Recently, the direct detection of very small ion currents, which can be as low as a few ions per second are required in the fields of the mass spectroscopy, nuclear experiments, space science, etc. As the various ion detectors suitable for this purpose electrostatic multiplier, channel multiplier, counter have been rapidly developed. In this paper the designs, characteristics and present status of these ion detectors are briefly described.
In recent years, the photoionization technique has taken a new advance in development, namely, the study of the photoionization using mass spectrometric technique and the study of the energy spectra of the photoelectrons. These techniques has been used to analysis the electronic and vibrational levels of molecules. Here, the physical meaning of ionization threshold law and a few topics on photoionization processes are briefly described.
The process of the phase transition in KNO3 single crystals have been observed through polarizing microscope with a heating stage which can set up a large temperature gradient across the crystal plate. On heating, the transition boundary BII I (from phase II to phase I) starts from the hot end of the crystal and proceeds to the other end making the specimen somewhat polycrystalline. On further heating, recrystallization starts at about 250°C and the front of the recrystallization sweeps over the crystal making the microscope view a little more single crystal-like. On cooling, the boundary BI III appears on the cooler end of the crystal and then the boundary BIII II appears in quick succession. The boundary BIII II usually leaves many small cracks after its passage. However, the speed of the boundary BI III is rather small as compared with that of the boundary BIII II, and shortly after their appearance the boundary BIII II often comes up with the boundary BI III. Thereafter the united boundary BI II proceeds further to the hot end leaving no more cracks.
The. sampling technique is one of the best ways in the high-speed spectrometric methods for analyzing periodically repeatable weak light with short duration. A high speed spectrometer by using a novel photomultiplier gate for signal sampling is described together with a part of the experimental results for demonstrating the instrumental performance. The signal processing electronics, which is used in conjunction with a conventional spectrometer, is composed of the signal sampling photomultiplier circuit, a light source triggering generator and a linear delay system which determines the phase relationship between the light source triggering pulse and the sampling pulse. This apparatus makes it possible accurately to display either time-resolved spectra or rise and decay curves of radiations on a X-Y recorder by simply switching a mode selector. A minimum time resolution of the instrument obtained is 10 nanosecond (10-8 second). The preparation of a jitter-free thyratron light pulser which is useful for testing such an instrument is also mentioned as well as its operational features.
In recent years, the orbital radiation from the electron synchrotron is utilized as a light source in the soft x-ray and vacuum ultraviolet region. In this article, the characieriatics of the radiation are clarified in the case of the INS electron synchrotron. The power spectral distributions, the angular power distributions, and the relation of the emitted power spectrum to the electron energy are given. The practical intensities of the radiation, which enter a 10 micron slit at the experimental site 8 meter apart from the orbit, are tabulated for various wavelengths and electron energies.
The electrical breakdown of shielding window glass is induced indispensably by irradiation, with 60Co-gamma-rays. In order to elucidate the mechanism of the breakdown, electrical conductivity and thermally released current in various glasses irradiated as a function of temperatureunder the condition of temperature-gradient have been studied. The electrical conductivity curve of the irradiated cerium glass shows a positive maximum or a negative minimum at 55°C, according as directions of electric field and irradiation are same or reverse. If the directions of tempera ture-gradient and irradiation are same, the thermally released current shows a positive maximum at 55°C and a negative minimum at 75°C, but if reverse, it shows a negative minimum at 55°C and a positive maximum at 75°C. When the samples are irradiated under the rotation, no maxima and minima are observed. It is suggested that the maxima and minima at 55°C are based on the thermal release of trapped electrons which are entered from atmosphere into sample by Compton recoils. The maxima and minima at 75°C imply the thermal release of trapped electrons which are generated within the sample by Compton recoils. The maxima and minima are also observed in the samples containing titanium or vanadium substituting cerium.
A characteristics of CO2-N2-He laser output power was studied under various discharge currents and total pressures (gas content ratio, CO2:N2:He=4.4:10.2:85.4(%)). A gold-doped germanium detector (77°K) was used to observe the pulsed laser radiation. In a pulsed discharge, the quenching effect of a laser power was observed at a critical current which is independent of total pressures. This phenomenon seems to be explained by the energy distribution of electrons which cause the excitation of CO2 and N2 molecules to vibrational levels in a mixture gas.