• For picosecond timing with mV signals from
Microchannel Plate Detectors
Microchannel Plate PMTs
Fast Photodiodes
Fast Photomultiplier Tubes
• 1-GHz Amplifier and Timing Discriminator are
internally matched for minimum walk and timing jitter
• Walk typically <±40 ps over the top 90% of full scale
• Jitter <20 ps FWHM at 50% of full scale
• Optimized for pulse widths from 250 ps to 1 ns; accepts pulse widths up to 5 ns
• Selectable input pulse height range: 0 to –30 mV, or 0 to –150 mV full scale
• 2:1 Fine Gain control
• Over-Range LED for precise gain adjustment without an oscilloscope
General
The Model 9327-P 1 GHz Amplifier and Timing Discriminator combines into one compact module the two functions normally needed for picosecond timing with ultra-fast detectors. It is ideal for Time-of-Flight Mass Spectrometry, Fluorescence/Phosphorescence Lifetime Spectrometry, and LIDAR applications. The Model 9327-P is optimized for use with the millivolt signals produced by microchannel plate detectors, microchannel plate photomultiplier tubes, fast photodiodes, and fast, discrete-dynode photomultiplier tubes. The compact packaging avoids degradation of the sub-nanosecond signals from these detectors by enabling an exceptionally short cable connection between the detector and the amplifier. The timing discriminator output logic pulse can be transmitted over much longer cables to the rest of the time spectrometer without compromising the picosecond time resolution.
The amplifier provides a 1 GHz bandwidth to minimize the noise and rise time contributions to timing jitter on detector pulses having widths as narrow as 250 ps. The 50 W amplifier input includes diode clamps to protect against overload pulses. A PC-board-mounted jumper controls the coarse gain to yield two ranges for full-scale input pulse amplitudes: 0 to ?0 mV and 0 to ?50 mV. A fine gain control permits varying the gain over nominally a 2:1 range. An oscilloscope is not needed to adjust the gain, because an over-range LED indicates when pulse amplitudes have exceeded the full-scale limit of the amplifier. Detector and/or amplifier gain can be increased until the over-range LED turns on, and then decreased until the LED just turns off. This ensures that the pulses utilize all of the amplifier抯 linear range.
The timing discriminator employs a zero-crossing technique that processes pulse widths from 250 ps to 5 ns without the need to adjust pulse-shaping cables. The zero-crossing technique results in minimal timing jitter and walk as a function of pulse amplitude. It is optimized for sub-nanosecond pulse widths, but will accommodate pulses up to 5 ns wide. The shift in the timing output (walk) as a function of pulse amplitude is typically less than ?0 ps over the upper 90% of the full scale range when employing a 300 ps input pulse width. The typical contribution of the 9327 is small, so that the detector normally becomes the dominant source of timing jitter. The Model 9327-P includes a noise discriminator adjustable over a major fraction of full scale. With the source of detector events turned off, the discriminator threshold can be adjusted until the associated LED is turned on by triggering on noise. Subsequently, the threshold is adjusted until the LED just turns off, thus ensuring that the discriminator will not trigger on noise.
The Model 9327-P provides two fast-negative NIM logic signals suitable for operating other timing instruments with picosecond time resolution. A 100 ns wide TTL output is also provided for counting applications. In addition to excelling in high-resolution time spectrometry, the Model 9327-P can be used for single-photon and single-ion counting applications.
