ELOG E142

DAQ improvement

Concerning ID 146 a new histogram for accumulating data (no cleaning histograms) can be found under

Step2_Anl/TDC/TDC***_accumulated_***

152

Fri Apr 8 08:17:52 2022

Sebastian

Laser Ext Trig is working

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)! 

2.) The settings from the left Dual Timer (upper and lower part) in the ESR Laser Lab (above QuantaRay laser) were wrong and are now adjusted. Settings are depicted in the attached photos (1st and 2nd pic).

4th picture shows the pulse train of the pump laser.

151

Fri Apr 8 06:53:29 2022

Ragan

Runs

NTCAP data taking

NTCAP is taking data since 07.04.2022 23:53:47

Carrier Frequency: 242.2 M
IQ Rate (S/s): 10 M
Reference level (dBm): -30

SC_2022-04-07_23-53-47
\IQ_2022-04-07_23-53-47

150

Fri Apr 8 05:46:35 2022

V. Hannen

High background rate in Cu PMT points to light leak in ESR or active pressure gauge

The background rate of the Cu mirror PMT is only about 300 cps when the mirror is in the parking position but ca. 7000 cps when in the beam position, even if no beam is present in the ESR. This was noticed when we had an "empty injection" into the ring, causing the Cu mirror to drive into the beam position with no ions present.

This means either we have a light leak somewhere on the detector side of the ring, e.g. a not perfectly covered window, or we have a pressure gauge operating still to close by (during the LIBELLE experiment we turned off all pressure gauges on the detector side of the ESR not only in the straight section but also somewhat into the bends). This has to be checked the next time we can enter the ring.

149

Fri Apr 8 03:54:39 2022

Patrick

Q-switch window

The solution of increasing the Q-switch window from 2us to 5us described in ID:148 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.
This window "flickers". It gets very small, leaving no time for coincident events which fire the laser.
This is probably an issue with the NIM module.
Compare the picture below: The oscilloscope freezes and only the first of the yellow pulses is visible which should repeat and span 5us at the moment.

After looking at the different signals to trigger the laser on the oscilloscope, the laser does not fire anymore when used in the external trigger mode.
However, all signals are looking good and everything should be in the same state as before.
The internal Q-switch works as good as before.

148

Fri Apr 8 02:14:05 2022

Wilfried

Laser timings adjusted

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 both photodiode histograms move 3 bins further to the right (towards larger times till common stop, since the pulse arrives earlier).

Since the RF frequency is turned down from ~ 1 MHz to ~ 400 kHz during injection/preparation, the laser does not fire reliably and the beam stabilization does not work very well during this period. This was solved by increasing the window in which the Q-Switch signal is accepted from 2 microseconds to 5 microsececonds. The laser is now firing regularly and with high power also during the preparation time and the beam position stabilization works very well.

147

Fri Apr 8 01:48:57 2022

Patrick

Bugged Trending plots?

The wavelengths/frequencies shown in the graph in the labview window do not match the wavelengths/frequencies in go4.
Compare the picture which shows an incomplete laser scan although the scans in the labview window are completed (The measurement was started at an 'elapsed MBS time' of 2700s and took 1700s/28min).
However, the displayed time is correct. Only the data seems to be "stretched".

The same is true for the 'XUV anode' detector. The counter in the electronic module is ahead of the displayed count rate in go4.

Additional Note: The 'Cobra set wavelength' plot shows wavelengths which seem to be measured. However, we would expect deterministic setpoints from the software, see picture.

146

Fri Apr 8 01:18:51 2022

Ken Ueberholz

TODO: DAQ improvements

For somebody who knows the DAQ1 code: Go4 resets the histograms with each laser step. Can there be additional histograms where the data gets accumulated?

And possibly a histogram where important detectors are plotted against the laser steps? The read back wavelength of the wavemeter is not very precise.

145

Fri Apr 8 00:06:37 2022

Patrick

Connection to the laser pc

To login to the laser pc use the command

xfreerdp -g 1920x1080 -u atplaser atppc023.campus.gsi.de

144

Thu Apr 7 22:18:06 2022

Night shift 7.4-8.4

Next scans

DAQ1: lxg1927:/data.local2/BeamTimeTh22/
DAQ2: lxg0155:/data.local2/E142/
LMD file name DAQ1:229Thor
LMD file name DAQ2:229Th

Shottky and NTCAP started at 23:53, center freq. 242.2M, 10MIQs, -30dBm
Shottky marker pos: 243.973MHz

