June,18,2007 Teachers in lab

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  1. Jenette Briggs
  2. Keith Quigley
  3. Bettie Keetch
  4. Tony Forest

Monday, June 18, 2007

Out Quarknet Teachers had their first seesion experimenting with a coscmic ray test stand made up of two scintillators. Each scintillator was attached to a single PMT. A voltage of -900 Volts was applied and signals were observed using an oscilloscope.

First Cosmic ray scope pictures using PMT + Scintillator

First scope picture on a single detector


now look for a coincidence signal between two PMT detectors


Tuesday , June 19, 2007

Today our team of experimenters setup a discriminator (LeCroy Model 821) to determine which of the PMT outputs would be used to define the presence of a charged particle passing through the scintillator. The discriminator takes a signal from the PMT that is above the threshold (-30mV to -9V)and returns a voltage of -lV square pulse.

The voltage for each channel was set so that the trigger rates from the discriminator were the same (about 21 pulse/second). Channel A voltage -1057V, Discriminator threshold -30mV, Channel B voltage -1001V, Discriminator threshold -30mV. Discriminator.jpeg