Phoswich Detector
Encyclopedia
Originally, "Phoswich detectors were developed to detect low-intensity, low-energy gamma rays, X-rays, as well as alpha
and beta
particles efficiently in a higher-energy ambient background. Some detector designs can measure and separately identify all energies simultaneously."
Scintillator
manufacturer Saint-Gobain Crystals & Detectors (SGC; Hiram, OH) provides a good introduction to this topic. SGC's two-page document states "A phoswich ('phosphor sandwich') is a combination of scintillators with dissimilar pulse shape characteristics optically coupled to each other and to a common PMT
(or PMTs). Pulse shape analysis distinguishes the signals from the two scintillators, identifying in which scintillator the event occurred." The document also describes the operating principles and applications of phoswich detectors and includes two detailed drawings.
However, the technology described by SGC lags behind the needs of many modern medical imaging, pre-clinical (small animal) imaging, security imaging and other radiation detection, measurement and imaging applications, which require economical scintillators and detectors that can provide enhanced spatial information regarding gamma-ray interactions within scintillation materials, primarily to reduce blur in acquired and reconstructed images, achieve improved spatial and contrast resolution, simplify data acquisition devices and reduce system costs.
Research and development firm Radiation Monitoring Devices (RMD; www.rmdinc.com; Watertown, MA) in 2010 announced its development of a monolithic phoswich sensor technology, departing from the discrete designs (with their serious limitations) described by SGC. RMD's novel development, termed the Continuous PhoswichTM scintillator (CPSTM) and detector (CPDTM), provides a number of bits of depth-of-interaction (DOI) information, a significant improvement over the 1 to 2 bits available previously with discrete phoswich scintillators (as described by SGC).
RMD's web site provides an excellent description of the characteristics and advantages of their CPS and CPD technology .
Alpha
Alpha is the first letter of the Greek alphabet. Alpha or ALPHA may also refer to:-Science:*Alpha , the highest ranking individuals in a community of social animals...
and beta
Beta particle
Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay...
particles efficiently in a higher-energy ambient background. Some detector designs can measure and separately identify all energies simultaneously."
Scintillator
Scintillator
A scintillator is a special material, which exhibits scintillation—the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate, i.e., reemit the absorbed energy in the form of light...
manufacturer Saint-Gobain Crystals & Detectors (SGC; Hiram, OH) provides a good introduction to this topic. SGC's two-page document states "A phoswich ('phosphor sandwich') is a combination of scintillators with dissimilar pulse shape characteristics optically coupled to each other and to a common PMT
Photomultiplier
Photomultiplier tubes , members of the class of vacuum tubes, and more specifically phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum...
(or PMTs). Pulse shape analysis distinguishes the signals from the two scintillators, identifying in which scintillator the event occurred." The document also describes the operating principles and applications of phoswich detectors and includes two detailed drawings.
However, the technology described by SGC lags behind the needs of many modern medical imaging, pre-clinical (small animal) imaging, security imaging and other radiation detection, measurement and imaging applications, which require economical scintillators and detectors that can provide enhanced spatial information regarding gamma-ray interactions within scintillation materials, primarily to reduce blur in acquired and reconstructed images, achieve improved spatial and contrast resolution, simplify data acquisition devices and reduce system costs.
Research and development firm Radiation Monitoring Devices (RMD; www.rmdinc.com; Watertown, MA) in 2010 announced its development of a monolithic phoswich sensor technology, departing from the discrete designs (with their serious limitations) described by SGC. RMD's novel development, termed the Continuous PhoswichTM scintillator (CPSTM) and detector (CPDTM), provides a number of bits of depth-of-interaction (DOI) information, a significant improvement over the 1 to 2 bits available previously with discrete phoswich scintillators (as described by SGC).
RMD's web site provides an excellent description of the characteristics and advantages of their CPS and CPD technology .