Berkeley Nucleonics is now able to offer unprecedented specifications andversatility
in a precision pulse generator. The Model PB-4 provides eithera tail or flat
top pulse with an integral linearity of +/-50 ppm and an amplitudetemperature
coefficient of +/-5 ppm/°C. The Model PB-4 is designed totest stability, linearity,
and resolution of nuclear instruments employedin high resolution spectroscopy.
It also offers the high count rates thatare so important in many of these
• Flat Top or Tail Pulse
• Rep Rate 250 kHz .
• Rise and Fall Times Independently Adjustable
• Output Impedance 50 ohms
• Temperature Coefficient+/-5 ppm/°C
• Integral Linearity +/-50 ppm
• Amplitude shift less than 0.03% at 50% duty factor
• Use as a reference peak for spectrum stabilization
• Testing count rate effects up to 250 kHz
• Measuring differential and integral linearity of pulse height analyzers
• Measuring noise from preamplifiers and amplifiers
The Model PB-4 employs a solid state chopper (no mercury relays) which sampleseither
an internal DC reference voltage or an externally supplied referencesource.
The output of the chopper is connected to a high gain, fast slewrate operational
amplifier to provide the possibility of driving heavy loads.The internal DC
reference source, the chopper and the operational amplifierare all enclosed
in a proportional control oven whose internal temperaturechanges only 0.01°C
for a 1°C change in ambient.
A sliding pulse generator provides a pulse train of linearly increasing(or
decreasing) pulses to test the differential linearity of multi-channelpulse
height analyzers. To obtain a sliding pulse train from the Model PB-4it is
necessary to connect a Berkeley Nucleonics Model LG-1 Ramp Generatorto its
External Reference input. See diagram below. The solid-state chopperin the
Model PB-4 samples the ramp at periodic intervals. The output ofthe Model
PB-4 is then connected to the pulse height analyzer. If the analog-digitalconverter
is linear and the magnetic core storage is functioning correctly,an equal
number of counts will be stored in each channel and the displaywill be a horizontal
straight line as at A. However, if the analyzer isnon-linear the display may
curve up as at B. If the magnetic core storageis defective there may be a
notch in the display as at C. The differentiallinearity of the sliding pulse
train is better than +0.1%. The above approachis the fastest, most accurate
way of testing a pulse height analyzer.
Now, Berkeley Nucleonics offers the Model PB-5. This upgrade to the Model PB-4 includes a built in ramp and full programmability. This allows faster test protocols to be performed and gives the end user a repeatable approach to linearity measurements and verification. See the Model PB-5 for more here.