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Suitable for high-rate spectroscopy applications
"No Loss" or "Zero Dead Time" (ZDT)
A common method used to calculate count loss at high rates is to extend the acquisition time. The basic assumption must be that the sample does not change over the extended period. This assumption does not hold true when short half-lives are encountered or when the sample is not stationary (e.g., flowing through a pipe). ORTEC has pioneered lossless counting technology in the digital realm. In this method, the spectrum itself is corrected on a pulse-by-pulse basis. The ZDT method also provides accurately corrected spectra and correctly calculated statistical uncertainties.
"Increase throughput" mode
Accuracy at high input count rates may be limited by the speed at which the spectrometer can store data into memory. This is called "throughput limit". Pulse stacking means that beyond a certain point, the rate of data stored to memory decreases as the input count rate further increases, thus degrading the quality of the results. ORTEC increased throughput by 30% by developing a new digital peak detection algorithm that eliminates some of the dead time associated with the pulse peak amplitude determination process.
Suitable for samples in motion
list mode
For cases where the sample is moving relative to the radiation detector, it is often necessary to measure the activity curve as a function of time. Examples of such applications include aerial and land surveying and access monitoring. It is often required that there is no "dead zone" associated with the "acquire-store-clear-restart" cycle. In list operation mode, data is streamed directly to the computer event by event. There is no relevant "dead zone". In DSPEC Pro, each event is timestamped to the nearest 200 nanoseconds. By using the Programmer's Toolkit, data can be reconstructed into spectra for offline analysis via ORTEC's various analysis software products or user-developed code.
Suitable for harsh environments and mechanical coolers
Low frequency noise suppressor (LFR)
The performance of HPGe radiation detectors in environments with mechanical vibration is not very ideal. Microphonic noise reduces energy resolution by adding low-frequency periodic electrical noise to the main signal. Electrical ground loops are also a source of low-frequency electrical noise. More and more HPGe detectors are using mechanical coolers to eliminate the need for LN2, and more and more HPGe detectors are being taken out of the laboratory environment.
DSPEC Pro features a Low Frequency Noise Rejector (LFR) feature that reduces the impact of such noise sources. Combined with high-performance list mode, DSPEC Pro is the instrument for mobile vehicle measurement systems.
Used to increase the resolution of large or neutron damage detectors
Ballistic loss and charge capture correction
The ladder digital filter in DSPEC Pro is the same as in all other ORTEC DSPEC series products. It adjusts filters to optimize the resolution performance of large HPGe radiation detectors, which often suffer from low-energy tailing when ballistic deficits are present. These large detectors are increasingly used in low-level counting applications.
Adjustments are primarily automated using the Optimize function and can also be monitored via the InSIGHT digital oscilloscope mode.
DSPEC Pro offers additional functionality in the form of a charge capture corrector that can be used to mitigate peak attenuation in neutron damaging radiation detectors. Damage to the crystal lattice by neutrons creates "trapping" centers that "retain" some of the charge created by gamma-ray interactions. This will result in a low-side tail similar to a ballistic loss, albeit for a different reason. The charge capture corrector is calibrated or "trained" so that it adds back the pulse height deficit on an event-by-event basis.
