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 I’d 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 –0/3660/366 1/366 1/366 –4/366 1/366 0/366 0/366 –45/366 13/366 1/366 2/366 –n/a84/366 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/a23.0%1.9%0.3%

11. Summary Should measure every channel’s effect on every other channel but don’t 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