On the 18th of September we installed DSSD 3208-14

Was found to have problems including exponential leakage behavior

  V      Ic
 -5   15.4uA
 -10  53uA
 -15  Tripped at over 100uA

Cables were double checked, bond wires were checked and no problems could be observed.

DSSD replaced with 3208-15

Bias at -100V Ic 10.2uA GP/grnd Jumpers removed,
                         rising upwards, possible short circuit as well.

Jumpers replaced

Bias -100V Ic 1.6uA
Bias -160V Ic 1.62uA

Possibility that mechanical sample 3208-17 and 3208-14 have been swapped. (To check at later date)

FEEs powered up and Adapter boards and all grounding installed with DSSD going to 9,10,11 and 12

Rates shown - attachment 1
Waveforms - attachment 2-4
1.8.l Spectra - attachment 5
FEEs 10 and 11 around 60FWHM and 9 and 12 around 80-90FWHM
Stats page - attachment 6

Aluminium foil used to make sure all ports are light tight shows a stats drop of around half - attachment 8

New peak widths

aida09 - 79.65
aida10 - 67.37
aida11 - 59.99
aida12 - 97.83

Going to begin a systematic study of shaping time

                              FWHM
Shaping Time   aida09   aida10   aida11   aida12
   
     8          79.65   67.37    59.99     97.83
     7          97.55   70.84    62.67     115.34
     6         100.72   70.04    62.77     120.05
     4         147.47   80.64    71.34     167.23
     2         217.62   114.98   133.35    232.47

Shaping time 8us 1.8.L Shots 
Shaping time 4us Stats appear obviously worse - attachment 7
                 1.8.L Widths - attachment 8
Shaping time 2us Stats appear worse again - attachment 9
                 1.8.L Widths - attachment 10
Shaping time 6us Stats are better than 2 and 4 - attachment 11
                 1.8.L widths - attachment 12
Shaping time 7us Stats are better than 6 - attachment 13
                 1.8.L widths - attachment 14


8us is the optimum shaping time.
Taken back to 8us and similar shaping times are observed.

Connected the ground of all 4 adapter boards with direct cables. Observed improvements in both FEEs 9 and 12
however the noise in 11 went
through the roof >500kHz - attachment 15

Tested just having 9,10 and 12 connected the rates are comparable to when disconnected - attachment 16

All 4 grounded together with a ground running to the snout as well stats No difference to all 4 together -
attachment 17
              1.8.L Widths - attachment 17
aida09 104.76
aida10 84.58
aida11 281.77
aida12 82.58

Tested just having 10 and 12 directly connected. Same side of the DSSD: Noise is the same as when disconnected.
Stats - attachment 19
1.8.L spectra - attachment 20

aida09 107.13
aida10 67.02
aida11 66.78
aida12 131.51

Tested having 11 and 12 connected directly. This is the two adapter boards responsible for the bias with 11
carrying the core and 12 the braid.
Massively reduced noise in 9 and 12, comparable noise in 10 but much more noise in 11. Stats - attachment 21
aida09 63.96
aida10 76.64
aida11 125.96
aida12 68.05
1.8.L spectra - attachment 23



18:39 Alpha run started in /TapeData/Sep18/R2
      Writing at 96kb/s
      11 Was fast at start bus asic control brought it down