Norimasa Matsumoto

Fixed-height exit bender of synchrotron X-rays above 40 keV

A crystal bender for sagittal focusing has been designed for standard monochromators at SPring-8. The bender does not move the position of the crystal center when the bending radius is changed. Sagittal focusing from 40 keV to 60 keV was achieved by using Si(311) double crystals. The flux density of the focused beam measured at 40 keV was 15 times higher than that of the unfocused beam. The height deviation of the focused beam throughout the measured energy range was within +/- 0.15 mm.

SPRING-8 BEAMLINE CONTROL SYSTEM

The SPring-8 beamline control system is now taking part in the control of the insertion device (ID), front end, beam transportation channel and all interlock systems of the beamline: it will supply a highly standardized environment of apparatus control for collaborative researchers. In particular, ID operation is very important in a third-generation synchrotron light source facility. It is also very important to consider the security system because the ID is part of the storage ring and is therefore governed by the synchrotron ring control system. The progress of computer networking systems and the technology of security control require the development of a highly flexible control system. An interlock system that is independent of the control system has increased the reliability. For the beamline control system the so-called standard model concept has been adopted. VME-bus (VME) is used as the front-end control system and a UNIX workstation as the operator console. CPU boards of the VME-bus are RISC processor-based board computers operated by a LynxOS-based HP-RT real-time operating system. The workstation and the VME are linked to each other by a network, and form the distributed system. The HP 9000/700 series with HP-UX and the HP 9000/743rt series with HP-RT are used. All the controllable apparatus may be operated from any workstation.

Two‐dimensional X‐ray focusing by crystal bender and mirrors

The performance of sagittal focusing for hard X‐rays with a cylindrical bent crystal at the SPring‐8 is described. The bending mechanism is designed for the SPring‐8 standard bending‐magnet beamlines. Two‐dimensional focusing is achievable by combining sagittal horizontal focusing and vertical focusing mirror. The results underline that the two‐dimensional focusing was achieved in the wide energy range by using an adjustable‐inclined double crystal monochromator.

Structural Study of Semiconductive CdTe-ZnTe Alloy by High-Energy X-ray Diffraction

Semiconductive cadmium telluride and zinc telluride mixture (Cd 1 m x Zn x Te) is observed to have ferroelectric behaviors such as the D-E hysteresis measurements, dielectric measurements and thermal measurements that suggest the existent of ferroelectric phase transition. The paraelectric structure in high-temperature phase is zinc-blende structure. An order-disorder type phase transition occurs and the structure of Cd 1 m x Zn x Te crystal changes to ferroelectric pseudo cubic structure. However, the detail of the mechanism of the phase transition and the structure of ferroelectric phase have not been revealed. We performed X-ray diffraction measurements with synchrotron radiation and obtained a clear evidence of short range order or intermediate range order structure in ferroelectric phase. The role of glassy structure in the mechanism of ferroelectric behavior is discussed.

A Diffractometer Control System with Automatic UB‐matrix Refinement

A four‐axes diffractometer control system with automatic UB‐matrix refinement has been developed. The system automatically scans and finds peak positions after specifying a set of indexes, then the system calculates the UB‐martix. Combining with continuous scan, the control system reduces a UB‐matrix determination time. The system was developed based on a message exchanging control framework. Users can control not only a diffractometer but also other components like a monochromator and an insertion device using man‐readable abstract messages. Therefore users easily develop programs for their experiments. Results of test measurements at the beamline BL46XU of the SPring‐8 indicate that the automatic UB‐matrix refinement is working well, and it reduces the refinement time of the UB‐matrix about one fourth.