CdTe detectors have came a long way in the last few years. 3-4 keV resolution on Cs-137 is now common for a 1x1x0.2 cm detector. This web link is a sales reference from a company called Radiant Detector Technologies.
http://www.radiantdetectors.com/rad200/rad200.htm
The traditional problem of charge-trapping within the crystal still exists. The trick to achieving a high resolution spectrum the resolution is to measure the signal degradation for each output pulse, then tweak the pulse amplitude accordingly. I have been doing this for about 10 years, using older circuitry designed for correcting for ballistic deficit in coaxial germanium detectors. This vendor has implemented a pulse handling scheme designed for a planer CdTe detector. They use a high quality detector mounted on a peltier cooler.
The detectors are starting to see routine use in verifying inventories of nuclear material.
The small size of the detector limits their use to assay of large quantities of material. In the future, a relatively new implementation of a co-planer grid looks promising.
Another promising development for high resolution room temperature detectors is a high pressure xenon detector. It is a gas filled detector that operates at around 1000 psi with a density of nearly 1g/cc. The detector also exhibits charge trapping. I believe a similar circuit to adjust the pulse amplitude could be developed for this detector, and coupled with a cooler or heater, and include some automated gas handling capabilities, this detector could also be commercialized. A reference link is:
http://www.inst.bnl.gov/GasDetectorLab/XenonDetector/IEEE97/IEEE97.html
Brian Keele
>>Date: Thu, 5 Dec 2002 3:03:39 +0200
From: Dimiter Popoff <
tgi@cit.bg>
Subject: Re: MEDHP-SEC: Article: High Security Trips Up Some Irradi
>>My question would be, however, what makes you think CdTe
resolution is good enough to do the job (i.e. identify nuclides
which make a false alarm and be certain enough to stay silent)?
I don't think anything less than HPGe would do the job.<<