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The step, delta and 1/ f noise index of a pulse shaper obtained by the frequency-domain analysis have the same results as those obtained by the time-domain analysis respectively. This fundamental relationship is proved by the method of Fourier transformation of the weighting function of the pulse-shaper filter and is referred to as Parseval's Theorem. Noise indices of a trapezoidal shaper that is composed of a rectangular prefilter and a gated integrator are obtained. The results are compared with those two similar gated integrators having an integrator and a differentiator pre-filter to focus attention on their 1/ f noise indices.

A new time-variant pulse shaping amplifier that is composed of a rectangular prefilter and a gated integrator has been designed for low energy gamma-ray and X-ray spectrometers. A rectangular pulse is formed by adding a differentiated signal and an integration of the differentiated signal. Noise indices of trapezoidal filter are calculated as a function of the filter and restoration time constant and event interval. By using this filter, the products of the delta noise index and dead time is obtained to be lower than 5. >

The noise indices regarding the rectangular shaper have been calculated. The results indicate that the time constant of the BLR should be larger than about 20 times that of the prefilter pulse width. A new feedforward type baseline restorer has been developed for the quasi-rectangular shaper. Its time constant can be designed arbitrarily by the value of its components C and R. Therefore, it is simple to determine the compromising point of the delta noise index and the tracking ability for baseline fluctuation. The equivalent circuit of this restorer has an attenuator following the CR differentiator. The existence of the attenuator in the equivalent circuit is a difference from the others. >

We have developed a new time variant pulse processor which is able to adapt the weighting function according to the detector noise characteristics in order to get the best performance from a semiconductor X-ray detecting system. The circuit construction is almost the same as the previously presented trapezoidal filter that was composed of a rectangular prefilter and a gated integrator. The rectangular waveform was formed by adding a differentiated signal and an integration of the differentiated signal with the same ratio. In the new processor it is possible to vary the weighting function continuously by changing the mixing ratio of the differentiated waveform and the integrated one. Noise analysis of the filter has been carried out by using SPICE. This technique is very useful for determining the noise response of a filter simply by the circuit design.

In order to raise the throughput of low-energy X-ray signals appearing in a background of high-energy pulses, a new pulse-processor that measures the rising time of a trapezoidal waveform instead of the peak height has been developed. A rectangular pre-filter and a gated integrator are used to make the wave-shape at the shaper output linear. A rectangular pulse is formed by adding a differentiated step signal and its integration. The rising time of the trapezoidal waveform is inversely proportional to the height of the input step pulse. Therefore, processing time for a high-energy pulse is shorter than that for low-energy ones. Consequently, the pile-up loss of the low-energy X-rays is reduced.

Self-biased silicon detectors with a good carrier collection and a high speed response have been produced by using a wafer with high resistive epitaxial layer grown on a low resistive silicon substrate and also a wafer with the graded impurity distribution formed diffusion technique. The build-in field induced by a large difference of impurity concentration is expected to be effective for sweeping away the high density charge plasma to electrodes before recombination. Energy spectra of fission fragments from /sup 252/C/sub F/ are measured by using the detectors. The results show that the detector will be promising for measurement of heavy charged particles.

Surface barrier silicon detectors with a large active area have been produced by using high resistive n-type silicon crystals, diameters of which are 3 to 5 inches. High quality detectors with a low leakage current and a low noise were achieved by developing the improved surface treatment. Characteristics of detectors obtained are good in energy resolution compared with conventional large area Si(Li) detectors. It has also been confirmed that local dead region is not found from measuring results of photo-pulse injection.

A new baseline restorer which has a capability to eliminate a low frequency noise with a large amplitude is developed by improving the method of gain switching from self control to external control. This baseline restorer is designed for use in a noisy environment in order to eliminate the noise disturbance whose amplitude is comparable to that of the signal.

Sectional surfaces of the lithium-drifted silicon detector are observed using the scanning electron microscope (SEM). Cyclic striation lines are observed in the lithium-drifted region of a detector made from a large-diameter silicon ingot. This is confirmed to be due to a cyclic fluctuation of donor impurity caused by a cyclic change of temperature during floating-zone processing. These materials are judged to be unsuitable for detector application. >

Epitaxial integrated dE1 − dE2 silicon detectors have been developed by using the multilayer epitaxial crystal growth technique combined with the chemical preferential etching technique. These detectors are useful for eliminating events affected by channeling and blocking effects in the identification of heavy ions using multiple detector telescope systems. Characteristics of dE detectors of the integrated dE1 − dE2 type are confirmed to as good as those of integrated E − dE detectors.

