Detectors
We equip our measurment systems with detectors produced by manufacturers with long-term experience in this respective field such as Ritec, Amcrys-h, Yafi, BSI, DSG und VacuTec.
In radiation measurement technology, there are detectors for alpha, beta and gamma radiation and also for neutrons. Further it has to be distinguished between detectors which just allow counting and detectors which can be used for spectroscopic measurements.
An example for counting detectors are e.g. Geiger-Mueller tubes and He-3 neutron detectors.
Although spectrometric detectors are also available for alpha and beta radiation, the mostly important detectors for nuclide characterisation and for use in conjunction with the MCAs are spectrometric gamma detectors. These detectors can be characterized by their energy resolution and by their sensitivity.
Semiconductor detectors
... are principially diodes, which are operated in reverse direction and have a large depleted volume. This diode is coupled directly to a charge sensitive preamplifier.
High purity germanium detectors (HPGe), cooled by liquid nitrogen, have the best energy resolution. Due to the cooling, they are quite clumsy, its quite an effort to operate them and they are also expensive. HPGe detectors are available with sensitivities comparable to large CdZnTe detectors up to medium sized NaI detectors.
Cadmium-Zink-Telluride detectors (CdZnTe or CZT detectors) are also semiconductor detectors, but operate at room temperature. Their resolution is significantly worse than HPGe but much better than any scintillation detector. A typical property of CZT detectors is that only small detection crystals are available and therefore the sensitivities are rather low. But this may be an advantage in some cases where measurements have to be performed in high radiation fields or a high spatial resolution is desired.
CZT detector are available in planar and semispherical versions. Planar detectors are good at energies <100 keV, semispherical detector give good spectra up to 2 MeV.
Scintillation detectors are mostly special salt crystals, which emit light when absorbing a gamma quant. This light is collected by a photo multiplier, in some cases by a sensitive photo diode. The spectroscopical resolution of scintillation detectors is rather low. A further problem is that the energy calibration is quite sensitive to temperature changes. But they are available at very high sensitivities for quite moderate prices. Most common a scintillation detectors from NaI (sodium iodide), which exhibit almost the best energy resolution.
A newer developement are detectors from LaCl3 (Lathanum chloride) or LaBr3 (Lathanum bromide), which provide up to two times better resolution than NaI detectors. But Currently they are very expensive, and the lanthanum's own radioctivity causes inaccuracies during measurements with low shine level.
Other common detectors are made from CsI (caesium iodide) or BGO (bismuth germanate), which have a still better volume specific sensitivity than NaI. CSI detectors are also available with photo diode and are therefore quite compact. At last, there are also detectors with plastic scintillators available. Their resolution is bad and hardly useful for spectroscopy, but it is the cheapest method to get a sensitive detector.
Available Devices
Natriumiodid detectors (Scintillation detectors)
Cadmium-Zink-Telluride detectors (CdZnTe)
Germanium detectors (HPGe) on request
plastic scintillation detectors