Cosmic%20Ray%20Test%20Stand%20with%20Scintillating%20Cells%20for%20Digital%20Hadron%20Calorimeter

1
Cosmic Ray Test Stand with Scintillating Cells
for Digital Hadron Calorimeter
As of 9am 05/19/2003
2
Summary of Initial Results

• It is a primitive tracking calorimeter
• Most show two peaks one of them is close to
  pedestal
• Is first peak single photoelectron, crosstalk, or
  noise?
• Not noise because I took samples with all all
  photocathodes of PMT covered by black paper and
  only get narrow pedestal
• Crosstalk can be
• optical crosstalk in cells
• optical or electrical crosstalk in PMT

3
Status

• Most of what I did over past week was to
  determine what the first peak was
• Collected cosmic ray data because it is closer to
  real application than to use LED and because
  single fiber from LED is to weak
• Small part of cross talk is optical crosstalk
  between cells
• I was able to reduce it by isolating all cells in
  top layer with black paper
• Larger part of crosstalk is at PMT

4
First Peak Single Photoelectron or Crosstalk?
5
Cell 4 isolated from 3/6 adjacent cells covered
by black paper Channel 4 isolated from all other
channels
6
Cell 4 isolated from all adjacent cells Channel 4
isolated from all other channels
7
Channel 4 stimulated by several fibers driven by
LED
Suggests crosstalk at PMT
8
Cosmic ray data, Cell 4 isolated from all
adjacent cells Channel 4 isolated from all other
channels
9
Crosstalk at PMT

• Id like to quantify crosstalk of channel A into
  channel B
• Want to find way of relating number of events in
  second peak of a channel with number of events in
  first peak of all nearby channels
• Events in first peak of channel B / Events in
  second peak of channel A
• In this case I used Channel A 4
• Events in second peak of Channel 4 366
• Events of first peak in Channel 3 45

10
Map of Crosstalk effects of channel 4

• Ratio of events in first peak of a channel over
  single peak of channel 4
• 0/366 0/366 1/366 1/366
• 4/366 1/366 0/366 0/366
• 45/366 13/366 1/366 2/366
• n/a 84/366 7/366 1/366
• Percentage of single peak
• 0.0 0.0 0.3 0.3
• 1.1 0.3 0.0 0.0
• 12.3 3.6 0.3 0.5
• n/a 23.0 1.9 0.3

11
Summary

• Should measure every channels effect on every
  other channel but dont have time
• Would like to at least do with one of the 4 inner
  channels, for example channel 7
• It appears that the strongest crosstalk is only
  on adjacent channels
• Optical crosstalk at cells can be reduced by
  isolating cells with black paper