The Gaussian pulse forming networks which can be suitably realized by active filters are derived based on the frequency domain analysis. The frequency characteristics and the output waveforms of the results are calculated, and show the favourable features of the filter for nuclear pulse amplifiers. Calculations on the effects of the rise time variations of the detector signal upon the pulse peak height are also carried out.

A log-converter is described which uses a simple series circuit of a log-diode and a resistor, and is particularly advantageous for speeding up the output response. The relations concerning the characteristics of the log-diode and the resistor are studied for the purpose of extending the dynamic range of this log-converter.

A novel time-varying trapezoidal pulse suitable for a high-resolution high-counting-rate spectroscopy system is described. The input signal of the gated integrator has a nearly rectangular waveform approximated by using the directly synthesized Gaussian filter. The product of the delta noise index and the deadtime of this pulse-shaper is less than the best value proposed up to now, which is the theoretical value of that of the triangular waveform. >

High resistivity n-type silicons has been produced from ultra-high purity p-type silicon by neutron transmutation doping. The material produced by this method has better dopant homogeneity and controllability than carefully produced floating zone crystals. The characteristics of a variation of detectors made from this material are equivalent to those of the conventional silicon detectors.

A position sensitive detector has been made on a N-type epitaxial silicon wafer using the epitaxial layer as the uniform resistive layer. The surface barrier electrode is produced on the opposite side of the epitaxial layer by evaporation of gold. The position sensitive detector obtained has good characteristics and moreover it is easy to fabricate. So that the epitaxial technique will be promising even over the conventional ion implantation technique for fabrication of position sensitive silicon detector.

Silicon radiation detectors produced by application of epitaxial crystal growth are reviewed. The epitaxial crystal growth technique is well developed and widely used in semiconductor industries. Therefore, the thickness and the resistivity of the epitaxial silicon layer are well controlled with good uniformities and reproducibilities. The very thin dE epitaxial silicon detector and the integrated E−dE detector are developed based on the uniformity of the thickness of the silicon layer. The epitaxial silicon position sensitive detector is also produced based not only on the uniformity but also on the controllability of resistivity of the epitaxial silicon layer.

The microstructure of the built-in-field distribution of a lithium-drifted silicon detector was investigated using a scanning electron microscope (SEM). It was found that lithium ions diffuse into the region adjacent to the lithium-diffused layer, resulting in an overcompensation of lithium ions in the region expected to be become intrinsic. Effects of the overcompensation on the characteristics of the detector are discussed. It was shown that the pn junction is at the outermost edge of the remarkable difference in donor density at the interface of the original lithium-diffused layer and the lithium-drifted layer. >

The properties of the power law type particle identification formula are studied as a function of the detector thickness. The result shows that the formula is applicable to energies lower than one could expect from the deviations of the power law of the range-energy relationship for heavy ions. For this analysis, the empirical range-energy formula proposed by Zaidins has been improved in order to obtain a better estimate of the range, especially for heavy ions. Experimental results of heavy ion identification thus obtained are also shown.

A high speed decade scaler with a unique centesimal counter at the top stage has been designed using integrated circuits. The centesimal counter consists of two high speed IC flip-flops and two quinary counters in series. By using this circuit configuration, it is possible to improve the counting rate of this decade scaler up to the maximum rate of the first flip-flop. This method will be superior in many respects compared with other methods of high speed decimal counting.

A previously developed nondestructive piezoelectric method for studying the state of polarization of ferroelectric crystals is applied to study polarization switching in barium titanate single crystals.We propose three polarization processes. The first and second processes were designated nucleation and growth by Merz. The third process cannot be measured by conventional pulse methods, and has a very slow polarizing velocity. This indicates the existence of layers which lie between the surface layer and inner layer.Switching time results are considered in the light of the above experiments.

