Noise in clao

1
Noise, SCAs, etc (III)
Robert ZitounTuesday meetingNovembeer 4,
2002Stony Brook and LAPP
2
Noise distribution

• Pedestal run 164363 (official noise gain 8 run)
• How much from calorimeter, preamplifiers,
  SCA/BLS/ADC?
• Take a preamp off run

3
SCA/BLS/ADC contribution

• Pedestal run preamps off (165300)
• Not the same trigger 165300 commisioning/cal/ze
  ro_bias
• 164363 official/zero_bias
• Not the same SCA cell distribution

4
SCA/BLS/ADC contribution

• First single channel
• 9240 (typical) ih -2 i? 17 layer 1
• Compute pedestal for various fixed items
• Noise L1 dispersion ? updown asymmetry ? L2
  slope ? intrinsic
• 1.18 1.0 ? 0.19
  ? 0.26 ? 0.57

5
L1 dispersion

• Same in a L1 chip
• up/down are different
• similarity within a daughter card
• geometric correlation?

6
L1 dispersion (II)

• Dependence on the electronic location

7
up-down asymmetry

• some channels with large asymmetry. Traced to
  slow chips
• several channels fixed in the past (capacitance
  on daughter card)
• some more to do

8
L2 slope

• Slopes not that big
• Dispersion around the slope can be large
• Some cells may be way out of the slope
• Many SCA already changed. Some more to do

dispersion auroun slope
distance to slope
9
Intrinsic noise

• Double (triple bump) structure

10
Noise in towers
preamps on
preamps off
EMHAD1 all