18/01/16
Set up as last week but with 8us shaping time.
With detector connected, still seeing rail-to-rail noise on waveforms in nnaida13 and double peaking in all nnaida.
Measured various resistances around the system to gauge quality of grounding connections (all measured in Ohms).
- NIM crate to PCB LEMO connector: 4.8
- NIM crate to mezzanine Cu block: 5.3 -> Plastic guide pins now installed.
- Between LEMO connectors on the adapter boards: 0.19
- nnaida11/12 drain wire to nnaida13/14 drain wire: 0.25
- RH coupler nnaida13 to RH coupler nnaida11: 1.4
- LEMO to ribbon shielding nnaida13: 0.2
- LEMO to RH coupler shielding nnaida13: 0.4
Double peaking not seen in RIKEN or by PCS during his tests -> most likely pickup of external noise.
Connected multiple different cable types to see effect they have on the sinusoidal wave seen in the waveforms and on the double peaking.
- nnaida11: LH coupler (not shielded) + 45cm ribbon (shielded) + RH coupler (shielded)
- nnaida12: LH coupler (not shielded) + 45cm ribbon (shielded)
- nnaida13: old style 90cm kapton (19/02/14 revision)
- nnaida14: 45cm thin kapton (shielded) with foil over loose end
Setting as last week, with 2us shaping time.
Peak -to-peak differences in all nnaida for several channels:
| nnaida11 | nnaida12 | nnaida13 | nnaida14
1.4.L | 157 | 123 | 160 | single peak of width ~400ch
1.6.L | 119 | 111 | 170 | " "
1.8.L | 72 | Flat top single peak, width ~35 | 155 | " "
1.10.L | 90 | " " 42 | 177 | " " -> Noticed after cable gnd jumper was not connected on nnaida14 and needs to be for these kaptons. Explains v. large peak width. (Attachments 3-5)
19/01/16
Swapped cables on nnaida11 and nnaida13. Now have:
- nnaida11: old style 90cm kapton (19/02/14 revision)
- nnaida12: LH coupler (not shielded) + 45cm ribbon (shielded)
- nnaida13: LH coupler (not shielded) + 45cm ribbon (shielded) + RH coupler (shielded)
- nnaida14: 45cm thin kapton (shielded) with foil over loose end
In nnaida13 see ripple on baseline of waveform with period ~30ch = 600ns (@20ns per ch) => frequency of 1.67 MHz. (Attachment 6+7)
Resistance between drain wire end and ribbon shielding on nnaida13 cabele: ~0.8 Ohms.
" " RH coupler shielding on nnaida13: ~1.1 Ohms.
For shielded ribbon cable on nnaida13, see fairly flat waveforms. High frequency transients pass through, but no sign of sinusoidal wave over time window of 6us. (Attachment 9)
After swapping cables on nnaida11 and nnaida13 (only change to system), now see single, Gaussian peaks in nnaida12 with widths ~40ch.
For nnaida12:
Shaping time (us) | Avg peak width (ch) (avg of 1.8/9/10/11.L peak widths)
0.5 | 35
1.0 | 39 (1.11 width ~50ch, all others ~37-42)
2.0 | 39 ( " " )
4.0 | 35 (1.11 width ~45ch, all others ~32-38)
8.0 | 37
At 8us shaping time: in nnaida11 (old style cable), see single pulser peak of width ~150 ch.
nnaida13, still see double peaking with peak separation of ~90ch and an extra structure, like a small shoulder, on the outside of the peaks. (Attachments 8+10)
nnaida14, not fully double peaked, more a peak with a shoulder ~40ch apart.
At 2us shaping time: in nnaida11, pusler peak width back to ~300ch.
nnaida13, retains extra structure on outside of peaks, but peak searation increased to ~150ch.
nnaida14, double peaked, with peak separation of ~65ch.
(Attachments 11-15)
Cannot see waveforms on nnaida12, so swapped cables with nnaida11. Also acts as test of whether the good performance seen in nnaida12 follows the cables or is something to do with the FEE.
Now have:
- nnaida11: LH coupler (not shielded) + 45cm ribbon (shielded)
- nnaida12: old style 90cm kapton (19/02/14 revision)
Now see some Gaussian peaks in nnaida11 with width of ~60ch @2us shaping time, however some peaks seem to have a slight shoulder.
> suggests issue causing double-peaking is still present (and likely was in nnaida12), but is more/less apparent in some channels than others.
Questions:
** Is this just a very well shielded cable, or something to do with the intrinsic properties of this specific cable?
** What happens if a RH coupler is added?
** What happens if the RH coupler is removed from the cable connected to nnaida13?
Added RH coupler to cable on nnaida11.
Measured some resistances of the shielding on the nnaida11 (good performance - single peaks) cable and the nnaida13 (double peaks) cable:
- drain wire to far end of shielding: nnaida11 = 0.2 Ohms nnaida13 = 0.2 Ohms
- drain wire to RH coupler: nnaida11 = 0.4 Ohms nnaida13 = 0.5 Ohms
- far end of nnaida11 cable shielding to far end of nnaida13 cable shielding: 0.05 Ohms (this seems wrong considering pushing the multimeter probes together gets 0.14 Ohms, but was repeated several times and was always 0.05 Ohms)
With addition of RH coupler to nnaida11 (and shaping time still at 2us): (Attachments 16+17)
- nnaida11 peaks show slight shoulder and increased width of ~110ch.
- nnaida12 now sees noise over full-scale range
- nnaida13 now quad peaked.
- nnaida14 still double peaked, but peak separation increased to ~150ch.
Removed RH coupler from nnaida11, all peaks go back to how they were previously, before its addition (Something is repeatable - excellent!)
- some peaks in nnaida11 now non-Gaussian nad with widths ~130ch. Most Gaussian and width ~50ch.
Removed RH coupler from nnaida13:
- no real change in the spectra of any nnaida -> what is the difference between the cables on nnaida11/13???
Stock take of ribbon cables currently at DL:
- 90cm = 16
- 45cm = 16 (4 with me for testing in Edinburgh this week. Will be returned to DL next week)
- LH couplers = 10 (2 with me for testing in Edinburgh this week. Will be returned to DL next week)
- RH couplers = 10 (2 with me for testing in Edinburgh this week. Will be returned to DL next week)
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