Multicolor Detectors Research Articles

Discriminated neutron and X-ray radiography using multi-color scintillation detector

A new conversion screen Gd 2O 2S:Eu is developed, which emits red light on irradiation by thermal neutrons. By applying this in combination with the currently used Gd 2O 2S:Tb, a green-light scintillator, in the radiography under a neutron + X-ray coexisting field, we can easily separate the neutron image and the X-ray image by simple color-image processing. This technique enables a non-destructive and detailed inspection of industrial products composed both of light elements (water, plastics, etc.) and heavy elements (metals), widening the horizon of new applications.

ChemInform Abstract: Development of Analytical Technologies for Human Genomic DNA Using Capillary Electrophoresis and Their Applications

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Development of analytical technologies for human genomic DNA using capillary electrophoresis and their applications

Capillary electrophoretic systems equipped with a multi-color detectable laser-induced fluorescent DNA detector (CE-LIF) were developed. We examined the efficiency and the performance of the CE-LIF systems for the high-speed DNA sequencing and DNA diagnosis for human diseases. The effect of the gel composition, electric field strength, and capillary length on the separation of DNA sequencing reaction product was investigated in order to achieve high-speed DNA sequencing for large-scale sequencing in the Human Genome Project. The CE-LIF system is successfully applied to ultrafast cDNA sequencing for human and yeast genomes. Under optimum separation conditions, only 10 min is required to sequence 300 base DNA. A polymer solution of cellulose derivative was utilized as a sieving medium for the CE-LIF system and gave excellent resolution of polymerase chain reaction (PCR) amplified polymorphic loci on the human genome. The CE-LIF system is successfully applied to the DNA diagnosis for cancers through CA repeat analysis of human D8S 1218 locus, heart diseases through VNTR (variable number of tandem repeat) analysis of human apolipoprotein B gene and Alzheimer's disease through RFLP (restriction fragment length polymorphism) analysis of human apolipoprotein E gene with high-speed and high resolution. Capillary affinity gel electrophoresis was developed as a new technique for the recognition of the specific DNA base and/or sequence. This technology is also applicable to the characterization of binding properties of DNA based drugs. The principle, the theory, and the methods of capillary affinity gel electrophoresis are presented. This technique is applied to the determination of association constants between an affinity ligand and oligonucleotides. The great potential of capillary affinity gel electrophoresis for the detection of the mutation on DNA is illustrated.

Optimized Three-Color Detector Based on a-SiGe:H Heterojunctions

AbstractBandgap and μτ - (carrier mobility x lifetime) - engineered multi-color nipin detectors with three linear independent curves of the spectral response in a range from 470nm to 670nm are successfully fabricated. The spectral response of nipin structures employed as two terminal devices shifts by the applied voltage. Switching transients after changing the color sensitive voltages under different monochromatic illumination conditions are investigated and can be classified in different cases. In order to improve the understanding of the photo current transients, we have characterized the influence of different illumination conditions on the voltage dependent capacitance behavior. To verify the capacitance measurements, a SPICE model has been developed, which describes the transient behavior of the detector. The simulations are in good agreement with the experimental data and support the explanation of the transient cases after bias switching. Based on these results further optimization criteria to accelerate the transient behavior are presented.

Multicolor voltage-tunable quantum-well infrared photodetector

A novel concept for a quantum-well infrared photodetector (QWIP) with a spectral response peak tunable by an external voltage is described and tested experimentally. This multicolor detector structure is made by stacking conventional (one-color) QWIPs, separated by thin, heavily doped layers ( approximately=90 nm in the test structure). The most important feature is that externally applied DC voltage is distributed among the different one-color QWIPs according to their DC resistances. Each one-color QWIP therefore turns on sequentially in the order determined by its resistance. >

Epitaxial IV-VI Semiconductor Films

ABSTRACTEpitaxial films of IV-VI semiconductors and their alloys form the basis of an infrared detector technology that offers advantages in material stability as well as spectral versatility. These films are prepared by epitaxial hot-wall techniques and their material properties are essentially the same as those of bulk crystals. Because of their stability, multilayer growths of the materials can be achieved in a straight-forward manner. To date, multi-color detectors and small scale two-color detector arrays have been demonstrated successfully. A brief review of the growth method and the growth characteristics is given. Recent advances in superlattice research, especially those of interest to electro-optical devices, will be discussed. These include persistent photoconductivity and sub-bandgap optical transition.