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  Nuclear hyperfine mixing in 229Th89+ 2025, Page 3 of 4  Not logged in ELOG logo
Entry  Sat Jun 21 01:40:31 2025, Carsten, Alex, Anton, Rodolfo, Hiroshi, Accelerator, beam parameters 
The revolution frequency for the measurement condition is: 1.542728 MHz.
The electron cooler voltage is: 104411 V.
Entry  Sat Jun 21 00:52:07 2025, Carsten, Accelerator, Summary of the last days (bunches wiht several isotopes still in ) / frequency of the  
Initially, we has very low SIS beam intensities in the 1e8 region. Setting up ESR wiht Stacking etc. turned out to be extremly tedious for the ESR crew.
Yet, they managed to get stochastic ooling working early on.

Accumulation with the new "stochstic cooling only" scheme essentially does not saturate even after 40 injections or so.
One problem was that the beam often got lost at deceleration and not reliable / reproducable conditions could be achieved.

Also the secondary beam and partilce ID could finally be established (see earlier posts). During deceleration often the partilces were got lost again.

In the decelerated bunch at least 7 isotopes were decelerated (and not only one):

The frequencies were

@ 400 MeV/u in SC 3:
    [1] 242.27986 MHz
    [2] 242.82623 MHz + 27.5 kHz
    [3] 242.853 MHz + 54.375 kHz 229Th
    [4] 242.878 MHz + 79.375 kHz
    [5] 242.936 MHz + 137.5 kHz
    [6] 242.959 MHz + 160 kHz
    [7] 242.982 MHz + 183.75 kHz

decelerated to 190 MeV/u:
    [1] 243.6925 MHz
    [2] 243.72213 MHz + 29.6 kHz
    [3] 243.750 MHz + 57.375 kHz 229Th --- Reference on Schottky scope
    [4] 243.7768 MHz + 84. kHz
    [5] 243.8376 MHz + 145 kHz
    [6] 243.863 MHz + 170.6 kHz
    [7] 243.687 MHz + 194.625 kHz

Thursday night (19.6. -> 20.06.) a first scraping was established.


In order to cleanly scrape the peaks Sergey Litvinov devised a new pattern:

At the low energy (190 MeV/u) the bunch is unpacked, cooled, scraped and rebunched for the measurement.

Some details of th eabove can be found in the acclerator log.

The problem with the beam losses were solved with large cooling phases at the end of the accumulation cycle.
Entry  Sat Jun 21 00:23:22 2025, Rodolfo, Laser, Dye Farbstoff_FL27.jpg
I have prepared new (fresh) dye solutions of Fluorescein 27: 2 charges. They are in the Safety Cabinet (Sicherheitsschrank) in the ESR Laser lab
Entry  Fri Jun 20 15:58:21 2025, Wilfried, Konstantin, Simon, Laser, Laser stepwidth 
From previous Bi-Beamtimes, we expect the width of the transition to be >50GHz (FWHM). The current step width is 0.002nm which corresponds to 8GHz, so the laser would be in resonance for 6 steps.
We should aim for at least 5 steps in resonance.

line width (sigma) >20GHz
FWHM ~50GHz
step width (fundamental) 0.004nm (4GHz)
step width (doubled) 0.002nm (8GHz)
Entry  Fri Jun 20 11:25:32 2025, Julien, Kristian, Konstantin, Laser, Automated laser scans  
In contrast to entry E12, the cabling for the automated start of the laser scan is now connected to IO3 of sddsc221.
Entry  Fri Jun 20 06:37:51 2025, Konstantin, Accelerator, Position of contaminants 
I checked the positions of the contaminants. Therefore, I drove the scrapers and observed the signal at the Schottky detector

While the vertical positions are identical for all scrapers, the horizontal positions deviate due to the dispersion in the cooler section

Scraper -83.75kHz -26.875 0 61kHz 83.25 110.625
GECEDS1VU -0.5 -0.5 -0.5 -0.5 -0.5 -0.5
GECEDS1HA (from 75mm) -4 -5 -5.2 -6.6 -6.9 -7.2
GECEDS1HA (from -75mm) -11.8 -12.8 -13.3 -14.5 -15.1 -15.7
GECEDS2VU 0.9 0.9 0.9 0.9 0.9 0.9
Entry  Wed Jun 18 20:24:01 2025, Carsten, Shahab, Ragandeep, Danyal et al. (the dayshift) and ESR crew, Accelerator, 229Th89+ identification 245_MHz_Schottky_229Th89.jpg
We believe to have identified the 237U92+ and the 229Th89+ peaks. 

