Ken-ichi Hasegawa

Measurement of the liquid phase mass in gas-liquid sprays by X-ray attenuation

An optical method for measuring the mass of liquid phase in a spray has been developed into an X-ray method. An X-ray of about 6 keV is used to measure the mass distribution of liquid phase in the spray formed by a concentric injector with water and gaseous nitrogen at one atmosphere of pressure. The possibility of measuring the mass of gaseous oxygen and hydrogen is discussed.

Amorphous silicon position-sensitive detector

Abstract A new charge-integrating-type position-sensitive detector which consists of an amorphous silicon linear image sensor with a Gd 2 O 2 S phosphor sheet and a signal processing system has been developed. The sensor is 256 mm long and 100 μm wide with 2048 elements on 125 μm centres. The system has a spatial resolution of 500 μm and a wide dynamic range of more than 66 dB. The minimum rms noise corresponds to 140 photons/s for 8 keV X-rays.

High Performance Random Pulser Based on Photon Counting

A random pulser featuring high stability, wide range, and good randomness is described. Change of the mean rate per 50°C change of the ambient temperature is less than 0.01%. The mean rate is variable from 10 pps to more than 10 Mpps with good randomness.

High-count rate position-sensitive detectors for synchrotron radiation experiments

Abstract This paper describes several X-ray position-sensitive detectors developed for use in high-count rate experiments at synchrotron radiation sources; (1) a charge-integrating position-sensitive proportional counter, (2) an amorphous silicon photodiode array as an X-ray PSD, (3) a MWPC with a multiple delay-line encoder and (4) a MWPC with carbon-fiber anode wires. The performance of the detectors is demonstrated in two examples of the application: a time-resolved measurement of a kinetic diffraction diagram from contracting muscle and a two-dimensional diffraction measurement of a powder crystal are presented.

A digital divider with extension bits for position-sensitive detectors

Abstract Digitizing errors produced in a digital divider for position-sensitive detectors have been reduced by adding extension bits to data bits. A relation between the extension bits and the data bits to obtain perfect position uniformity is also given. A digital divider employing 10 bit ADCs and 6 bit extension circuits has been constructed.

A 6-Meter Neutron Small-Angle Scattering Spectrometer at KUR

A 6-meter neutron small-angle scattering spectrometer has been constructed at Kyoto University Reactor (KUR) and has been used successfully for various fields of application in these three years. This paper describes overall design principles and the characteristics of the various parts of the spectrometers which can be assembled and disassembled easily at KUR. Some examples of scattering measurements are presented to show the performance of the spectrometer.

Charge integrating type position-sensitive proportional chamber for time-resolved measurements using intense X-ray sources

Abstract A position-sensitive detecting system for time-resolved diffraction measurements with very intensive X-ray sources has been developed. It consists of a charge integrating type gas-filled detector, multichannel analog multiplexers, a signal processor and a memory (120 ch.×128 phases×24 bits). The detector is 120 mm long in effective length by 10 mm×10 mm in cross section with a single anode of 20 μm diameter. One of the cathode planes consists of 120 cathode strips with a pitch of 1 mm. The spatial resolution is equal to the pitch under a certain detector current limit. The gas gain is adjustable to an appropriate value according to the X-ray intensity range of interest. For experiments with 8 keV X-ray sources, maximum absorption rates of 9×10 7 photons/s·mm with low applied voltage and minimum absorption rates of about 3 photons/s·mm with high applied voltage can be achieved. This system was applied to a time-resolved X-ray diffraction study on frog muscle using a synchrotron radiation source at the Photon Factory and we could collect diffraction patterns with a time resolution of 10 ms and only 10 stimulations.

Integral Type Position-Sensitive Proportional Chamber with Multiplexer Readout System

A new position-sensitive detector with a multiplexer readout system for synchrotron radiation measurements is described. The detector consists of many proportional chamber cells with capacitors for charge accumulation. Charges delivered from a detector cell are accumulated in an associated capacitor during a measuring time. The accumulated charges are transferred to a charge-sensitive amplifier through a multiplexer channel which is addressed by binary coded signals. This process corresponds to the integral type radiation measurement which has no dead time in the pulse measurement. Each cell is regarded as a memory cell containing information about X-ray photons. Experiments carried out with a direct X-ray beam show that the detecting system is applicable to a wide range of photon rates from 103 cps to 108 cps per cell.

A real time correlator with a peak detector (with flow measurement application)

A real time correlator with a peak detector whose analysable frequencies are situated in a region from 0.25 Hz-1 MHz has been developed. The peak detector can correctly decide a peak position of a correlation function wave derived from a phenomenon by employing an extrapolation method. With this method, a peak position can be recognized even when the wave is noisy and flat around the peak. An autoranging mechanism for selection of an optimum clock pulse frequency can follow the variation of the peak position corresponding to the phenomenon. A water flow velocity measurement test showed that this real time correlator operated satisfactorily and the peak position of the wave could be correctly located.

A high-speed logarithmic amplifier

Reports on the improvement of frequency responses of a logarithmic amplifier with a Paterson transdiode connection. The improvement of the response speed has been achieved by using a phase compensation technique. Small- signal response analysis of the logging circuit revealed the effects of a series resistor RP and a parallel capacitor CP on the response of the circuit. The improvement of the frequency characteristics is remarkable at high current levels. These facts were proved by the practical logarithmic amplifier.