 Thu Mar 3 17:34:42 2022, Rodolfo, Laser, Pump Laser 
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We have issues with our Pump Laser (Spectra Physics - Quanta Ray Pro). After the service made on mid Dezember (2021) the laser does not get started. After contacting the service many times, the technicians think it can be an issue with the flashlamps.
- Flashlamps installed technician on 15.12.2021: FAILED.
- Flashlamps installed by Rodolfo on 21.01.2022: FAILED.
- Flashlamps installed by Rodolfo on 08.02.2022: WORK, however
the power is dropping extremelly fast. The measured power on 08.02.2022 was 21.6 W. On 01.03.2022 we measured 17,8 W (for 2.7 Millon shots). The flashlamps should stand 30 Millon shots without losing too much power. |
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Tue Mar 29 21:37:13 2022, Rodolfo, Laser, Pump Laser
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The gold "reflectors and end plates" of our pump laser (Quanta-Ray PRO) have been exchanged by new ones.
- Output power after Oscillator and Amplifier (@ 1064 nm): 41 W.
- Output power after Second harmonic crystal (@ 532 nm): 18.2 W.
- Aditionally, we (Simon and I) have replaced the axial blowers in the power supply.
The picture shows the "old" gold reflectors. |
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Thu Apr 7 10:10:31 2022, Ragan, Yuri, Danyal, Accelerator, Problem in UNILAC
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The power supply of the UNILAC magnet is broken. The repair will take up to 6-7 hours. |
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Fri Mar 18 16:58:26 2022, Rodolfo, Accelerator, Pressure at North-East Arc
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The pressure at the north-east arc of ESR, where the laser window is located, looks suspicious. The sensor E01LF02 shows a value of 7.26E-8 mbar. For comparison I have also upload a photo taken on 07.02.2022 where the pressure was 4.62E-10. We have contacted the vacuum expert and asked for his opinion. Waiting for the reply ...
Bilder: R. Sánchez |
 Mon Mar 21 09:18:28 2022, Rodolfo, Accelerator, Pressure at North-East Arc
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Our vacuum expert has reply. The "IZ Pump" in this region was off.
| Quote: | The pressure at the north-east arc of ESR, where the laser window is located, looks suspicious. The sensor E01LF02 shows a value of 7.26E-8 mbar. For comparison I have also upload a photo taken on 07.02.2022 where the pressure was 4.62E-10. We have contacted the vacuum expert and asked for his opinion. Waiting for the reply ...
Bilder: R. Sánchez |
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Wed Sep 8 21:44:55 2021, Rodolfo, General, Preparation
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Status | Arbeitspaket | Kommentare
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| Laser und Laserlabor |
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*** | Farbstofflaser | Elektronik wurde erneut.
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Fri Apr 1 18:30:38 2022, Carsten, Detectors, Positions / Voltages threshlds for particle detectors
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DC beam 238U92+ (205kV, e-beam)
We used the detector NA_SZ to determine the central primary-beam (238U92+) position by observing the Schottky-signal while moving the detector inside.
The beam position is 43 mm (wehre the beam is almost gone").
NA_SZ
In the pocket of the NA_SZ we mounted the thick "old pilot U" scintilator since the original one foreseen is defect, see other post.
CFD Model CAEN N853
800V position 20mm pulse height 1V
750V position 10mm pulse height 0.82V, CFD, Ch7, 247, (247mV according to manual)
SA_SZ
Check positions and voltages of the detector behind the cooler
Yesterday the setting of the scope was x10, so the values written in that post were wrong.
At present we position -20, 1400V, pulseheight 1C, CFD, Ch6, 250 (250mV according to manual)
Scraping from the inside with NI_SZ touches the primary ion beam at 28 and destroys the beam at 27 mm. Thus, the beam presently is on a very inner orbit. |
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Thu Mar 31 17:56:32 2022, Konstantin, DAQ, Photodiode test signal
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| We used a signal generator to provide a 4MHz dummy-RF signal. This was divided by a factor of 2 for laser-"bunch" synchronization and by a factor of 200 for to provide the stop-tigger attached to the DAQ. With this Dummy-RF we were able to measure the relative arrival times of the laser at the photodiodes located in the laser towers. Note that the signal of the southern photodiode arrives first. This is because the scale of the time axis is given in (10/3ns)-bins since the last common-stop. |
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Fri Mar 25 14:31:24 2022, Rodolfo, Laser, Photodiode signal SO in the Messhütte
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Measured at the Panel "Messhütte - Laserhütte", BNC "Fast PD / SO".
