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| Nuclear hyperfine mixing in 229Th89+ |
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Message ID: 150
Entry time: Fri Apr 8 05:46:35 2022
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| Author: |
V. Hannen |
| Category: |
Detectors |
| Subject: |
High background rate in Cu PMT points to light leak in ESR or active pressure gauge |
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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. |