SU405456A1 - - Google Patents

Description

one

The invention relates to the field of registration of rare acts of the division of der.

Usually, dielectric detectors of charged particles (minerals, glasses, high polymer organic films) with a certain threshold of sensitivity are used for this purpose, which allows experiments to be conducted in the background of P, y radiation, neutrons, light charged particles. These detectors have a small background of their own, and are characterized by ease of processing and viewing.

A commonly used visual viewing under a microscope makes it possible to unambiguously identify traces of fission fragments, but it is very laborious, which makes it impossible to search for traces at densities less than 1 trecan of 100 cm.

Another way to search for traces using a spark sample of a dielectric irradiated with fragments allows searching for traces over large areas of detectors. In this case, the dielectric film after irradiation and chemical treatment is placed between two electrodes, to which a voltage of a few hundred to several thousand h volts is applied; in places where fragments pass through plastic, a spark breakdown occurs.

This method eliminates the visual viewing of the detectors, however, the spark breakdown destroys the tracks from the fragments, which makes it impossible to identify them. Plastics used have their own

a background that does not allow reliable recording of nuclear divisions at a density of less than 1 trecan of 10 cm, since mechanical damage and own plastic defects lead to a background corresponding to a single breakdown of 10-30 cm

The purpose of the invention is to accelerate the search for traces of fission fragments.

The goal is achieved by the fact that the proposed method exhibits two geometrically

combined layer of the detector, one of which (thin) serves to search for traces by the method of spark sample, and the other (thick) is viewed visually only in areas located near the places of the spark sample

thin detector, and the thin detector is etched only from the side facing the thick detector.

If, after passing through a thin layer, the fragment has enough energy to pass 2 mmk in the second detector, it is uniquely identified visually by the diameter, length and depth of the trace in that detector. Registration of background events is excluded.

since visual identification of traces is made in a thin detector in the spark probe masses.

To ensure the geometric alignment of the layers, a thin plastic is thermally glued around the perimeter onto the thick one. After exposure to the drug, the layers are etched in NaOH solution with a specific gravity of 1.22 g / cm. In this case, a layer of lavsan, used as a thick detector with a specific gravity of 1.4 g / cm, is immersed in the solution, while a thin detector (polycarbonate) with a specific gravity of 1.2 g / cm freely floats on the surface and is etched only one side. Such etching leads to a significant decrease in the counting (by a factor of 4–5) from accidental damage and defects of the plastic layer, revealed during spark breakdown.

To reveal traces of pressure shards, a layer of polycarbonate is placed on a polished metal surface and is covered with a thin aluminum foil on top. A high voltage is applied to the electrode. In places where fragments or defects pass, a spark test occurs. With this effect, the aluminum foil layer is sprayed and the area adjacent to the spark path is deformed and moved away from the plastic, which prevents re-breakdown in the same place.

The layers of polycarbonate and lavsan are then combined and a round area is marked on lavsan by means of a special piercer.

3 mm in diameter, which is then viewed under a microscope.

The proposed method may have other modifications; For example, a thin layer of fissile material can be placed between thin and thick dielectric layers. Then one of the fission fragments passes through a thin layer, and the other is recorded in a thin layer of plastic. As a detector, other recording substances can be used, in particular, thin micas, cellulose nitrate and acetate, etc.

Subject invention

Claims (2)

1. A method for registering rare divisions of atomic nuclei using dielectric detectors with visual identification of traces of fission fragments, characterized in that, in order to accelerate the search for traces of fragments, two combined detector layers are exposed, one of which, thin, serves to search for traces using the spark the sample, and the second, thick, are viewed visually only in the zones located near the place of the spark sample of the thin detector. 2. A method according to claim 1, characterized in that, in order to reduce the total visual viewing area of a thick detector by reducing the background resulting from etching the structural and mechanical defects of the thin detector, the latter is etched only from the side facing the thick detector .