Features

• Leading edge or crossover-type timing derivation
• Dynamic range 100:1
• Pileup rejection logic
• Exceptional stability - dc-coupled input
• Positive and negative timing SCA outputs
• Source matched logic outputs
• Variable delay of up to 11 µs

Description

The CANBERRA Model 2037A analyzes the peak amplitude of energy pulses from nuclear pulse shaping amplifiers for compliance with energy levels determined by front panel controls, and generates logic outputs which are time derived by the leading edge or crossover techniques. The unit thus combines the conventional single channel analyzer function with that of an excellent but economical timing analyzer.

The leading edge timing technique finds best application in fast-shaped unipolar signals of a fairly narrow energy (pulse height) range. The crossover technique exploits the amplitude-insensitive zero voltage crossing of a bipolar pulse to provide a stable timing reference for a broad energy range. A front panel Mode switch allows selection of either timing derivation.

ENERGY

The logic output (SCA) is provided as both positive and negative NIM-level pulses for input analog pulses whose peak amplitude is between the levels determined by the Lower Level (E) and Window (ΔE) front panel ten-turn controls.

Energy discrimination in the Model 2037A is sharp, precise and stable (drift is less than ±0.005%/°C, full scale). The dc coupled input allows excellent baseline stability limited only by the shaping amplifier's restorer. These significant features permit excellent amplitude discrimination, even in high count rate spectra.

The LOWER LEVEL (E) threshold is calibrated by reference to the regulated NIM supply voltages, and is usable in a range from +0.1 to +10.0 V dc. Linearity of control is limited only by the specified ±0.25% maximum integral nonlinearity of the front panel potentiometer.

The Window (ΔE) threshold is also calibrated by reference to the regulated NIM supply voltages, and is usable in a range from the Lower Level (E) setting to +10.0 V dc. A front panel (ΔE) Range switch allows use of a 1.0 V full scale range for very fine adjustments of the desired energy window.

TIMING

For the leading edge mode, a true low level leading edge technique is employed to minimize timing jitter. To simplify setup and adjustment, the threshold level for the leading edge timing discriminator is set to track the Lower Level (E) control at 50%, up to a limit of 200 mV dc. For reasonably large input pulse heights, then, timing is referenced to the 200 mV dc level. To simplify adjustment of timing dwell for the rise time of the input pulse, that function has been incorporated in an extended range DELAY control. The user can simply set the selected delay for the known time-to-peak of the input pulse (or at least 2X the shaping time constant used in a near-Gaussian pulse) without the need for tedious oscilloscope trimming.