Time	SIS-intensity	cooler-HV	LMD-DAQ1	LMD-DAQ2	scan range(nm)	step width(nm)	dwell time(s)	comments
00:20	1.4e9	209617	0065-0067	7810	323.2-321.2	0.01	4	buggy DAQ? see Elog, file 0068 empty
01:27	1.6e9	209606	0069-0070	7811	323.2-321.2	0.01	4	buggy DAQ? see Elog, file 0071 empty
02:15	1.6e9	209611	0072-0073	7812	323.2-321.2	0.01	4	buggy DAQ? see Elog, file 0074-0075, 7813-7814 empty
03:00	1.1e9	?	0076-0077	7815	323.2-321.2	0.01	4	buggy DAQ? see Elog and below, file 0078, 7816 empty

We were searching for a difference of a factor of twoin both DAQs. It turns out that the default value for the MBSstream server task is scale=2. In the main task this value is explicately set to scale=1. we will now (starting with filenumber: 0078) restart the 2nd DAQ with set stream_serv scale=1.

Also TDC is disabled.
From file number 0076 in DAQ2 : ADC thresholds:
unsigned short caen_V785AH_threshold_mod0 [32] =
{0x0100 , 0x0005 , 0x0004 , 0x0003 , 0x0004 , 0x0003 , 0x0005 , 0x0003 ,
0x0005 , 0x0004 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 ,
0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 ,
0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 , 0x0100 };

Before the next scan, we realized, that the laser destabilized. For the rest of the shift we tried to get laser back online (see ID:149).

143

Thu Apr 7 19:13:26 2022

Konstantin, Patrick

Calibration

How to find the correct laser position

In order to achieve the correct laser ion beam superposition one needs to do the following steps:

If the laser stabilization is still running, turn both stages off and block the main amplifier.
Ensure that the laser spot is centered on the paper screen, which is located in top of the laser tower in the south (ATTENTION: please only use the preamplifier and not the main amplifier!!! If you're unsure what you are doing please contact Rodolfo or Konstantin).
If this is not the case and the beam is completely off, have a look at the MRC Stabilization system. If it is running, close the software and turn the hardware off and on again. The spot will leave its position and come back after the stabilization is turned on again.
If it is still not centered, use and only use the piezo mirror (the one with red screws) to bring back the spot.
Remove the paper screen and then turn on the main amplifier.
Restart the software and put in the values from the file 07-04-2022(...).png. Start the two stabilization stages in the software. The laser spot should move back to the correct position.

142

Thu Apr 7 16:50:22 2022

Konstantin

Calibration

Spacial laser-ion overlap

Laser-ion-beam overlap was achieved after measuring the ion beam positions (compare Entry 83).
Screenshots are comprised in the following table.

scraper	position	screenshot
GECEDS1HA	-8.6 mm	Laser beam scraped from the left
GECEDS1HA	-17.4 mm	Laser beam scraped from the right
GECEDS2HA	-13.4 mm	Laser beam scraped from the right
GECEDS2HA	-4.6 mm	Laser beam scraped from the left
GECEDS2VU	7.7 mm	Laser beam scraped from the top
GECEDS2VU	-1.3 mm	Laser beam scraped from the bottom
GECEDS1VU	-0.9 mm	Laser beam scraped from the bottom
GECEDS1VU	8.1 mm	Laser beam scraped from the top

141

Thu Apr 7 16:45:10 2022

Detector distances

Relativ distances of the detector

140

Thu Apr 7 15:18:25 2022

Danyal & Sebastian

DAQ channels

We checked again the cables for both DAQs 
(on Carsten's kind request) 


Channels for both DAQs are: 

0 XUV-Back 
1 XUV-Anode 
2 XUV-Anode-delayed 
3 PMT-South (new PMT, new threshold)
4 PMT-Middle 
5 PMT-North 
6 PMT-Cu 
7 Part-det-south 
8 Part-det-north 
9 - 
10 - 
11 - 
12 - 
13 PD-NO
14 PD-SO
15 Q-switch

139

Thu Apr 7 14:13:27 2022

Danyal

new PMT south

I have replaced the PMT south (looks at the gas target). 
in the hope that this will produce less dark counts. 
Thus far, the dark countrate is low (few Hz). 

brand: ET enterprises 
type:  2" photomultiplier, 9423B 
High voltage: -2.45 kV  (up to -3.5 kV) 
spectral range: 110 - 230 nm 

The power comes from an additional 2.5 kV supply. 
(I have changed the cable: was CH0 before)

138

Thu Apr 7 14:04:36 2022

Paul Indelicato

General

no beam until 17:00

10:10  There is a problem with the UNILAC. 
The repair will take several hours. (4 hrs?) 

14:00  We just enquired about the status and when beam could be back. 
The current estimate is 17:00.

More work on laser aligment is required. 
Estimated time: 1 hour

137

Thu Apr 7 14:01:22 2022

Sebastian, Max