- Average over 256 samples |
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Thu Mar 24 16:59:35 2022, Rodolfo, Laser, Photodiode signal SO
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Fast Photodiode signal at the "SO-Bogen" (South-east arc).
- Average made over 250 samples.
- The photodiode is placed after two HR (high reflexion) mirrors. |
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Sat Apr 2 18:17:31 2022, Yuri, Accelerator, Photo-Identification
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Just a photo of the ID |
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Tue Mar 29 12:47:26 2022, Ken Ueberholz, , Parameter setting for XUV and copper mirror detector
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Some Default Settings for the XUV
Detector. The copper
mirror should always move fully in.
Possible positions: Between 0mm and 147mm.
Background was
very high for anything higher than 100mm
in the last
experiment. 50mm was optimal. This should
be tested again
with repaired and modified shields.
Good default values for the XUV detector
parameters have
been proven before to be:
Cathode: -5V
Movable shield: 0V
Fixed shield: 0V
Main coil: 8A
Secondary coil: -2.4A
(negative values set in hardware, only
positive software
inputs are possible) |
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Fri Apr 1 23:47:45 2022, Carsten, Detectors, PMT thresholds / PMT north does not allow voltage abow ~ -1kV
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Checked thresholds of PMT with beam and without beam.
The PMT "south" which is now at the gas-jet target has burst-like pulses with a train of many short pulses of duration of about 1us. The signals are taken out of the ADC of the 2nd DAQ (but are still in the VUPROM TDC).
The PMT "middle" (broad-band VUV) has a quite high count rate of about 4-kHz at a few 10e7;; ions in the ring. The rate is very low without ions in the ring but it does not fully scale to low intensities.
At low intensities of a few 10e5;; we still have more than 100 Hz.
For a PMT voltage of -1800V a threshold of 20mV was set which is ok an d we leave it
Note: We see a noise beat of 6ns and 55ns with amplitude of about 15mV to 20mV. The high frequency disappears if we use a battery scope.
PMT "north" small-band VUV
We tried to put the voltage to the wanted level of -2500V. It was not possible to set a voltage higher than about -1000V. WIth this voltage the PMT draw a current of about 200uA and at a voltage above this value it dropped to zero and switched off.
We need to have a closer look at the PMT in the ESR tomorrow with some specialist knowledge. |
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Tue Apr 5 11:14:52 2022, Sebastian, Kristian, Pierre-Michel, DAQ, PMT over wavelength histogram v2
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Today we finalized the PMT over wavelength histogram in:
Analysis/Histograms/Step2_Anl/LabView/laserscan
Currently the histogram shows the PMT middle signal on the y axis.
Remark: Tomorrow we create this kind of histogram for all PMTs. |
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Mon Apr 4 15:27:31 2022, Sebastian, DAQ, PMT over wavelength histogram
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Kristian and I tried to create a "PMT over wavelength" histogram under step2Anl/LabView.
Unfortunately, the code ist still in progress and does not work yet.
The current code can be found in the TldaAnlProc.cxx |
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Wed Mar 23 11:20:55 2022, Simon, Detectors, PMT operating voltages
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During the testing of the PMTs the following operating voltages were applied:
PMT Cu: -1300V
PMT Nord: -2500V
PMT Mitte: -1800V
PMT Süd: -1800V
Further optimization will be necessary during background measurements. |
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Fri Apr 1 22:01:14 2022, Konstantin, Detectors, PMT operating voltages
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> During the testing of the PMTs the following operating voltages were applied:
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> PMT Cu: -1300V
> PMT Nord: -2500V
> PMT Mitte: -1800V
> PMT Süd: -1800V
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> Further optimization will be necessary during background measurements.
Currently, PMT Süd shows a strange behavior resulting in after-pulses up to 1µs. Therefore, the high-voltage was reduced to -1500 V.
However, the after-pulses remain. This should be investigated in more detail at some other point. |
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Tue Apr 12 14:52:19 2022, Rodolfo, Detectors, PMT Nord, Middle. Datasheets
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Attached are the datasheets for the solar-blind PMTs.
- PMT Nord. Type 9423. SN: 650
- PMT Middle. Type 9422. SN: 1049 |
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Tue Apr 5 13:24:40 2022, Kristian, Detectors, PMT Cu
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HV cable was in wrong channel in power supply. Now it is back to the correct position. Checked connection at the PMT. |
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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)
The laser wavelength read by the wavemeter appears to be more stable (on the windows computer). We can see the histogram once the present scanning is finished. |