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Detailed introduction
The Model 9327 1 GHz Amplifier and Timing Discriminator is compact and about the size of a preamplifier and integrates two functions typically required for picosecond timing of ultrafast detectors. It is ideal for fluorescence/phosphorescence lifetime spectroscopy measurements, time-of-flight spectroscopy and lidar applications. Model 9327 is optimized for use with millivolt signals generated by microchannel plate detectors, microchannel plate photomultiplier tubes, fast photodiodes, and fast discrete dynode photomultiplier tubes. The compact construction allows for extremely short cable connections between detectors and amplifiers, thus avoiding distortion of sub-nanosecond signals from these detectors. The timing discriminator output logic pulses can be transmitted over longer cables to the rest of the time spectrometer without affecting picosecond time resolution.
The amplifier provides 1 GHz bandwidth to minimize the effects of noise and rise time on timing jitter on detector pulses as narrow as 250 ps. The 50 Ω amplifier inputs include diode clamps to protect against overload pulses. Jumpers mounted on the PC board control coarse gain to produce two full-scale input pulse amplitude ranges: 0 to -30 mV and 0 to -150 mV. Trim gain control changes gain over a nominal 2:1 range. An oscilloscope is not required to adjust the gain because the over-range LED indicates when the pulse amplitude exceeds the amplifier's full-scale limit. Detector and/or amplifier gain can be increased until the overrange LED lights up, then decreased until the LED goes off. This ensures that the pulse utilizes the entire linear range of the amplifier.
The timing discriminator uses zero-crossing technology to handle pulse widths from 250 ps to 5 ns without the need to adjust pulse shaping cables. Zero-crossing technology achieves minimal timing jitter and wander as a function of pulse amplitude. It is optimized for sub-nanosecond pulse widths but can accommodate pulses up to 5 ns in width. When using a 300 ps input pulse width, the offset of the timing output (wandering) as a function of pulse amplitude is typically less than ±40 ps over the first 90% of full scale. Since the effect of 9327 is negligible, the detector is usually the main source of timing jitter. Model 9327 includes a noise discriminator that is adjustable over a major portion of the full scale range. With the detector event source turned off, the discriminator threshold can be adjusted before the associated LED lights up due to noise triggering. Then, adjust the threshold until the LED just goes out, ensuring that the discriminator is not triggered by noise.
Model 9327 provides two fast negative NIM logic signals and is suitable for operating other timing instruments with picosecond time resolution. It also has a 100 ns wide TTL output for counting applications. In addition to its excellent performance in high-resolution time spectrum measurements, the Model 9327 can be used in single photon and single ion counting applications.
A 3-meter long self-contained power cord terminated in a 9-pin D-type connector is used to power the device. Power can be obtained from the 4002P Portable Power Supply, the 4003 Preamplifier Power Output Module, or the mating connector on any ORTEC Spectrum amplifier. Alternatively, a DC source in the range of +12 to +15 V at 350 mA can be connected to the designated pins on the power connector.
