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| Nuclear hyperfine mixing in 229Th89+ 2024 |
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Message ID: 19
Entry time: Wed Jun 5 19:22:43 2024
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| Author: |
Carsten, Konstantin, Rodolfo |
| Category: |
Detectors |
| Subject: |
PMT tests and preliminary thresholds |
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For all channels of the CAEN CFD the width of the logic signal is set to 255ns (maximum) to mitigate potential double pulses. For the very low count rates of the experiment this is not problem.
Tested and (partially) set-up UV PMTs and Chenneltron with a UV LED.
- The UV LED does not give a useful signal for the small-band VUV PMTs.
- In general, (using the new cables?) it seems that the cable noise is very low and can be easily discriminated.
- PMT south (the broadband) sees a regular "strong" pulse-train/burst of photon signals. Therefore, the PMT was exchanged against a different one (SolarBlind ET Enterprises Model 9422, SN1042) - same result. New data sheet is attached.
- The channeltron has a rather broad pulse height distribution but very low background. CFD thresholds can easily be set. Very likely the best detector to adjust the laser timing?
- Channeltron Head : -2.5 kV , CFD threshold 8 mV.
- PD SO threshold needs to be checked (in Go4 the number of counts of PD SO is much lower than of PD NO). Present values: both 10 mV.
- Voltage PMT north / middle (both small-band) : -2600V, PMT south (replacement): -1500V. All thresholds: 15 mV
- CAEN CFD must be switched back to LOCK or it otherwise produces additional background
Both DAQs run with about 2 laser scan cycles, 201 steps. 90 shots each...
date written to files.
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