Position sensitive solid-state detectors

The future experimental investigations will target in particular the accurate spectroscopy of the excited states in heavy He-like systems. In contrast to the ground-state properties, this topic has almost not been addressed up to now experimentally. In addition, very recently, there has been a considerable progress in developments for the next generation Lamb shift experiments on H-like heavy ions. Here, the first beam-time has already been conducted utilising the high-resolution X-ray spectrometers (in combination with novel position-sensitive solid-state detectors) as well as the X-ray microcalorimeter. 

The second slit box is located on the detector arm between the sample and the detector. The slit nearest to the sample serves as a scatter slit. It is followed by another Soller slit and a receiving slit positioned just before the detector. The detector in this case is a solid-state detector, which is cooled by a built-in Peltier refrigerator enabling to adjust and maintain the detector sensitivity at extremely narrow width to allow only x-ray photons of specific energy to be registered. Monochromatization of the diffracted x-ray beam is, therefore, achieved electronically rather than by physical means (e.g. by a P-filter or a crystal monochromator), which increases the registered diffracted intensity by eliminating losses in the filter or in the monochromator. 

Solid-state detectors are compact, robust, and relatively inexpensive with high position resolution and low power consumption. Because they produce a signal proportional to the incident particle energy, solid-state detectors also provide the energy of individual particles in addition to incidence rate and position information. These features make these detectors very attractive for space science missions. Their main drawback is their loss of sensitivity at low particle energies. In the case of protons current state-of-the-art solid-state detectors lose sensitivity at energies below - 10 keV. 

There are three principal types of position-sensitive X-ray detectors of use for crystallography—the vidicon, solid-state devices (largely charge-coupled devices), and proportional counters. Vidicons are area detectors which use image intensifier techniques to produce TV-type images. They are not count rate limited and are therefore well suited for use with high-flux sources... 

Another kind of linear solid state position sensitive detectors are the Photo-Diode-Arrays (PDA s), which are different from CCD s. A PDA consists of an array of separate photodiodes, each with an associated capacitance and a multiplexing read-out system (see Fig. 21). The charges collected in each cell are simply switched to the output, one by one. Unlike in the case of CCD s, the photosensitive elements are separated completely from the transfer circuity. 

---