AIDA
GELINA
BRIKEN
nToF
CRIB
ISOLDE
CIRCE
nTOFCapture
DESPEC
DTAS
EDI_PSA
179Ta
CARME
StellarModelling
DCF
K40
AIDA
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Entry time:
Sat Nov 14 20:19:43 2015
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<p> <table width="98%" align="center" cellspacing="1" style="border:1px solid #486090;"> <tbody> <tr> <td cellpadding="3px" style="background-color:#486090; font-weidht:bold; color:white;">Quote:</td> </tr> <tr> <td cellpadding="10px" style="background-color:#FFFFB0;"> <p>Powered system up with 4 bare 45cm kaptons connected and nothing seems to have changed from where we left last night</p> <p style="margin-left: 40px;">Waveforms in nnaida11 look good and peak widths in nnaida11 1.8.L and 1.10.L are ~70ch.</p> <p>Turned off flash ADCs for all FEEs by setting Q8_transfer.vhd: 0xa00, offset 0x00, to 0 to assess any affect they may play in the observed noise</p> <p style="margin-left: 40px;">no obvious change in peak widths for nnaida11</p> <p style="margin-left: 40px;">turned all back on by resetting value of offset 0x00 to 1</p> <p>Measured RMS deviation of waveform baseline for nnaida11 with 45cm unshielded kapton connected by sampling waveform every 10 samples over 100 samples, i.e. every 200ns for 2us.</p> <p style="margin-left: 40px;">1.4.W - mean: 8612.9 st. dev.: 20.5</p> <p style="margin-left: 40px;">1.6.W - mean: 8548.9 st. dev.: 16.6</p> <p style="margin-left: 40px;">1.8.W - mean: 8900.8 st. dev.: 16.2</p> <p style="margin-left: 40px;">1.10.W - mean: 8744.5 st. dev.: 15.0</p> <p>Removed kapton to check intrinsic RMS deviation of pre-amp using the same method</p> <p style="margin-left: 40px;">1.4.W - mean: 8666.8 st. dev.: 4.7</p> <p style="margin-left: 40px;">1.6.W - mean: 8586.6 st. dev.: 2.0</p> <p style="margin-left: 40px;">1.8.W - mean: 8918.7 st. dev.: 3.2</p> <p style="margin-left: 40px;">1.10.W - mean: 8782.3 st. dev.: 4.2</p> <p style="margin-left: 40px;">These results are consistent with the pulser peak widths observed with/without Kapton PCBs attached</p> <p>Make a makeshift screening plate for the adapter PCBs using the Cu tape -> widths in nnaida11 all slightly worse but still comparable.</p> <p>Connected detector using 4 45cm kaptons (gnd via nnaida13) and baised via nnaida12+13 to +200V with a leakage current of 5.16uA (Room temp 24.2oC)</p> <p style="margin-left: 40px;">Initially observed very noisy waveforms but grounding adapter PCBs together improved the noise slightly but not to an acceptable level (see attachment 2+3).</p> <p>Measure the peak width as a function of shaping time:</p> <p style="margin-left: 40px;">t_shape: 0.5 | 1.0 | 2.0 | 4.0 | 8.0</p> <p style="margin-left: 40px;">FWHM (ch): 308 | 352 | 345 | 252 | 130</p> <p style="margin-left: 40px;">Throughout, the peaks were non-Gaussian and double peaked with single peak widths ~50-70ch.</p> <p style="margin-left: 40px;">Pickup effect rather than white noise?</p> <p>Shielded kapton to nnaida11 with Cu tape and found noise to decrease slightly when grounded to LEMO connector on adapter PCB - bursts reduced in amplitude but persistent periodic noise remained (see attachments 4+5).</p> <p>Changed grounding around (adapters to NIM crate, adapters to detector box etc) and observed no noticeable difference.</p> <p>However, removing jumpers grounding PCBs to FEE cards and the grounding between the adapter PCBs makes the noise worse.</p> <p>Shielded 3 more 45cm kaptons and connected detector -> no leakage current.</p> <p style="margin-left: 40px;">Found several pins on 2 kaptons to be broken. Will get these fixed in Edinburgh for use next week.</p> <p>Reconnected old kaptons and system is as expected - slower rise time in waveforms but reasonable levels of noise and expected peak widths (see attachment 6).</p> </td> </tr> </tbody> </table> </p> <p> To power down the ADCs the register to be loaded with 0xFF is in the "Local Registers" window. </p> <p>What you did was to disable the readout of the ADCs which doesn't change the level of activity or reduce the power.</p> <p> </p>
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