A remarkable characteristic of the surface barrier detector with a side groove cooled down to liquid nitrogen temperature has been observed. That is, an abrupt increase of the output noise at a definite voltage when increasing the bias voltage slowly. This is caused by a carrier injection from the side surface of the groove near the neck narrowed by the side groove. This excess noise disappears after the depletion layer extends into the neck of the side groove. This is confirmed by the fact that the capacitance of the detector decreases abruptly at the bias voltage corresponding to decrease of the excess noise. This detector is capable of operation at a voltage higher than this bias voltage with low noise.

The epitaxial integrated E-dE position sensitive silicon detector has been developed as an extension of the epitaxial integrated E-dE silicon detector. The charge dividing resistor is produced by evaporation of Pd on the E side of the detector. This Pd evaporated layer acts as the surface barrier electrode of the E detector. The good position sensing characteristics will be expected by using the charge dividing resistor made of a P-type epitaxial silicon layer grown on the substrate instead of the evaporated Pd layer.

A remarkable characteristic of the surface barrier detector with a side groove cooled down to the nitrogen temperature has been observed. That is an abrupt decrease of the output noise at a definite voltage in increasing the bias voltage slowly. This is caused by a carrier injection from the side surface of the groove near the neck narrowed by the side groove. This excess noise disappears after the depletion layer goes through the neck of the side groove. This is confirmed by the fact that the capacitance of the detector decreases abruptly with the decrease of the noise at the same bias voltage. This detector is capable to be operated at a voltage higher than this voltage with a low noise. The maximum bias voltage applied to the detector is 3000 V.

N-type extrinsic silicons higher than 10 kΩ-cm were produced from ultra-high pure P-type silicons by the neutron transmutation doping technique. Materials produced by the method has properties in dopant homogeneity and controllability better than conventionally doped ones. This has enabled us to fabricate a high performance detector with a large depletion depth. However, some problems were pointed out as to reverse Current-voltage characteristics, i. e., a reverse current level was so high to use the detector at room temperature. In order to improve this, a study of starting materials, neutron irradiation and annealing conditions are carried out. Significant improvements in detector performance have been obtained by using a material which is annealed at the temperature of 800°C for 10 minutes in an infrared lamp furnace.

Experimental results and computer simulation studies on the dynamic control of cusp loss are presented. The steady‐state plasma is fed into a cusped magnetic field along the spindle axis. The plasma density at the center is 1011 cm−3, and Te ≃ Ti ≃ 10 eV. The rf electric field whose frequency is near the ion cyclotron frequency is applied perpendicularly to the line cusp and to both point cusps. When the rf field is applied the ion density at the center increases by a factor of two and its mean energy reaches up to 50 eV. From the increase of ion density, the increase of decay time by about a factor of ten is estimated. The number density of high‐energy ions above 100 eV confined in the cusp increases by a factor of over fifty. The computer simulation of the rf effect on the line loss suppression indicates a good agreement with the experimental results.

A chemical etching technique is applied to the fabrication of a thin silicon detector with a uniform thickness. The chemical etching has many advantages compared with the electrochemical etching, although good crystals which have high resistivity silicon layers epitaxially grown on heavily doped substrates are required for this purpose.

The maximum switching velocity (ΔP/Δt)max·1/Ps in BaTiO3 single crystals, obtained by the ultrasonic method, is discussed not only as the function of the applied pulse field, but also of the pulse width. Maximum switching current response (dP/dt) measured by the single pulse method and expressed as the exponential function of the field by Merz, is also considered as the limiting case of our expression as the applied pulse width becomes infinitely wide.

Light position sensitive silicon detector (PSD) of surface barrier type has been made from a N-type epitaxial silicon wafer, in which the epitaxial layer is used as the charge dividing resistive layer. The surface of the epitaxial layer is very clean and at the same time defects in the epitaxial layer is very small compared with the silicon layer produced by using the ion implantation technique. Moreover, uniformity of resistivity of the epitaxial layer is very good. These characteristics are favorable to use the epitaxial layer as the charge dividing resistor of the PSD.

The table look up method is applied to the on-line particle identification based on the range relationship proposed by Goulding to reduce the dead time caused by processing of the computer. The quantizing error and the program technique are discussed. The particle identification spectrum, energy spectra of 3He and alpha particles and the total energy spectrum are obtained with sufficient precision. The on-line particle identifier is advantageous in that, not only is it easy to handle, but is also has flexibility compared to the analog circuit particle identifier.