Development of Computer Control System for Neutron Spin Echo Spectrometer

We have developed a computer control system for a neutron spin echo spectrometer (NSE) which has been constructed at C_ cold neutron guide port of JRR-3M, JAERI. This system controls the current of coils, the measurements by counters and the pulse-motor-drivers using a personal computer. The current of the coils is controlled using GP-IB or the D/A converters equipped in the I/O box connected to the personal computer. The current can be inverted using a current invertor controlled by the computer. The computer gets the data from a He^3 detector or one dimensional position sensitive detector (1DPSD) and saves them into hard- or floppy- disks, prints out them or transfers to another computer connected through RS-232C which analyzes the data. The computer programs for this system called NSEC are made of an assembly of the several simple programs (command) which can be rearranged easily. An NSE mesurement can be carried out automatically using the Batch files composed of the commands. This system is very convenient for NSE measurements

Hydrodynamic interactions in the structural fluctuation of a ternary amphiphilic system C12E5/water/n−octaneC_{12}E_{5}/water/{n}-octane

Dynamical fluctuations of microemulsion and lamellar structures in a ternary amphiphilic system C$_{12}$E $_{5}$/water/$n$-octane are studied by means of neutron spin echo spectrometry. The decay rate of the time correlation of the concentration was analyzed in terms of a theory (M. Nonomura, T. Ohta, J. Chem. Phys. 110, 7516 (1999)), in which both van Hove and hydrodynamic interactions are considered. The result shows that the time correlation function is expressed mostly by a single exponential determined exclusively by hydrodynamic interactions