Digital Hadron CalorimeterCosmic 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

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