Improved sensitivity X-ray detectors for field applications

Thermoelectrically cooled X-ray detectors based on Si-PIN and Cd1-infinity Zn-infinity Te (CZT) devices are now widely used in field-portable X-ray fluorescence (XRF) instrumentation. A previous generation of detectors provided high-energy resolution comparable to that of cryogenic detectors, but at much reduced sensitivity. Recent research at Amptek, Inc., Bedford, MA, has explored several approaches to improving the sensitivity of the detectors for higher energy X-rays. First, larger volume Si-PIN detectors have been integrated with two-stage coolers and Amptek's low-noise electronics. Second, CdTe M-pi-n detectors have been successfully integrated with the thermoelectric cooler hybrid. These devices have many practical advantages for X-ray spectroscopy. Third, a "dual" detector has been developed, consisting of an Si-PIN for high resolution at the lowest energies stacked on a high-Z semiconductor detector for higher sensitivity at the higher energies. The design and performance of sensors utilizing these three approaches will be presented and the results compared with theoretical expectations. All of these detectors are now commercially available and used in commercial products.