1. Observe a very short ( -1 volt, 20 ns wide) pulse on a fast oscilloscope.
- Termination: Observe the effect on the pulse of a) no terminating resistor at the scope, b) 50 ohm terminating resistor at the scope. Always terminate cables correctly if the device input does not provide 50 ohm termination internally.
- Reflections: Using a tee, send a pulse to the oscilloscope input and then on into a long cable. Observe the effect of different terminations on the pulse. Measure the characteristic impedance of the cable with a variable terminating resistor.
- Pulse travel time: Using two oscilloscope channels observe a pulse from the Pulse Generator (Pulser) after splitting it and sending it through one short cable and one long cable. Determine the pulse velocity on the cable.
2. Scaler: Send a pulse train into the Timer-Counter (scaler) and be sure you know how to use the it.
3. Delay box: Using two scope channels, observe one channel delayed with the delay box. Compare the box settings with the observed delay.
4. Discriminator: (See handout on fast electronics)
- Set the Threshold of two discriminator channels to -100 mV using a voltmeter on the Test point (note the factor of 10 in scale). Put short (20 ns) pulses of various pulse heights into a discriminator while observing the output(s).
- Adjust the output pulse width on the discriminator while observing the output pulse train. What happens if the pulse width is longer than the time between pulses? How would this affect a high counting rate experiment?
- While observing a short output pulse from the discriminator observe the effect of adding or removing a terminator from another output of the same discriminator.
5. Coincidence Circuit: Put simultaneous output pulses from two discriminators into a coincidence unit. Observe the output as you change the coincidence unit settings and add or remove the inputs.
6. Delay Curve: Send pulses through two delay channels, through the discriminators and into the coincidence unit. Vary the two delays while observing the pulses at “out” and at “lin out”. Using “out” make a delay curve. Predict the width of this curve before you measure it.
August 17, 2018
Tom Browder