ELOG CIRCE

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

CIRCE

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Entry time:	Fri Apr 6 13:33:27 2018
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<p>On 05/04/18, after eLog #28</p> <p>After the alpha calibrationrun Raffaele arrived and started beam tuning for 7Li 2+ at 5.0MeV using a LiO molecular source</p> <p>We set the target ladder to position II (80.024 mm) - no target frame or target</p> <p>Set downstream sperture to 82.5mm and central aperture to 85.5mm (iris diameter ~ 18mm)</p> <p>Raffaele was struggling with tuning on accelerator end of beamline - decided to perform a pulser walkthrough</p> <p>16:02 started DAQ for pulser walthrough, save name: 180405150720</p> <p>Voltages covered: (Pulser amplitude setting)</p> <ul> <li>1.4V</li> <li>1.2V</li> <li>1.0V</li> <li>0.8V</li> <li>0.6V</li> <li>0.4V</li> <li>0.2V</li> </ul> <p>Note: pulser is daisy chained between both S2 preamp boxes (NOT diode preamp)</p> <p>16:56 DAQ stopped, RT = 00:54:05, DT = 67%, Trigger Rate ~ 2kHz, Event mult = 53.1</p> <p>At 16:57 the pressures read:</p> <ul> <li>TPU1 = 6.2e-6 mBar</li> <li>TPU2 = 9.1e-7 mBar</li> <li>TPD1 = 1.7e-6 mBar</li> <li>TPD2 = 1.7e-6 mBar</li> <li>CHUP = 9.4e-6 mBar</li> <li>CHDW = 2.5e-5 mBar</li> </ul> <p>Checked detectors:</p> <ul> <li>Central S2 bias = -130.0V, leak I = 8.23 uA</li> <li>Diode bias = -70.1V, leak I = 0.00uA</li> <li>Downstream S2 bias = -130.1V, leak I = 2.44 uA</li> </ul> <p>We opened the line valve, with no beam DAQ reads: DT = 8%, Trigger rate ~ 3400 Hz, event mult = 52.9</p> <p>Beam tuning was performed with no target frame in the beam axis, beam voltage = 2.1358 MV</p> <p>We had 1.2nA in FC 4, we supplied -400V to FC-E0 (FC immediately before chamber) for electron suppression</p> <p>FC - 0 = 1.8nA (unsuppressed immediately after chamber)</p> <p>We moved the target ladder to position I (3mm collimator)</p> <p>FC-0 = 600pA</p> <p>We need to use the ERNA magnet to bend the bean into FC-45 located after the chamber, this faraday cup is suppressed</p> <p>CSSM magnet ON = 906.13mT, we noticed this section of the beamline needed pumping, switched on pump at 17:45</p> <p>Received email from Tom D regarding noise, he suggested a few checks:</p> <ul> <li>Try changing preamp - feedthrough cable (currently have one spare which is wrapped in Al foil instead of copper tape - not ideal)</li> <li>Feedthrough - preamp cable drain wire should be connected to PCB at one end and the other left floating (both are attached to PCB at this time)</li> <li>Try isolating feedthrough - preamp cable from preamp lid - it may be touching</li> </ul> <p>At 18:00 Raffaele needed to leave the lab, Jeremias could stay until 20:00, we decided to try and address the noise issue further</p> <p>I switched off the detectors and preamp power, I removed the downstream preamp box lid and disconnected one end of the feedthrough - preamp drain wire (the end where the first 32 channels are connected on the PCB - connector P1)</p> <p>I remounted the downstream preamp box lid.</p> <p>The DAQ shows DT = 8% with 3kHz trigger rate.</p> <p>To check the effect from the central S2, I tried setting the DAQ OR to only come from the central S2 and diode - I realised I could no longer see the pulser peak in the central S2 -> suggested central S2 trigger not working</p> <p>I changed the cable between the 3rd and 4th MALU 4532 modules and the respective ECL-NIM converter -> now see triggers -> DAQ gives DT = 51% and trigger rate ~ 5.6kHz, but see pulser peaks in ADC modules 5 and 6</p> <p>I considered only the downstream S2, setting pulser to 1.0V, RAL 1 CH1 amplifies this to ~5.5V with ~20mV noise.</p> <p>Setting the DAQ OR to only come from this detector, the DAQ DT = 10% and trigger rate = 10Hz, event mult = 133.2. So it seems making one of the drain wires loose had a big effect on the noise.I decided to make the same change for the central preamp.</p> <p>After switching off the detectors and preamp, I opened up the central preamp box and left one end of the drain wire on the preamp - feedthrough cable hangng loose. This is the same end as the one chosen for the downstream preamp.</p> <p>Leaving the central preamp lid off, I reapplied preamp power and rebiased the detectors</p> <ul> <li>central S2 bias = -130.0V, leak I = 8.10uA</li> <li>diode bias = -70.0V, leak I = 0.01uA</li> <li>downstream S2 bias = -130.1V, leak I = 2.27uA</li> </ul> <p>Checking RAL X CH1 (central S2) amplifiedoutput: 1.0V pulser output is amplified to ~5.5V with 50mV noise. Note the preamp box lid is off, so this looks promising.</p> <p>I set the DAQ OR trigger to come only from the central S2, DT = 91%, trigger rate ~ 7kHz. High rate seen in ADC 6 channels 1->7 and channel 31</p> <p>Changed DAQ OR to come from all 3 detectors, DAQ DT = 93% with trigger rate = 6700Hz, still see high rate in ADC6 channels 1-> 7 and channel 31</p> <p>The time was 20:00 so we stopped for the day, it looks like the downstream S2 electronics is working fine, will check effect of mounting central preamp lid back tomorrow</p> <p>All detector biases ramped down to 0V, preamp power off</p> Encoding: HTML ELCode plain Suppress Email notification Resubmit as new entry

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