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Knowledge of electron densities for materials is important for treatment planning for proton and heavier-ion radiotherapy. In order to obtain the electron densities with high precision, we have developed dual-energy X-ray computed tomography using synchrotron radiation. Two monochromatic X-rays with different energies generated from synchrotron radiation enables tomographic imaging which produces a cross sectional image based on electron density plus an additional image based on effective atomic number. Experiments for the dual-energy X-ray CT were made on the BL20B2 beamline at SPring-8. An image intensifier system and a CCD camera were used as the 2-D detectors. The measured electron densities were agreement to within 2% of the theoretical ones. Electron density and effective atomic number provide different contrast in images. Dual-energy X-ray CT can be used for quantitative measurement of the material. [ABSTRACT FROM AUTHOR]

We report on the performance of a fiber-coupled superconducting nanowire single-photon detector (SNSPD) from 4 K down to the ultralow temperature of 16 mK for a 1550 nm wavelength. The system detection efficiency (DE) increased with decreasing the temperature and reached the considerably high value of 15% with a dark count rate less than 100 cps below 1.5 K, even without an optical cavity structure. We also observed saturation of the system DE in its bias current dependency at 16 mK, which indicates that the device DE of our SNSPD nearly reached intrinsic DE despite the device having a large active area of 20\ \mum\times 20\ \mum. The dark count was finite even at 16 mK and the black body radiation becomes its dominant origin in the low temperatures for fiber-coupled devices. [ABSTRACT FROM AUTHOR]

Deals with the development of a charge-successive integrator (CSI) very large scale integration with a wide dynamic range. Architectural design of the CSI; Accuracy of the charge integrator circuit; Method of offset compensation.