Fast measuring system of energy dispersive x-ray diffraction intensity for synchrotron radiation (abstract)

Abstract

We have developed a fast measuring system of energy dispersive x-ray diffraction intensity. A solid state detector (SSD) has been used to measure the energy dispersive x-ray diffraction intensities. The energy resolution of SSD is almost ten times higher than that of a scintillation counter or proportional counter. For full use of SSD, a fast processing system of the signal is needed, especially when x rays from synchrotron radiation (SR) are used. When SSD is used for x rays from SR, however, we have two problems. One is that the dead time of conventional signal processing system is long, which prevents the efficient use of synchrotron radiation source. The other is that a fast data recording system is needed, because the number of data of a single diffraction spectrum is large. To solve these two problems, we have designed a new measuring system. The system consists of a personal computer and an interface board of multichannel analyzer function. The interface consists of peak hold, fast ADC, memory, add one, and DMA. (1) Improvement of the dead time. We adopted a successive approximation ADC to shorten the conversion time. The dead time is then 2 μs in the present system, which is much shorter than that of the Wilkinson ADC (about 40 μs). (2) Fast data recording. In most conventional MCA, the memory of MCA is separated from that of computer and the data are transferred between MCA and computer. In this case, the data are transferred by GP-IB or RS232C, and the data transfer time is several ten seconds. In the present system, the same memory is accessed by MCA and computer and the data transfer time is zero. This fast measuring system has already been installed at Photon Factory, KEK and utilized to measure the energy dispersive diffraction intensities. We have observed Pendellösung fringe induced by x-ray resonant scattering to make use of this system.