ELOG AIDA

AIDA GELINA BRIKEN nToF CRIB ISOLDE CIRCE nTOFCapture DESPEC DTAS EDI_PSA 179Ta CARME StellarModelling DCF K40

AIDA

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Thu Nov 26 16:32:52 2015

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Powered on system without issue. biased detector to -200V. Leakage current not stable, bouncing around between ~3.66 - 3.74uA. Room temp 22.0oC&nbsp;&nbsp;&nbsp; -&gt; Peak widths similar to yesterday.
Changed through various permutations of jumper connections (field planes, detector grounds, bias ground reference).
The only change that led to any change in performance was the removal of the bias ground reference jumper, this made the waveform noise much worse and increased peak widths (attachment 4).
Changed the network cables to unshielded (no ground connection) ones. No difference in performance.
Connecting thick Cu braid from NIM bin chasis to LEMO connectors makes noise worse.
Moving this braid to the PSU case made peak widths larger and waveform noise in nnaida14 much worse. Traces do not return to baseline after a pulser event (attachment 2+3)
Reduced bias to -100V in an attempt to stabilise the jumpy leakage current -&gt; made it worse.
Increased to -250V and the leakage current stability improved -&gt; fluctuations of &lt; 0.10uA @ 4.985uA.
Connected Al detector box with thick braid to braid connecting HV and pulser input -&gt; no difference.
Replaced metal detector box with cardboard box so it was floating -&gt; no difference.
Made sure kaptons were all separated with sheets of paper to prevent electrical contact of shielding -&gt; no difference.
Disconnected detector and found double-peaking remains =&gt; this is not a detector issue, but intrinsic to the kaptons (with the kaptons removed, we observe Gaussian peaks of width ~14ch) (attachments 5-9).
Occasionally, waveforms fail to reset correctly (attachment 7).
Cu mezzanine block and Al crate now no longer isolated from each other. Resistance between them ~6 Ohms with crate locked up, increases to ~300kOhms when crate opened.

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