Noise Free Detectors
Hybrid Photon Counting technology achieves noise-free detectors that are free of readout noise and dark current. In single-photon counting technology, every photon is detected individually and counted in the discriminating detector. The required signal processing of the electric charge generated in the sensor is included in each pixel of the readout ASIC.
Each pixel of the readout ASIC is comprised of the following:
- Amplifier: amplifies the electric charge pulse generated in the sensor by an incoming X-ray photon
- Discriminator: generates a digital pulse signal if the incoming charge pulse exceeds an adjustable predefined threshold
- Digital counter: counts the number of generated digital pulses.
This digital detection and storage scheme achieves noiseless determination and readout of the number of detected X-ray photons per pixel. The result is in an excellent signal-to-noise ratio. In addition, the energy threshold provides energy resolution and can be used for low-energy suppression.