09:10

Arrived at GSI. Leakage currents status same as before, DSSD4 is still fluctuating. DSSD1 and DSSD3 currents are definitely lower again compared to previous days. I am convinced they are decreasing over time, whether this will be enough for our measurement....

While in the cave I again removed the motors pins so that the detectors can can be shook in an attempt to perform magic. While in the cave I also connected the CRYRING ground cable to the coolant pipe (ground config 11). Will see effect on rates / pulser.

Ground config 11 - see attachments 1-8. Rates in aida03 are massively down by a factor 10! Rates now ~20k. Aida04 still around 300k. On attachment 4 we can see the noise from zero energy on aida03 is massively down and we can now see the pulser, although the peak is double. Similar low energy noise is now appearing on aida15 and aida16 of DSSD4. Is this the early phase of what happended to DSSD1 and DSSD3?

Note the waveforms shown in attachments 7 and 8 change quite alot when updating the spectrum browser. Wave structure very visible in 7 but after updating a few times this disappears before coming back again a bit later.

20 minutes later ...

DAQ continued for about 20 minutes, noticed the leakage current in DSSD4 was no longer fluctuating. Zero'd stats and histograms to look again.

Stats in aida03 have increased back to ~100k, still less than before but back up from ~20k. Check of the pulser widths shows they have decreased across the board from the previous test 20 mins ago.

Leaving DAQ to run for a bit longer, the rates in aida03 continue to increase and are now back ~200k (back where it was).

I am currently trying to cycle motors. No effect on leakage current when cycling pneumatic motor. Note when using single commands such as 'l p in' I have no problems. But when trying a longer command where I ask the code to wait before pulling the pneumatic out again the code crashes. ??? Crash not repeated by Carlo remotely, Perhaps it is my laptop, or a bug relating to windows. Will investigate back in Edinburgh.

Have performed the same bias test for DDSD4 as #1 and #2 in previous elogs. Same behaviour observed. No (0.01uA) leakage current with only nn and current ramps up and falls to zero with only pn. I did notice that the ion pumps were arcing, I have not noticed this in prevous days. They have now been turned off, I think we can leave them off as they do little for the vacuum anyway unless using heavy gas taget gas. VI bias curve looks identical to one performed at the start of the week.

I have moved the PC power to the 19 inch rack. Power cycled the FEEs. I noticed the leakage current on DSSD4 was fine during VI test but after starting the FEEs power cycle they started to fluctuate again. After about 5 minutes after the startup, DSSD4 leakage current returned to a normal stable level. I have seen spikes in leakage current for all detectors during power cycle but perhaps it could also cause the fluctuations in #4. Overnight I have left FEEs off due to uncertainty over the swagelock on aida08 and the fact I was changing ground a lot so a background didn't make sense. Perhaps leaving FEE power on will stabilise DSSD4? I will leave system to stabilise a bit now (after seeing rates and pulser widths change in previosu test) and check pulser widths. Going for an awful GSI coffee.

New configuration: See attachments 9-13. Rates on aida03 and aida04 still remain very high >200k. Pulser widths across the board look pretty good. All have reduced since moving the PC on same power supply as 19 inch rack. DSSD4 leakage current has been stable the last hour since FEE power on. Waveforms look improved too. No longer see such high amplitude oscillations. Updated several times, see no change in waveforms like previous test.

Attachment 14 for pulser widrths from tests this week. Note x means no value. This could be because the width was so very big, or the test input wasn't connected. These values aren't too bad. DSSD2 and 3 have avergae pulser width (1.8L only) of ~60 keV.

Tried ground cable to NIM bin, had no effect / maybe negative effect. Disconnected cable.

D+D tests in next elog

Finally a pulser walkthrough was completed. Run8 has pulser settings unchanged, slow comparator at 0x64, aida03 and aida04 set to MEC. Pulser amplitudes 9000,8000,7000,6000,5000,4000,3000,2000,1000

A second walkthrough (Run9) was done with slow comparator set to 0x14, aida03 and aida04 set to MEC. Pulser amplitudes 9000,8000,7000,6000,5000,4000,3000,2000,1000,700,400 (so that we can check ~BBN energies) - attachment 15

During second walkthrough, DSSD4 starting fluctuating in leakage current again. No-one was in the ring. No observable change. FEEs were ON and were currently acquiring. ?? See noise which in attachment 15 on aida15/16 that only started when current was fluctuating.

FEEs off. Bias on and monitoring. Pins re-inserted into motors. Compressed air off.