Model 9353  100-ps Time Digitizer / MCS

High-Burst-Rate Time Spectrometry...
                            from nanoseconds to milliseconds...
                                                                    with 100-ps Precision

• Time-of-Flight Mass Spectrometry
  Exceptionally high data rates and superb digital resolution!

• LIDAR
  1.5-cm digital resolution for 0 to 1,000 km!

• Fluorescence/Phosphorescence Lifetime Spectrometry
  Measure lifetimes from ns to ms with one instrument!

 All in a half-length PCI plug-in card . . .  complete with software for your PC

• 1-GHz Burst Rates: Multiple Stop capability with 1-ns pulse-pair resolving time

• Digital resolution selectable from 100 ps to 13 µs

• Time spans from 51.2 ns to 6.7 ms, (or to infinity with customized roll-over monitoring)

• 512 to 67 M time bins

• Dead time correction function enables a factor of 10 higher event rates

• Half-length PCI card;  up to 4 units in the same computer

• Histogramming, List, Trend, and Chromatograph Modes implemented in software

• Complete with data acquisition, control, display and analysis software running under  Windows® 2000 and XP¹

• ActiveX™ controls provide an easy-to-use programmer’s toolkit

High Data Rates and High Resolution for the Most Demanding Applications

The Model 9353 100-ps Time Digitizer / MCS is a plug-in PCI card that functions as a time digitizer or a multichannel scaler. It measures the arrival times of Start pulses and multiple Stop pulses with a precision of 100 ps. Exceptional digitizing precision, speed and time span² make it ideal for Electrospray Time-of-Flight Mass Spectrometry, Orthogonal-Acceleration MALDI TOF-MS, LIDAR, and Fluorescence/Phosphorescence Lifetime Spectrometry.

The Model 9353 measures the arrival times of multiple Stop pulses after the most recent Start pulse. Deep, cascaded FIFO buffers accommodate burst rates up to 1 GHz and sustained rates up to 10 MHz. The pulse-pair resolving time for Stop events is 1 ns. A dead time correction algorithm, implemented in software, permits increasing the Stop event rate by an order of magnitude, while keeping dead time distortions of the time spectrum insignificant.

Flexible Time Spans and Bin Widths to Suit any Application

The time span following each Start pulse can be as short as 51.2 ns or as long as 6.7 ms, with the selected span distributed over as few as 512 time bins, or as many as 67,000,000 bins. The maximum time span can be extended to infinity utilizing the auto roll-over monitoring with customized software. The width of each time bin can be adjusted from 0.1 ns to 13.1072 µs.

Minimize the Data File Size by Selecting List Mode or Histogramming Mode

The Time Digitizer / MCS can store the time information using either of two modes:

In the List Mode, the Start and Stop events are streamed to the supporting computer and onto hard disk as a list of 32-bit time stamps. This is a productive way to produce a compact file when the Stop event rates are low, and changes in the time spectrum occur over periods shorter than a few seconds. Each time stamp in the list marks the arrival time of a Start or Stop pulse with a precision of 0.1 ns. The time stamp for each Start pulse is referenced to the time at which the data acquisition commenced. For Stop pulses, the time stamp is referenced to the most recent Start pulse. The maximum value of the time stamp is approximately 6.7 ms for Stop pulses, and 125 hours for Start pulses. Either during or after acquisition, specific segments of the list can be selected and histogrammed by the software to display a time spectrum.

The Histogramming Mode produces a more compact file size when the data rates are high. In this mode, the software in the PC sorts and combines the Stop events following multiple Start pulses to form a spectrum of the number of Stop events versus their Start-to-Stop time. This spectrum is a histogram, because the horizontal axis is grouped into bins of 100-ps width. The resulting histogram is saved on hard disk. When the time digitizer is measuring the flight times of photons or charged particles over a fixed distance, this histogram is called the time-of-flight (TOF) spectrum.

More specifically, each Start pulse marks the beginning of a scan through the selected time span. The time stamps for the Stop pulses are expressed with zero time corresponding to the arrival of the prior Start pulse. The arrival time of a Stop pulse determines the appropriate bin in the histogram to which one count is added. This process of adding Stop events to the histogram is repeated for each scan until the desired number of scans has been completed. The resulting histogram is displayed as the number of Stop events (vertical axis) versus Start-to-Stop time (horizontal axis).

Histogramming improves the statistical precision of the data by summing the data from multiple scans. The precision improves in proportion to the square root of the number of scans summed. Histogramming can be performed on the data as it is being acquired, or on the list-mode data recalled from the hard disk.

Chromatograph/Trend Mode.

Perform Chromatograph/TOF-MS Acquisitions or Track Trends with the Chromatograph/Trend Mode

In the Chromatograph or Trend mode, the short-term changes in the Stop-pulse counting rate are tracked in a graph that displays the Trend or Chromatograph. Clicking on any point in this graph causes the TOF spectrum for that point to be displayed. The total number of Stop events in this TOF spectrum determines the ordinate for the corresponding point in the Chromatograph/Trend graph, while the first Start time stamp from the TOF spectrum specifies the abscissa. The TOF spectra from multiple points in the Trend graph can be summed and saved to improve the statistical precision.

 Ready-to-Run Application Software and a Programmer’s Toolkit

The hardware comes complete with standard software for controlling data acquisition, display, manipulation, and storage on hard disk. The software runs under Windows 2000 and XP. In addition to the standard Windows features, the software provides:

• TOF X-axis calibration in user-defined units via least squares fitting to a linear, quadratic or cubic calibration curve.

• Post-acquisition dead time correction.

• Summing multiple TOF spectra to improve statistics

• 3-point and 5-point data smoothing to improve viewing statistics.

• Overlaying and comparing spectra.

• Exporting data in ASCII format.

• Copying display graphs to a file.

• Determining centroid, gross area and net area of a peak.

The software supports up to 4 Model 9353 cards operating simultaneously in the same computer.

ActiveX®‚ Controls provide a programmer’s toolkit to facilitate the writing of custom software. Custom software can take advantage of special combinations of the extensive hardware functions to add different features, or to integrate the 9353 into software controls for a larger system.

Supporting Electronics

Both the Start and Stop inputs of the 9353 include leading-edge timing discriminators capable of processing positive or negative detector pulses in the 50-mV to 5-V amplitude range, with widths as brief as 500 ps. Usually, the detector signal will need some amplification to optimize the timing performance with the 9353. Check the optional equipment list at the end of this brochure for suitable, fast amplifiers.

For applications where the desired time resolution is less than the rise time of the Stop pulse and the pulse amplitudes vary, a low-walk timing discriminator, such as the ORTEC model 935, 9307 or 9327, must be inserted before the Stop input. See the section on optional equipment for further information.

ORDERING INFORMATION

¹All trademarks used herein are the property of their respective owners

²US Patent Number 6,785,194