.5 / 108.3) * 194 = 101.5 bins later (meaning less) than 153.5.
Finally, we are happy that the timing is still perfect, since the ion bunch arrives at 52. 

We checked the timing (before the start of the measurement cycle documented below).
Timing and measurement window are attached.

current settings of PMT voltages and thresholds at the CAEN CFD:

PMT South   [HV ch2: 2700V]  [CFD ch0: 8]

PMT Middle  [HV ch1: 2850V]  [CFD ch1: 8]

PMT Nord    [HV ch3: 2850V]  [CFD ch2: 9]

Cobra's FCU was recalibrated. Table saved as FCU_547-554_RS_2024-06-25.fcu.

In the SetParameters.C file is a parameter called fPar->piPhaseOffset. It was shifted from 100 to 50 in order to see ion bunches in the pmt signal and laser pulses in the photodiode signal during the same revolution in the TDC spectrum. Note that this parameter must be taken 
into account when setting the window conditions of the arrival time in the SetConditions.C file. 

We tested the PMTs again, this time with an UV LED that is mounted at a window close to the XUV detector.
PMT south showed a very clear increase in count rate from about 1 to 50 Hz.
PMT mid also showed a small increase by a few Hz.
For PMT north there was no great change between LED off and on, but we think that the count rate also very slightly increased. Note, that PMT north is also the furthest away from the LED.

Also we saw a difference between single- and multi-photon events at PMT south.

We exchanged the old BBO of the Cobra's FCU with a new one. The output power of the Cobra was around 120mJ. In the end, we achieved a UV power of about 21mJ. In addition, we optimized the fiber-coupling to the wavemeter. 

Since yesterday, channel 0 of the CAEN PS is dead (no voltage even without cable).
Changed detector south to channel 3.

• Very long cooling times are needed after deceleration to cool the decelerated beam.
  
• Electron energy and decelerated beam are not well matched.
  
• 229Th is cooled even later after the other ions
  
• Even after scraping some contaminats remained that were either rebunched and show side bands. or move around as a "cloud".
  
• This can be seen on the detectors (e.g. particle dector, but also PMTS) as a flat bump in the folded "accu" spectra. the signal decreases with time. I.e., It moves around the ring with a frequency matching the one of the wanted species but with some "phase offset" of about half a ESR revolution. The signal is ratger stron but vanishes ("decays") after some time. Probably finally scraped og
  
• It is very tigth to set the scrapers correctly (and the particke detector).
  
• Fortunately the ion beam optical setting is such that the scraper in the south is in optimal position just at its "Endlage inne" (values see below)
  
• SIS intensiteis have increased but are still on average a factor 3-4 lower than one year ago.
  
• As a sidenode: For optimal scraping, the beam decelerated, debunched, cooled, scraped and rebunhced. Thus, one can see if there are contaminants, and, in consequence clean the beam better from unwanted species.
  
• The bunches are still quite long given the number of ions, increasing of the bucket fill from 1.0 to values large than 1.4 gives problems such as phase shifts , ande changes even inbetween a waiting/measurement time. to be discussed with the specialists on monday
  

• The cooling energy is set 100V higher - which also matches better to a recalculated scanning range; ( PTB 104513 V, Ohmlabs 1040509 V). This better matching improves cooling times but is till not optimal. It is noted, tha tthe cooling times are long since a broad cloud of ions is decelerated, and the electron current is low (was 50 mA, now 60 mA).
  
• Electron current increased 50 mA -> 60 mA.
  
• Scrapers are moved in in two steps with an intermediate posiions to mitigate the problem of overshoots when driving. Before rebunching they are slightly moved out to make room for the slightly larger
  bunched beam.
  
• Due to the change of the voltage the bunching frequency has changed (see post of the start of the test measurements); electron cooled DC beam and bunched beam are (alomost) matched using the RSA in 100kHz scale. The new reference frequency on the RSA are (old: 243.750625MHz, rev. frequency 1.542728 MHz, 158 harm - new: 243.815 MHz, 1.54313 MHz).
  [New settings for timing and scraper position will be attached as fotos; an emergency backup of the settings are stored in an earlier post).
  
• The cooler actually drags the ion very slowly to its final position after ~30 s just before rebunichng (visible by the shift of the peak relative to the marker just before rebunching). This is interpreted as and effet of the power supplies only very slowly reaching a final value to within a few kHz.