Ryuji Igarashi

Pulse Height Distributions of a GM Counter

Pulse height distributions of an organic GM counter were investigated. The experiment was so performed that the pulse height held a one-to-one relation with respect to the electric charge released within the counter. Some of the distributions observed showed two or three peaks. This result is a contradiction to that expected from a normal Geiger behavior. In order to interpret the results, various discharge modes and the effect of radiation sources are discussed.

Suppression and utilization of spurious pulse occurrence in organic GM-counters

The authors have made a study of suppression and utilization of spurious pulse occurrence in organic GM-counters. Almost all spurious pulses in the organic GM-counter are the delayed pulses which occur being dependent upon the radiation intensity. The occurrence rate of the delayed pulses against the radiation intensity is affected by the intensity of the electric field in the vicinity of the cathode of the GM-counter. The occurrence of the delayed pulses can be suppressed when the electric field in the vicinity of the cathode is kept at high value. On the contrary, the occurrence of the delayed pulses can be utilized for the dosimetry of the pulsed radiation by means of increasing the space of the weak electric field in the GM-counter.

Evaluation of fluctuating dead times by time interval distribution measurement

In real counting systems, there exist dead times, during which the systems cannot correspond to incoming signals. Generally, the dead times are considered to fluctuate. In this paper a method in order to derive a probability density function f(s) of fluctuating dead time s is described. A time interval distribution was used to derive f(s). The method can become a promising tool for investigating the mechanism of real counting systems. As an example our method was applied to a Geiger-Muller counter in order to evaluate its aging effect. >

A Method for Increasing the Exoelectron Detection Efficiency using Afterpulses in a Counter

Successful results for increasing the TSEE count using a gas flow GM counter to make full use of afterpulse is described. As has already been reported, afterpulses from a GM counter can occur, depending on the intensity of the incident ionizing radiation. The occurrence can be enhanced by a counter operation that transiently lowers the wire potential to a value negative to ground when a counter delivers an output pulse (INT–SW operation). This experiment showed us that an INT–SW operation can be used in some cases as a means to increase the TSEE detection efficiency or sensitivity.

A Proposal to Increase the Count Rate of a Discharge-Type UV Detector

An attempt to increase the count rate of a discharge type UV detector is presented in this report. The proposed principle is to decrease the dead time of the detector by reducing the recovering time of the driving circuit. With the recommended resistor-capacitor circuit, an appreciable reduction is impossible. The reduction is realized by a transistor switch.

Software random pulser for use in a laboratory

A software-based random pulser using a microcomputer is described. The pulses are output from a printer I/O port of the computer. The highest repetition rate achieved is 0.9/spl times/10/sup 5/ [pps].<<ETX>>

Derivation of probability density function of dead times from time interval distribution measurements

When nuclear radiations or photons having a mean occurrence rate f/sub 0/ are detected by an ideal detector, the pulse train coming out of the detector also has a mean rate f/sub 0/. A method for deriving a probability density function f(s) for fluctuating dead time s in a real system is described. In the method, a time interval distribution (TID) is used. To obtain f(s), the true rate f/sub 0/ had to be determined from the TID result. Although f/sub 0/ was determined by an approximation and, therefore, the f(s) obtained was also an approximation, the method can be applied to various fields. An example of an application to a GM counter is presented.<<ETX>>

A Proposal for Anticipating Magnet Coil Breakdown by Means of Discharge Pulse Counting.

The result of our investigation whether it is possible or not to anticipate the electrical breakdown of magnet coils used in magnet relays is reported. We employed the method of counting partial discharge pulses. Magnet relays used in various power facilities sometimes come to brekdown. It is faborable if we anticipate the failure of magnet coils beforehand. We examined the current pulse characteristics of partial discharges. From our experiment and statistical treatment of the data we concluded that the discharge pulse counting method is useful for anticipating the failure of magnet coils used in power systems.

Problem on a digitization of a time interval distribution

Distortion of a time interval distribution, due to digitization with an asynchronous clock counting method, is discussed for Poisson random signals. A condition enabling one to neglect the distortion is derived and is applied to measurements of GM‐counter after pulses.

After-Pulses in a GM-Counter Caused by Radiations from Radioactive Nuclide

A method of increasing the counts for a random source in an organic-quenched GM-counter is reported. A large increase in counting rate was observed when the wire-potential was lowered succeeding the occurrence of a Geiger-discharge. A distinct peak in counting rate exists against the variation of the wire-potential. Even under such conditions that the great increase is induced, the counting rate is dependent on the intensity of the incident rays. Negative ions are proposed as being the dominant factor in this phenomenon.