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We developed a silicon avalanche photodiode (Si-APD) linear-array detector to be used for nuclear resonant scattering experiments using synchrotron X-rays. The detector has a 64-pixel or 128-pixel linear array (pixel size: 100 × 200 μm²). Each pixel pitch is 150 μm, and the depletion depth is 10 μm. The multichannel scaling (MCS) system for the detector counted X-ray pulses over 2048 continuous time bins with minimum time resolution of 0.5 ns. The detector system can record a time spectrum of the nuclear radiation simultaneously with an intensity distribution at each pixel. We investigated its performance using synchrotron X-rays and the 128-pixel linear array exhibited a time resolution of 0.5 ns (full width at half maximum, FWHM) at 14.4 keV. A vacuum feedthrough for the 64-pixel linear array system was fabricated to detect low-energy electrons of <10 keV using internal conversion electrons. The feedthrough consists of a fast-transmission flexible flat cable, multi-electrode micro connectors and a build-up printed circuit board. The energy spectra of ~6 keV M-photoelectrons emitted from Tm foil were successively measured in vacuum with one pixel from the 64-pixel linear array using the vacuum feedthrough. The time spectrum was also recorded using the electron signal. [ABSTRACT FROM AUTHOR]

Application of the Silicon-On-Insulator (SOI) technology to a pixelated detector is expected for the imaging experiments using synchrotron X-rays. The SOI pixel detector is advantageous to make a fine pixel with low noise, because there is no mechanical bump bonding. Because the soft X-ray experiments like the surface X-ray scattering (SXS) and diffraction (SXRD) are very important for the surface analysis, we have started to develop a pulse-counting type SOI pixel which is sensitive to low–energy X-rays down to 2 keV. A test-element-group of CPIXPTEG2, was evaluated by using synchrotron X-rays. The CPIXPTEG2 was designed with the double-SOI technology and its total thickness was 75 µm for a smaller dispersion of the charges collected inside the sensor. The non-melting laser annealing was employed in the ground backside to suppress dopant diffusion during activation. We will report on the test results of CPIXPTEG2 using 6 keV X-rays. [ABSTRACT FROM AUTHOR]

The measurement of the nuclear resonant small-angle scattering was achieved by scanning the position of a multi-element avalanche photodiode detector, detecting delayed nuclear resonant signal to investigate microstructures of the electronic states. The nuclear resonant small-angle scattering has been attempted to study the coexisting phase of superconductivity and magnetic order in an under-doped Fe-based superconductor, Ba0.8K0.2Fe2As2. Clear change was not observed in the exponent of the angular profile of the nuclear resonant smallangle scattering in the coexisting temperature. This fact implies the microstructure in the coexisting phase does not have an obvious typical scale but a complex spatial texture. Another attempt was performed for the microstructure in the magnetic properties in an anti-invar fcc Fe-Ni-C alloy to investigate mechanism of the anti-invar properties. An enhancement of the angular profile in a few tens of nm range was observed as decreasing the temperature down to a little below the Curie temperature. This fact implies the existence of the inhomogeneity of magnetically-ordered phase in this range of size, which may related to the anti-invar properties. [ABSTRACT FROM AUTHOR]