Optimal Signal-to-Noise Ratio

PILATUS3 Hybrid Photon Counting detectors are inherently free of dark current and readout noise. The absence of any detector noise guarantees data with an excellent signal-to-noise ratio. Compared to conventional detectors, this allows either the collection of superior data with similar exposure times or equally good data with shorter exposure times per image. A noise-free detector provides the largest benefit when recording weak signals from poorly diffracting samples or at highest resolution. The absence of detector noise is particularly beneficial in data acquisitions with weak laboratory sources.

Highest count rates

PILATUS3 R features DECTRIS instant retrigger technology, which enables non-paralyzable counting and highly accurate count rate correction. The count rate performance closely matches the response of an ideal detector (Fig. 1) at high intensities of up to 1 Mcps per pixel. Thanks to a simple yet precise mathematical model, the small deviations at extreme intensities of 2 Mcps per pixel and above can be easily and accurately corrected for. Both local and global count rates of PILATUS3 detectors are far superior to those of counting detectors based on gas discharge or similar technologies. PILATUS3 detectors are compatible with even the most demanding samples such as strongly diffracting small molecule crystals.

Fig. 1: Count rate performance of PILATUS3 R CdTe detectors. The graph shows the measured (open circles) and theoretical (solid line) count rate performance of PILATUS3 R CdTe detectors across the X-ray intensity range relevant for laboratory experiments in millions of counts per second (Mcps) and pixel. PILATUS3 R CdTe closely matches the response of an ideal detector (dashed line) at high intensities of up to 1 Mcps per pixel. Thanks to a simple yet precise mathematical model, the small deviations at extreme intensities of 2 Mcps per pixel and above can be easily and accurately corrected for.

Excellent Point-Spread Function

The point-spread function (PSF) describes the spatial resolution of a 2D detector. Due to the direct conversion of X-rays into charge pulses, PILATUS3 detectors spread virtually no intensity between pixels. The point-spread function of the PILATUS3 detector is thus essentially given by its pixel size (172 ┬Ám) and allows optimally sharp images to be taken. These are free of artifacts typical for other detectors (such as blur, intensity tails, blooming, or streaking). With the sharp point-spread function in combination with the high dynamic range of the detector, closely spaced signals even of largely differing intensity, can be accurately resolved and measured. 

Fast readout and shutterless operation

PILATUS3 R detectors for laboratory instruments read out complete images with lightning speed in only 7 ms. This allows shutterless, continuous acquisition of full images. Nearly instantaneous readout and continuous data acquisition maximize the efficiency and throughput of any instrument.

Ease of maintenance and reliable operation

PILATUS3 R CdTe detectors have low power and cooling requirements. All detector components are operated at room temperature, which vastly simplifies cooling. Instead of relying on failure-prone sealing, PILATUS3 R CdTe are flushed with dry air or N2 for operation. 


Fluorescence background suppression

Fluorescence background suppression is yet another advantage only HPC detectors can provide in laboratory applications. In HPC detectors, X-rays with an energy below a threshold set by the user are not measured. This way, fluorescence background can be substantially reduced or even eliminated from the acquired data. When working with integrating detectors such as CCDs or so called CPADs, fluorescence suppression is not possible and data quality suffers from increased background (Fig. 2).

Fig. 2: Fluorescence suppression decreases background. Fluorescence suppression decreases background. At a threshold energy (Eth) of 11 keV (left panel), Se fluorescence causes strong background. A diffraction image acquired with a charge-integrating detector will suffer from the same fluorescence background in addition to its detector background. At Eth = 13.5 keV fluorescence is effectively suppressed (right panel), which dramatically improves the signal-to-noise ratio of the Bragg spots.

High dynamic range

A counter depth of 20 bits (~ 1 million counts) in conjunction with the absence of detector noise ensures unprecedented contrast and dynamic range, leading to excellent image and data quality. Extremely strong and weak signals can be accurately detected on a single image (Fig. 3). Especially for high-energy photons, it is an important advantage that each photon only generates a single count independent of the photon energy, as this preserves the detector's high dynamic range at all energies.

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Fig. 3: Reciprocal space map showing X-ray Diffuse Scattering of a Bismuth sample studied at 69.7 keV.  Acknowledgement: Measurement by Alexei Bosak (ESRF) at beamline ID15A using  PILATUS3 X CdTe. The detector's high dynamic range is essential for measuring the extremely weak diffuse scattering signal between the strong Bragg peaks. This example from the synchrotron highlights the unique advantages of PILATUS3 CdTe detectors that are also beneficial in the laboratory.