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  Laser Cooling Experiment 2021, Page 3 of 5  Not logged in ELOG logo
New entries since:Thu Jan 1 01:00:00 1970
ID Date Author Category Subjectdown
  12   Wed May 12 08:41:36 2021 SebastianAnalysisLaser stability
During night shift the laser was very stable! Only minor fluctuations occured in the UV
  13   Wed May 12 08:42:49 2021 SebastianAnalysisLaser scans / coastig beam / no ecooler
Attached you'll see a first laser scan of ~100GHz in the UV.
Attachment 1: Screenshot_(156).png
Screenshot_(156).png
  29   Wed May 12 23:45:23 2021 Ken UeberholzGeneralLaser does not reach the exit window
High rates on the detector at 50mm positions, laser does not seem to reach the exit window.
  74   Sun May 16 05:09:04 2021 TeamGeneralLaser cooling with 482ps
we see laser cooling with 482ps pulse length
  76   Sun May 16 05:24:00 2021 TeamGeneralLaser cooling with 285ps
we also see laser cooling with 285ps pulse length
  78   Sun May 16 07:03:07 2021 TeamGeneralLaser cooling with 166ps
We saw some indications of laser cooling @ 166ps pulse length
  65   Sat May 15 09:50:31 2021 TeamRunsLaser cooling of....
H=2
H=7
H=10
H=20
H=30

We performed several scans:
Close to the bucket middle
Over the bucket
Over the bucket, jumped to the "red side" 
of the bucket and captured and cooled the 
beam again.

Laser settings:
7 times revolution frequency and 740ps 
pulses - - > 3.4 +/- 1.2 GHz

Still to do:
Switch to 240ps pulses - - > 5.8GHz 
+/-1.3 GHz

Maybe:
Switch to 117ps pulses - - > 11.0 +/- 0.8 GHz
BUT here we have less laser power (max. 50 mW right after BBO crystal, so maybe only 30 mW at the laser-ion overlap)
available. Maybe we are lucky and it is 
enough to cool also the ion beam. :) 
  27   Wed May 12 22:57:41 2021 SebastianGeneralLaser Reprate
laser reprate is seven times the revoolution frequency: 9.038283 MHz
pulse length: 735ps
  82   Sun May 16 22:11:49 2021 TeamGeneralLaser Polarisation values
maximal transmission of PBSC (257/514 pbsc was used in combination with xlp12 detector and visual on a screen):

L/4 @ 276° & L/2 @ 348°                -->   p-polarized light


L/4 gleich auf 276° & L/2 auf ~19°     -->   s-polarized light
current position 22:15 p.m.

now we have some fun ! :D
  56   Fri May 14 11:01:33 2021 BenediktCalibrationLaser Beam adjusted
The laser beam was adjusted in his position to overlap better with the ions.

Ion beam is destroyed at scraper position 1VO 6 mm and 2VO 4 mm; the laser beam looses half its power at 1VO 6mm and 2VO 4 mm.

EDIT: In the Schottky spectrum, we saw a stronger "cut" from the laser beam with slightly different settings in the TEM system. Later today, we could maybe finetune the ion-laser overlap while observing this "cut".
  14   Wed May 12 09:04:48 2021 SebastianDAQKeysight AUtoCal
Attachment 1: IMG_20210510_143940_resized_20210512_090353546.jpg
IMG_20210510_143940_resized_20210512_090353546.jpg
  Draft   Wed May 12 02:16:25 2021 Danyal, LarsAcceleratorIon beam position
Laser Position with scrapers verified. 
1HA: impossible to scratch laser beam, still there at -1.0 mm
2HA: +3mm --> half the laser power on detector; +4.5mm --> gone

2VO: interlock, impossible to move (beam diagnostics is informed and will check)
1VO: +0.2mm --> half laser power, +1.2: laser gone (-1.0mm: also gone)

Ion beam adapted to measured laser beam, Target bump position: -22mm (was -18mm before)
Ion beam position verified with scrapers:
1HA: -1.0mm --> still there
2HA: +4.0mm --> beam gone
Target bump angle: unchanged (+1.2 mrad)
  16   Wed May 12 09:09:15 2021 SebastianDAQFluorescence
fluorescence with detector in parking position
fixed laser wavelength
electron cooling ON, 
BUT we saw strange drifts in the Schottky spectra. It seems to be that these drifts come from the electron cooler! are the drift tubes grounded?

the drifts shift the ion beam over the transition which result in an increase of the XUV anode signal
Attachment 1: 1029967nm.png
1029967nm.png
  83   Mon May 17 08:05:42 2021 TeamGeneralEnd of beamtime
~ 8 a.m.
  63   Sat May 15 09:22:41 2021 Sebastian AcceleratorEkühler
Settings für Ekühler an und aus in SC4 und 
5
Attachment 1: IMG-20210515-WA0000.jpg
IMG-20210515-WA0000.jpg
Attachment 2: B5FE1031-7FFD-44D3-92B0-75E0784718D9.jpeg
B5FE1031-7FFD-44D3-92B0-75E0784718D9.jpeg
  64   Sat May 15 09:23:52 2021 SebastianAcceleratorEkühler
Tab "Kühler Elektronenstrahl"
An Gerät schicken
  55   Fri May 14 09:40:04 2021 NightshiftRunsEcooling vs laser wavelength shift, coasting beam, laser stronger than Ecooling
Last three pictures where taken after 
first laser ion beam overlap adjustments

It seems to be that the interactions are 
better. We also see the laser earlier and 
stronger in the schottky 
Attachment 1: IMG-20210514-WA0017.jpg
IMG-20210514-WA0017.jpg
  37   Thu May 13 02:45:29 2021 SebastianAnalysisESR pressure
Attachment 1: IMG_20210513_014506_resized_20210513_024017156.jpg
IMG_20210513_014506_resized_20210513_024017156.jpg
Attachment 2: IMG_20210513_014518_resized_20210513_024017559.jpg
IMG_20210513_014518_resized_20210513_024017559.jpg
Attachment 3: IMG_20210513_014524_resized_20210513_024017847.jpg
IMG_20210513_014524_resized_20210513_024017847.jpg
Attachment 4: IMG_20210513_014606_1_resized_20210513_024018452.jpg
IMG_20210513_014606_1_resized_20210513_024018452.jpg
Attachment 5: IMG_20210513_014606_resized_20210513_024018145.jpg
IMG_20210513_014606_resized_20210513_024018145.jpg
Attachment 6: IMG_20210513_014627_resized_20210513_024018757.jpg
IMG_20210513_014627_resized_20210513_024018757.jpg
Attachment 7: IMG_20210513_014636_resized_20210513_024019062.jpg
IMG_20210513_014636_resized_20210513_024019062.jpg
Attachment 8: IMG_20210513_014700_resized_20210513_024019366.jpg
IMG_20210513_014700_resized_20210513_024019366.jpg
  35   Thu May 13 01:55:15 2021 SebastianGeneralESR amplifier reset / laser check
we had to go into the ESR because the amplifiers hooked up. both amplifiers were resetted!

we also checked why we didnt see the laser at the exit window.
Laser Shutter @ the exit is closed......................... E02VVLF2t needs to be opened!
Attachment 1: IMG_20210513_014345_resized_20210513_015540959.jpg
IMG_20210513_014345_resized_20210513_015540959.jpg
Attachment 2: IMG_20210513_014353_resized_20210513_015541291.jpg
IMG_20210513_014353_resized_20210513_015541291.jpg
  59   Fri May 14 22:04:25 2021 TeamAcceleratorESR OPEN ; NO BEAM -> Reset cooling device
we had to open the ESR to reset a cooling device
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