Using the Schottky resonator at about 244 MHz and taking the 123rd harmonic: 
The Schottky peak of 237U92+ should be at 242.7975 MHz and the one of 229Th89+ at 242.8494 MHz. 
The peaks should be ~52 kHz apart.

We have used:  
gamma_t	= 2.355 
alpha_p = 0.18 
Entry  Wed Jun 18 19:05:28 2025, Carlo, Zac, Shahab, Ragan, Analysis, PID with rionid Schermata_2025-06-18_alle_19.03.04.pngE142_TEline-ESR_229Th.lppRSA01-2025.06.18.18.06.02.162.tiq_spectrum.npzSchermata_2025-06-18_alle_19.32.53.png
For PID with rionid we used: 
- LISE file from last year (attached.
- .npz file from 410 RSA (attached).
Entry  Wed Jun 18 14:01:40 2025, Julien, Konstantin, Stefan, Rima, , Ion bunch on PMTs Bildschirmfoto_bunch_on_PMT_2025-06-18_14-11-44.png
Apparentlty did not work yesterday evening (no signal), but looks fine now (see attachment)
Entry  Wed Jun 18 11:44:15 2025, Julien, Konstantin, Stefan, Rima, , Jitter CFD 
Pulses on photodiodes in entry 20 

1. seem wide, so we also looked at qswitch signal; also seemes wide.
2. Have a tail

1.:

We investigated this and came to the conclusion, that the CFD is the issue:
- On an oscilloscope, when looking at both HF signal (CFD input) and CFD output, there is a 2ns jitter.
- The same jitter is visible when looking at the CFD output when triggering on a freq. generator signal with same frequency and amplitude as HF signal (1.54263 MHz; 1V peak to peak).
- There is not significant jitter when comparing the CFD output and the qswitch signal

We tried differents CFD (also a leading edge CFD / different thresholds), but this did not significantly improve what we saw on the oscilloscope.
Applying a 10MHz filter to the HF signal only made the jitter worse.
There might be an option to get a logic (NIM) signal from ESR instead of the sin-signal
Alternatively, one could think about using a PLL.
Note: the 2ns might also be limited by the trigger of the oscilloscope. We saw that if the trigger of the oscilloscope is not on the steepest part of the HF signal, the jitter "gets worse".

2.:

We saw on the qswtich signal, that there are instances, when  the q-switch signal is too early; 
Ww will try to find out which NIM module between the CFD and the final qswitch signal causes this
Preliminary: It's coincidance crate
Entry  Wed Jun 18 08:07:17 2025, Julien, Konstantin, Laser, new FCU Calibration 2025_06_18_FCU_Cal_Table.JPG2025_06_18_FCU_Cal_Plot.JPG
UV power was not stable but dropping from ~18 mW to 13 mW after opening COBRA shutters.
New calibration of frequency conversion unit:

