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  Laser Cooling Experiment 2021, Page 3 of 5  Not logged in ELOG logo
Entry  Wed May 12 08:41:36 2021, Sebastian, Analysis, Laser stability 
During night shift the laser was very stable! Only minor fluctuations occured in the UV
Entry  Wed May 12 08:42:49 2021, Sebastian, Analysis, Laser scans / coastig beam / no ecooler Screenshot_(156).png
Attached you'll see a first laser scan of ~100GHz in the UV.
Entry  Wed May 12 23:45:23 2021, Ken Ueberholz, General, Laser does not reach the exit window 
High rates on the detector at 50mm positions, laser does not seem to reach the exit window.
Entry  Sun May 16 05:09:04 2021, Team, General, Laser cooling with 482ps 
we see laser cooling with 482ps pulse length
Entry  Sun May 16 05:24:00 2021, Team, General, Laser cooling with 285ps 
we also see laser cooling with 285ps pulse length
Entry  Sun May 16 07:03:07 2021, Team, General, Laser cooling with 166ps 
We saw some indications of laser cooling @ 166ps pulse length
Entry  Sat May 15 09:50:31 2021, Team, Runs, Laser 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. :) 
Entry  Wed May 12 22:57:41 2021, Sebastian, General, Laser Reprate 
laser reprate is seven times the revoolution frequency: 9.038283 MHz
pulse length: 735ps
Entry  Sun May 16 22:11:49 2021, Team, General, Laser 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
Entry  Fri May 14 11:01:33 2021, Benedikt, Calibration, Laser 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".
Entry  Wed May 12 09:04:48 2021, Sebastian, DAQ, Keysight AUtoCal IMG_20210510_143940_resized_20210512_090353546.jpg
 
Entry  Wed May 12 02:16:25 2021, Danyal, Lars, Accelerator, Ion 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)
Entry  Wed May 12 09:09:15 2021, Sebastian, DAQ, Fluorescence 1029967nm.png
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
Entry  Mon May 17 08:05:42 2021, Team, General, End of beamtime 
~ 8 a.m.
Entry  Sat May 15 09:22:41 2021, Sebastian , Accelerator, Ekühler  IMG-20210515-WA0000.jpgB5FE1031-7FFD-44D3-92B0-75E0784718D9.jpeg
Settings für Ekühler an und aus in SC4 und 
5
Entry  Sat May 15 09:23:52 2021, Sebastian, Accelerator, Ekühler 
Tab "Kühler Elektronenstrahl"
An Gerät schicken
Entry  Fri May 14 09:40:04 2021, Nightshift, Runs, Ecooling vs laser wavelength shift, coasting beam, laser stronger than Ecooling IMG-20210514-WA0017.jpg
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 
Entry  Thu May 13 02:45:29 2021, Sebastian, Analysis, ESR pressure 8x
 
Entry  Thu May 13 01:55:15 2021, Sebastian, General, ESR amplifier reset / laser check IMG_20210513_014345_resized_20210513_015540959.jpgIMG_20210513_014353_resized_20210513_015541291.jpg
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!
Entry  Fri May 14 22:04:25 2021, Team, Accelerator, ESR OPEN ; NO BEAM -> Reset cooling device 
we had to open the ESR to reset a cooling device
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