CS260897B1 - Trace computer electrode stop designed to measure both low and high track densities - Google Patents

Abstract

The electrode of the spark trace counter is intended for measuring the density of charged particle traces, such as alpha particle traces or fission debris in trace detectors. It consists of two rings formed by segments, which are folded into annuli concentrically arranged around a central cylinder, with electrical insulation provided by the insulating annuli. The flatness of the entire surface, including the insulating annuli, must be better than ± 0.05 mm. The annuli must insulate the segments and the central electrode up to a voltage of 1,500 V. When measuring high trace densities, individual segments are used separately, which reduces the total capacitance of the electrical circuit and significantly increases the efficiency of trace counting. The solution allows reliable measurement of both high and low trace densities without knowing in advance which trace densities are being measured.

Description

The invention solves the problem of measuring low and high track densities by a spark computer. This method is used, for example, in personal neutron dosimetry, in radiography, eventually. in alpha particle dosimetry and wherever charged particle detectors can be used.

Charged particle traces in organic detectors magnified by chemical processing can be calculated either by microscopy or this process can be automated by a spark stop computer, provided the appropriate detector thickness and appropriate chemical treatment are selected. This procedure has been known since 1970 [Cross, Tommasino: Radiation Effects, V.5 (1970), pp. 85-89). Usually one solid electrode (iron, brass) is used and the other electrode is formed by a thin steamed aluminum layer on a non-conductive substrate. The heat of the spark discharge evaporates the aluminum and thereby electrically isolates the counted track, so multiple counting of one track is virtually eliminated. Due to the fact that the evaporation area of the aluminum on the thin electrode is more than two orders of magnitude larger than the track area itself, especially at higher track densities, electrical tracks not yet counted above the area where the aluminum evaporates are electrically isolated. The size of the vaporized surface on the thin electrode is a function of both the total electrical capacity of the spark gap and the voltage at which the discharge occurs. The total capacity of the spark gap is determined both by the capacity of the respective RC-circuit and by the parasitic electrical capacity of the electrodes used. Reducing the total electrical capacity of the spark gap and thereby evaporating the surface on a thin aluminum electrode can be accomplished by using smaller electrodes [R. Chatham et al., Nucl. Tracks 7 (1983) 113-120). However, the use of a small-area electrode deteriorates the accuracy of counting low track densities, changing the electrodes during measurement is time-consuming, and is also a source of measurement errors.

The above shortcomings are eliminated

Claims (2)

A spark stop counter electrode for measuring low and high track densities, characterized in that it consists of equally sized rings and a central cylinder (3) electrically insulating insulating annulus (4, 5) and alternately interconnected by a spark stop counter electrode consisting of the same electrically Insulated rings are formed of segments folded into annular rings concentrically arranged around the central cylinder. Either individual segments or any combination of segments can be used. When measuring low track densities, all segments are connected simultaneously to give the same track counting efficiency as when using a single electrode with the same area. When measuring high track densities, we use the segments separately to reduce the total capacity of the electrical circuit to reduce the evaporation area on the thin electrode, which significantly increases track counting efficiency, extends track counting to higher densities and extends the linearity of the counted tracks depends on the actual number of tracks. 1 and 2, an electrode of a spark stop computer is shown, consisting of two rings formed by segments 1, 2, which are folded into concentric annuluses arranged around the central cylinder 3, with electrical insulation provided by an insulating annulus 4, 5. This device is an example the solution according to the invention. The segments 1, 2 and the central cylinder 3 can advantageously be made, for example, of brass or stainless steel and the insulating ring 4, 5 of teflon or pertinax. During production it is necessary to ensure the flatness of the whole surface including the insulating rings 4, 5 better than ± 0.05 mm. The insulating ring 4, 5 must insulate the segments 1, 2 and the central cylindrical electrode 3 to a voltage of 1500 V, which is used in forming the tracks. Application of the invention is possible in all applications where solid-phase stop detectors are used for the detection of charged particles, particularly in the nationwide neutron personal dosimetry service, where it allows an order of magnitude increase in measurable neutron dose equivalents up to Sv. so that any combination of them can be used for measurement. The spark stop electrode electrode according to claim 1, characterized in that the rings are formed from segments (1, 2) folded into annular rings, which are concentrically arranged around the central cylinder (3).