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| Nuclear hyperfine mixing in 229Th89+ 2024 |
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Message ID: 47
Entry time: Wed Jun 12 09:17:43 2024
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| Author: |
Carsten |
| Category: |
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| Subject: |
Tests of background with ionization pumps on (from monday) |
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On monday the ionization pumps were switch on to test the background, and if it is possible to run with the pumps switched on.
Results and comments, see below:
Later some data were recorded with DAQ1 to allow for a more thorough analysis - beam is 238U38+ at 401 MeV/u - file 0013
Please note the data of this file was recorded after the figures below were taken.
In short, we have switched off the the ionization pumps because the conclusion is somehow ambiguous. Background rates from real photons are considerably low at ~5Hz and 10Hz for the small-band PMTs (see figure), Yet, PMT south goes up to 350 Hz and sees a lot of photons from the plasma discharge. The few Hz of the small-band detector would be suppressed by the length of the ion bunch / full lenght of the ring. But what is not known is how much it would actually influence the local vacuum of the ring.
Semjon Strohmenger also checked that the valve to the turbos in front and behind the gas-jet is open (--yes). They are running the whole beam time.
I exchanged the prepump at a pocket located between gas-jet and VUV detection set-up. Here after baking a leak was found, and the pocket was pumped with an "old" prepump.
Vacumm in the pocket was ~1mBar. Installed a more powerful Edwards XDS i10. When we left ESR the pressure in the pocket was already at low 10^-2 mbar and still decreasing.
May be this helps to improve local pressure. |
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