P7887 Multiple-Event Time Digitizer

PCI based 4 GHz Multistop TDC, Multiscaler, Time-of-Flight, P7887

The model P7887 is a 250 ps time bin, 4 GHz multiple-event time digitizer (TDC). It can be used in ultra-fast Multiscaler/TOF systems, in Time-of-Flight mass-spectrometry and time-resolved single ion- or photon counting.

In operation the sweep is started by a user supplied start (trigger) pulse. Then subsequent events detected at the stop inputs are recorded, each in a specific time bin corresponding to the time of arrival relative to the start pulse. Compared to non-multihit devices the P7887 can accept a new stop event as soon as 250 ps after a prior event - limited by the max. count rate of 4 GHz only. The P7887 is designed with fully digital circuitry capable of accepting peak (burst) count rates of up to a full 4 GHz.

The P7887 has been optimized for the best possible pulse-pair resolving while providing state-of-the-art time resolution available in digital designs. Two built-in 4 GHz discriminators can be adjusted for a wide range of signal levels. The large single sweep time range enables the user to take data of up to 1 s, with an offset of up to 68 seconds with a time resolution of 250 ps. A PLL oscillator assures a resolution of typically <180ps FWHM at a full scale time range of 1 microsec (measured in the last time bin of 4000 time bins, for 30 min).

The FIFO memory buffers all stop events at full speed (4 GHz) for at least 2 microseconds while a second 16k FIFO buffers the PCI transfer. Thus, the P7887 histograms or stores data at rates of approx. >11,000,000 events/second. For experiments requiring repetitive sweeps the spectral data obtained from each sweep can be summed in the PC enabling very high sweep repetition rates up to wrap around speed.

The P7887 is designed with "state-of-the-art" components which offer excellent performance and reliability.

The high-performance hardware is matched by a sophisticated software delivered with each P7887. MCDWIN - the MS-WINDOWS-98/NT/2000 based operating software - provides a powerful graphical user interface for setup, data transfer and spectral data display.

A DLL (Dynamic Link Library) with example programs for "C", Visual Basic and LabVIEW is available for operation in a Laboratory Automation environment.

Our 2-Year Warranty covers all types of FAST ComTec Multiscalers. 

 The main features are:

  • Fully digital design
  • 250 ps time-resolution
  • 4 GHz max. count rate (burst)- 250 ps puls pair resolution
  • Start- and Stop-Input via built-in 4 GHz, +/- 1 V falling-edge discriminators, sensitivity: < 10 mV
  • 38 bit dynamic range (32 ns to 68.7s pogrammable range with 250 ps resolution)
  • No dead time between time bins, No missed events, No double counting
  • On-board FIFO for ultra fast data transfers at approx. >11,000,000 stop events/sec to the PC for data storage in list-mode or on-line histogramming.
  • Operating modes: Continuous (wrap around), stop after sweep and sequential
  • Two versatile, software configurable Sync-outputs for triggering of external devices
  • Ultra high sweep repetition rates up to wrap around speed
  • Optional Tag inputs (8) with 16 ns time resolution
  • Optional insertion of "Start-of-Sweep" marker into the list-mode (event by event) datastream
  • Presettable 32 bit sweep counter
  • Programmable acquisition deleay and trigger hold-off after sweep
  • Up to four P7887 can be operated in one PC
  • User configurable "GO"-line I/O for experiment synchronization (compatible with other FAST ComTec devices)
  • 8-bit digital I/O port

Typical applications are:

  • TOF Time-of-Flight Spectrometry with exceptional dynamic-range and time resolution of 180 ps FWHM  @ 10 us and 350 ps  @ 1 ms, data taken for 60 minutes 
  • Static TOF SIMS secondary electron Mass-spectrometry - used for example in plant pathology, analyzing molecules from biological samples 
  • Quantum Cryptography research 
  • Laser-induced fluorescence spectroscopy in biological samples 
  • Laser-induced photo-electron spectrometry to analyze the electronic state of gas and solid state samples 
  • Single molecule counting 
  • Single photon counting 
  • LIDAR (4 cm spatial resolution)