 Thu Apr 7 11:11:31 2022, Max, Sebastian, Laser, dye changed, pulse energy measurements
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We changed the dye at 10am.
We increased the pump power for the dye Laser to 480mJ (before 450mJ). New calibration factor is 29 for Quanta Ray monitor signal.
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Fri Apr 8 00:06:37 2022, Patrick, Laser, Connection to the laser pc
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To login to the laser pc use the command
xfreerdp -g 1920x1080 -u atplaser atppc023.campus.gsi.de |
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Fri Apr 8 02:14:05 2022, Wilfried, Laser, Laser timings adjusted
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Since we use the middle window as a reference for the laser pulse timing, the fact that the window is 2.25 m behind the target has to be taken into account.
From here the ions have 10 ns less time of flight to the middle of the electron cooler than they need for half a revolution. The signals were still symmetrically
aligned around the reference bunch as it was done yesterday. Therefore, the delay of the laser pulse was reduced by 10-ns on the oscilloscope, which led |
Fri Apr 8 03:54:39 2022, Patrick, Laser, Q-switch window 
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The solution of increasing the Q-switch window from 2us to 5us described in [I]ID:148[/I] fulfills its purpose, but the window is unstable.
We saw the laser jumping across the screen which was because the Laser had a lot of hickups.
The hickups come from the signal which determines the duration of the window.
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Fri Apr 8 08:17:52 2022, Sebastian, Laser, Laser Ext Trig is working
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We (Max, Kristian, Danyal, me) fixed the "external trigger" problem.
1.) The delay between lamp sync and Q-switch trigger was too long. The delay must be 200µs (3rd picture)!
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Fri Apr 8 11:16:57 2022, Kristian, Laser, Wavemeter
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We changed the fiber to the wavemeter. The third fiber worked best and we could operate the WM at low exposure times, i.e., below the laser repetition rate.
We used the neutral density filter to adapt the laser power that only one laser pulse is measured by the WM each time (Exposure time =34ms)
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Sat Apr 9 05:26:25 2022, Patrick, Laser, Wavemeter
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| The wavemeter still shows large spikes from time to time. The exposure time is still at 34ms. |
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Sat Apr 9 06:42:23 2022, Kristian, Laser, Laser step size
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| We changed the laser step size to 0.002 nm which corresponds to 5.75 GHz. |
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Sat Apr 9 16:55:19 2022, Rodolfo, Laser,
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16:15 I have changed the dye (of both oscillator and amplifier).
16:27 I have increased the pump energy (@ 532 nm) from 476 mJ to 507 mJ.
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Sat Apr 9 19:09:57 2022, Rodolfo, Laser, Optimization - Resonator of dye laser
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I have tuned a bit the resonator of the dye laser.
The total output energy after the main amplifier is 86 mJ (@ 645,6 nm)
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Sun Apr 10 08:53:26 2022, Kristian, Max, Laser, Timing verified
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timing is still good.
we checked the relative timing between laser and ions. the time difference between photodiodes, PMTs and particle detectors is still the same as original |
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Sun Apr 10 11:11:18 2022, Kristian, Max, Laser, additional WM readout
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since the WM readout still does not work reliably, I started a python script at atppc023 that saves timestamp and wavemeter frequency. in folder wavemeter
at the desktop.
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Sun Apr 10 15:29:53 2022, Rodolfo, Laser, Status - Laser system
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We have checked the laser system.
- The pump laser has ~ 23Mio shots. The total output energy has dropped to about 475 mJ. Maybe it is time to install new fresh flashlamps. In case the |
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Mon Apr 11 11:05:35 2022, Sebastian, Kristian, Laser, Check laser power
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we checked the UV laser power at 10:15 am. It was only 8.5 - 9 mJ. Pumping power was 460 mJ, which is the maximum output of the current system. We should
change the flashlamps soon |
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Mon Apr 11 18:46:31 2022, Rodolfo, Sarper and Konstantin, Laser, Alignment-check
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We cross-checked the laser-ion alignment. The horizontal position was optimized. However,
since the laser beam is much larger than the ion beam, this was not an issue for measurements, which
have been performed during the last shifts.
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Mon Apr 11 18:57:18 2022, Rodolfo, Laser, New flashlamps
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We (Sarper, Konstantin and me) have changed the old flashlamps (with ~ 26 Mio. shots) by new "fresh" ones. We have also exchange the dye. Here are some
parameters of the laser we measured with the new flashlamps and dye*:
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Mon Apr 11 22:14:51 2022, Konstantin, Sarper, Laser, Changing of the wavelength range
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| It is planned to change the scan range of the laser wavelength from 322.41 - 322.0 nm to 322.01 - 321.6 nm @ 4 a.m. |
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Tue Apr 12 15:05:56 2022, Rodolfo, Laser, Laser status
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We have checked the laser power at 14:15 *
- Pump energy after Q-Ray @ 532nm: 559 mJ.
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Wed Apr 13 15:41:29 2022, Rodolfo & Sarper, Laser, Laser status
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We have checked the power of the laser and optimized it "a bit".
- Seed energy for the Cobra @ 532 nm: 508 mJ (before 496 mJ)*
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Thu Apr 14 19:46:46 2022, Sarper & Konstantin & Rodolfo, Laser, Laser power
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We checked the laser power before starting the new scan range.
- Seed energy before Cobra @ 532 nm: 513 mJ (before 499 mJ).
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