Digital Hadron Calorimeter Cosmic Ray Test Stand

Status Multichannel system is working Good data on 12 channels but 2 channels very low gain Switched to unused channels over the weekend don't know results yet 1 other channel has fiber damaged Lightning caused computer to reset need to get UPS Changed software to save data every hour

Analysis Software Wrote my own software using Visual Basic to display data Can display by data by cell or by PMT channel Can switch between top layer and bottom layer of cells Show small histogram bin=5 Show large histogram bin=1 Primitive method of finding pedestal, pedestal cutoff, first peak cutoff Scatter plots of all data, data above pedestal cutoff, data above first peak cutoff

Summary of Results 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 PMT covered by black paper and only get narrow pedestal Crosstalk can be –optical crosstalk in cells –electrical crosstalk in PMT Way to be sure if electrical crosstalk is to use LED to stimulate one channel and study the effects on nearby channels First curve goes away when PMT HV is reduced from 1000V to 800V If first peak is single electron then light yield ~ 12 photoelectrons

Scatter Plots Also have scatter plots Can set the channel for the X-axis and then select top and bottom layers separately For example using Channel 4...

Ch4 vs No pedestal

No pedestal and no first curve

Next Steps Look at data from weekend with unused channels Stimulate PMT channel with PMT to determine electrical cross talk Enhance software Collect data with absorber