14/04/25
Arrived at GSI in the afternoon.
Found that the coolant loop on aida08 had popped out which resulted in the high FEE temperatures observed (see attachment 1). Female swagelock connector on FEE suggested to be the cause as this connector has the locking mechanism. FEE dismounted and female swagelock connector removed. No obvious defect in the connector (see attachment 2).
Turning on detectors we observe ~4uA in DSSD2 and DSSD4 (right hand side detectors) and ~15uA in DSSD1 and DSSD3 (left detectors). Leakage currents in left hand side detectors is down from ~17uA seen at the end of last week and ~19uA at start of last week. Temperatures in the cave do not appear to have changed sufficiently to explain this change. VI curve completed to test diode response (attachment 3+4).
Motors turned on to again see if it changes the leakage currents in any way. Both arms homed. Left arm moved in with pneumatic and servo (10mm). No change in leakage currents during movement or when fully in. Same procedure with the right arm. No change in leakage currents in either. I doubt this is a light affect. If some light was incident on the left hand detectors, moving the detectors should have changed the amount of light on them in some way, reducing the leakage current. Similarly if light can hit the detector when fully in for the left arm, some should be hitting the right arm when it is fully in too, but no change observed on the right arm either. No light sources found on interaction chamber, baking jackets covers all ports.
Movement for several repeptitions with the pneumatic tried to see if this had any affect -> no change
Bias lines for DSSD1 and DSSD2 swapped around on the caen bias module. No change in leakage current for DSSD1 or 2. Channel on bias module not to blame.
Tried turning ion pumps off, no change on leakage currents.
Tried reverse biasing the detectors. Polarity for channels 0 (DSSD1) and 2 (DSSD3) swapped from -ve to +ve on bias module. Core and braid swapped on adaptor card. Completed VI curve when reverse biased for these detectrors. Obtain the same curve as with -ve polarity. Left at 100V for 10-15 minutes. Put polarities back to -ve, no change in leakage currents observed.
Opended up one of the diamond windows with bias off. Shone my phone light through the window for ~30 seconds. Closed window off again, biased, no change observed. Left detectors biased overnight. CH0 - 15.4 uA, CH2-14.7uA.
15/04/25
No change in leakage currents overnight. From gnuplot they look pretty flat overnight. Perhaps slight decrease.
Checked attaching LK2 jumper to aida09 (nn DSSD3). Could not reach other nn adaptor card. No effect on leakage current. Dismounted jumper.
New female connector mounted on aida08 and FEE remounted.
Restarted AIDA system by closing all windows and servers. Error on starup, could not connect to relay16 for FEE power.
Issue related to dew point interlock. Dew point sensor is very sensitive and any movement can cause it to trip. Sensor was not well supported on the coolant pipe. Sensor remounted with plastic zip ties. Issue resolved. Investigate some noise issues in the afternoon
After lunch I have noticed the leakage current have increased slightly. See attachment 5. CH3 is higher and appears to be fluctuating by 1-2uA. Turning off bias and going to cave to investigate.
Bias still higher and fluctating on CH3. Konstantin is in the ring, but he has not started any works yet, some grossmontage are also in the ring and are working on the new source. Could this be affecting us? Either way, will startup daq to check rates/noise etc.
Previous settings applied (i.e all channels back to LEC). Have lost the dew point interlock again!
I have suspended the dew point sensor in the air for the time being -> need to put a dummy in.
Grossmontage working on ion source have left and leakage current on DSSD3 is no longer fluctuating -> coincidence? (attachment 6)
AIDA started again. Rates appear OK except for on 3,4 and 15. (see attachement 7,8,9) Note the rates on 9,10 are reduced compared to previous elog entry. Note pulser off. Note on aida startup aida16 clock status fail and ADC calibration fail for aida 6,14 and 16
16:00
We again see DSSD3 leakage current fluctuating. I will head back to the cave to check if anyone is working again? Nikos and davide working on the target but can't see how they would impact the leakage current (they were only installing a support for the new turbo)
DSSD3 remains fluctuating even now they have stopped working.
Pulser on. Same settings as elog 664 -> freq = 10 Hz
Overall pulser widths look bad, rates (ADC data items) look okay (~1000) for all except aida03 and aida04 (>250,000). Again rates on aida09 and aida10 are good although the widths are poor. One change I did make was to ground the FEEs to the CRYRING ground wheras previously they were grounded to the coolant pipe. I may try putting them back onto the coolant loop to see if there are any changes. Note grounds all around have not been examined yet. Attachments 10-17 with pulser on.
Moved grounds back onto the coolant pipe -> no effect on ADC rates.
Also tried lowing slow comparator theshold down to 150 keV (0xf) for most channels (except aida3 and 4). See rates attachment 18.
FEE power off, bias remains on
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