Wavelength/nm       Position/Steps
554,0001            383029
553,0000            386604
552,0001            390229
551,0000            393954
550,0001            397679
549,0001            401404
548,0001            405104
547,0001            408829

now stable at ~19-20 mJ depending on wavelength

Table of dataset: Attachement 1
Plot of dataset: Attachement 2
Entry  Wed Jun 18 07:59:00 2025, Julien, Konstantin, Laser, Phase-offset IMG_3889.jpgIMG_3888.jpgIMG_3891.jpgIMG_3892.jpg
We recognized that the output power of the pump laser was instable when externally triggered with 200kHz (stand-bye frequency of ESR). Therefore, we changed the coarse timing offset of the pockels cell trigger compared to the flash lamp pulse from 215µs to 219.9µs. 
Thereby, the output power increased from ~600mJ to 620mJ, and the PTP stability improved from 15% to 10%. The RMS stability improved from 2% to 1.2 %. With these settings we had UV pulse energies of 20mJ.
Entry  Wed Jun 18 03:12:25 2025, Rodolfo, Laser, Beam Stabilization MRC-Settings_2025_06-18.JPG
The laser beam pointing has changed, even thought the MRC settings are the same as given in Entry 5 (this elog). This could be caused by a droping of the laser output energy which is now 13,8 mJ @275 nm
Entry  Wed Jun 18 01:58:02 2025, Esther, Alexis, Anton, Rodolfo, Carsten, Accelerator, No Bunched Beam Bildschirmfoto_PD_PMTSouth_2025-06-18_1.png
The Bunching is not set properly. We do not see the ion bunch with the Photomultiplier.
Entry  Wed Jun 18 00:56:28 2025, Carsten, Rodolfo, Anton, Alexis, Esther, , beam overlap with t-scrapers 
When testing the overlap between laser and ion beam we observed the following positions:

motorion beam position (mm) from outsideion beam position (mm) from inside
GECEDS1VU 0 6.5
GECEDS1HA -22.5 -13.5
GECEDS2VU 1 8.5
GECEDS2HA -20.5 -10


Note: To move GECEDS1VU the corresponding horizontal drive (GECEDS1HA) has to be at 2 mm.
Entry  Wed Jun 18 00:33:56 2025, Esther, Alexis, Anton, Rodolfo, Carsten, DAQ, R4l-41 
We have some issues with the RIO computer R4l-41 (DAQ1). We had to switch off completely twice. Only then it reacted properly. Maybe a problem with the network at about 00:00 o'clock?
Entry  Tue Jun 17 19:25:30 2025, Rodolfo, Accelerator, T-Scrapers in E-Cooler Scrapereinstellung_am_E-Kühler.pdf
Here are the instructions to drive the T-Scrapers inside the ESR Electron Cooler

  • ECEDS1VU: Verriegelt mit ECEDS1HA. Der Antrieb kann nur fahren
    wenn der Antrieb ECEDS1HA in Position -4,0 steht.

  • ECEDS1HA: Verriegelt mit ECEDS1VU. Der Antrieb kann nur fahren
    wenn der Antrieb ECEDS1VU in Stellung EI steht.

  • ECEDS2VU: Verriegelt mit ECEDS2HA. Der Antrieb kann nur fahren
    wenn der Antrieb ECEDS2HA in Position 0,0 steht.

  • ECEDS2HA: Verriegelt mit ECEDS2VU. Der Antrieb kann nur fahren
    wenn der Antrieb ECEDS2VU in Stellung EI steht.

According to Boywitt/Schuhmacher, BEA-MEI. Date: 28.07.2021
Entry  Tue Jun 17 16:33:16 2025, Carsten, Simon, DAQ, Gate Q-swtich 
The gate generator of the Q-switch signal for the Vuprom TDC was set to 10ms.
Entry  Mon Jun 16 22:27:01 2025, Carsten, Simon, DAQ, Thresholds  
We also adjusted the thresholds for the mesytic.
Doing that, we noticed that one of the trafos is broken (5th row, middle).

PMT channel Threshold
South 5 35
Middle 6 16
North 7 16
Entry  Mon Jun 16 21:47:23 2025, Carsten, Wilfried, Simon , Detectors, New threshold values for PMTs 
We adjusted the thresholds for the PMTs and increased the voltage of PMT middle to 2.7kV

PMT Model Operation Voltage Threshold (mV)
South ET9422B Broadband -1750 V 30
Middle ET9423B Smallband -2700 V 18
North ET9423B Smallband -2650 V 10
ELOG V3.1.5-fc6679b