X-Ray Detector Selection Guide

Amptek provides a family of high performance, compact X-ray detectors and associated signal processing electronics. The radiation detectors are custom photodiodes, including the traditional Si-PIN diodes, Silicon Drift Detectors (SDDs), and CdTe Schottky diodes. The detector is mounted on a two-stage thermoelectric cooler along with the preamplifier’s input transistor. The cooler keeps the detector and transistor at -25oC or below, reducing electronic noise without cryogenic liquid nitrogen and drawing <1W. This cooling permits high performance in a compact, convenient package, and has been critical to the development of portable XRF analyzers and high performance, bench top XRF systems.

Amptek’s detectors represent the state-of-the-art in X-ray spectroscopy, delivering the best energy resolution, best efficiency at low energies, highest count rates, highest peak to background ratios, all at low cost and suitable for portable systems, vacuum systems, etc. They are used by OEMs and by laboratory researchers. The core enabling technologies include: the detectors themselves (which are designed and manufactured by Amptek); the low noise JFET and CMOS technology; and the packaging which enables good cooling in a robust system. Amptek has several different basic detectors in this family, sharing the core technology but optimized for different applications.

The image below illustrates a detector mounted on a thermoelectric cooler, on a TO-8 header. The input FET and other components are also mounted on the cooler. A nickel cover (also shown) is welded to the TO-8 header with vacuum inside the enclosure for optimum cooling. In the cover is a window (shown dark blue above) to enable soft X-ray detection. This is typically beryllium for energies > 2 keV, with Si3N4 available for lower energies. The detectors use reset-style preamplifiers.