Powered system up with 4 bare 45cm kaptons connected and nothing seems to have changed from where we left last night

Waveforms in nnaida11 look good and peak widths in nnaida11 1.8.L and 1.10.L are ~70ch.

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

no obvious change in peak widths for nnaida11

turned all back on by resetting value of offset 0x00 to 1

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.

1.4.W      -     mean:    8612.9            st. dev.:     20.5

1.6.W      -     mean:    8548.9            st. dev.:     16.6

1.8.W      -     mean:    8900.8            st. dev.:     16.2

1.10.W    -     mean:    8744.5            st. dev.:     15.0

Removed kapton to check intrinsic RMS deviation of pre-amp using the same method

1.4.W      -     mean:    8666.8            st. dev.:     4.7

1.6.W      -     mean:    8586.6            st. dev.:     2.0

1.8.W      -     mean:    8918.7            st. dev.:     3.2

1.10.W    -     mean:    8782.3            st. dev.:     4.2

These results are consistent with the pulser peak widths observed with/without Kapton PCBs attached

Make a makeshift screening plate for the adapter PCBs using the Cu tape -> widths in nnaida11 all slightly worse but still comparable.

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)

Initially observed very noisy waveforms but grounding adapter PCBs together improved the noise slightly but not to an acceptable level (see attachment 2+3).

Measure the peak width as a function of shaping time:

t_shape:             0.5   |   1.0   |   2.0   |   4.0   |   8.0

FWHM (ch):     308    |   352  |  345  |   252  |  130

Throughout, the peaks were non-Gaussian and double peaked with single peak widths ~50-70ch.

Pickup effect rather than white noise?

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).

Changed grounding around (adapters to NIM crate, adapters to detector box etc) and observed no noticeable difference.

However, removing jumpers grounding PCBs to FEE cards and the grounding between the adapter PCBs makes the noise worse.

Shielded 3 more 45cm kaptons and connected detector -> no leakage current.

Found several pins on 2 kaptons to be broken. Will get these fixed in Edinburgh for use next week.

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).