22:53

Run 15 started

Beam tests. We increased the storage time to 2min and switched to bunched beam so that we can see the beam lifetime over the cycle.

D+ Beam energy is set to 1.5 MeV.

Detectors are positioned in with servos only (left arm = 28.06mm, right arm = 29.23 mm)

No target

We observe a large peak at the start of the cycle at 750 keV. This seems to be molecular hydrogen circulating in the ring. We also see a much smaller peak at 1.5 MeV (D+)

After a period of time the 750 keV peak decreases significantly and we are left with the 1,5 MeV peak only. 

Total energy histogram after running for ~ 1 hour - attachment 1

Total xy plot after ~ 1 hour - attachment 2

We observe the large circular structure on the left hand detectors. Is this related to hydrogen or is it the beam type (bunched instead of coasting)?

In the GSI control plots for the number of ions in the ring we observe a large drop in ions circulating at the start of the cycle, and then remains fairly constant throughout the rest of the cycle. - attachment 3

This seems to confirm our hydrogen hypothesis.

23:54

Run 15 stopped, Run 16 started.

All setting the same and still no target, except beam is now coasting. We will compare to Run 15 after one hour of running.

We do not observe the circular distribution on the detector seen in the previous run. It seems this effect comes from the bunched beam. Reason?

We still observe the 750 keV peak at the start of the cycle.

Total energy histogram after running for ~ 1 hour - attachment 4

Total xy plot after ~ 1 hour - attachment 5

00:59

Run16 stopped. Run 17 started.

All settings the same except we have switched back to bunched beam.

Target now on. (X=-13700, Y=0). Target density ~ 1E11 at/cm2.

02:03

Run 17 continues

Target has increased in the average density to ~4e11 at/cm2, no changes made to nozzle position and fluctuates to 1e11 or 1e12 at/cm2.

Energy histograms and the xy plots appear similar to bunched beam with no target. The rates are slightly lower with the target for the left hand dssds, maybe target interactions destroy molecular hydrogen quicker?

Total energy histogram after running for ~ 1 hour - attachment 6

Total xy plot after ~ 1 hour - attachment 7

We will continue to run for another hour or so in this condition

Target density has decreased over the last minutes. We have tried to move the nozzle to maximise density but fluctuations make this difficult.

03:55

Increase in ADC data items statistics for aida 13 and 14 from ~20 kHz to 90 kHz

ASIC checkload has reduced the rates back to ~ 20 kHz

Total energy histogram after running for ~ 3 hour - attachment 8

Total xy plot after ~ 3 hour - attachment 9

Run 17 stopped. Run 18 started

Beam changed back to coasting. All other settings unchanged. Target on. 

04:55

Run 18 continues.

Energy histograms and the xy plots appear similar to bunched beam with no target. The rates are lower with the target than without.

Total energy histogram after running for ~ 1 hour - attachment 10

Total xy plot after ~ 1 hour - attachment 11

Note we observed fluctuations in the T2 temperature for the target. T2 is set to 80 K but rapid fluctuations were observed up to 100K. This occurred for only 5 minutes and I am not sure if it is a real effect.

07:20

Temperatures OK

System wide checks OK

Rates OK

Stats OK

Waveforms attached

Leakage current decreasing slightly.

No changes to beam or target.