Solid State Radiation Detectors

For many applications including medical imaging, homeland security, nondestructive testing and scientific research, solid-state radiation detectors provide the best combination of sensitivity per unit volume, flexibility in packaging, cost, and efficient conversion of ionizing radiation into electrical signals suitable for measurement with modern instrumentation. Solid-state detectors are used for sensing all of the main forms of ionizing radiation including X-rays, gamma rays, charged particles, and neutrons. Charged particles include electrons, beta particles, positrons, protons, alpha particles, fission fragments, and other ions. Solid-state detectors include semiconductors, such as silicon and cadmium telluride, and scintillators coupled to solid state photodetectors such as NaI(Tl) coupled to silicon photodiodes. After more than 50 years of development, this remains an exciting area of research with regular reports of significant advances. The factors which make this such a thriving and growing area in radiation detection technology are the inherent advantages in size, weight, power, the need for high resolution digital imaging, low cost, as well as the availability of high performance computers capable of handling large amounts of data generated by large number of solid-state detector elements. This article reviews the primary mechanisms by which ionizing radiation interacts with matter, how these interactions create electronic signals within the various types of solid-state sensors, the properties of many of the more common solid-state nuclear detectors, and a comparison of their properties as they relate to choosing among them for a particular application. Keywords: ionizing radiation; nuclear radiation; photodiode; scintillator; semiconductor