SU755076A1 - Device for measuring braking radiation energy flow density - Google Patents

Description

The invention relates to a technique for measuring ionizing radiation and can be used in experimental nuclear physics, radiation, technology, defectoscopy and radiation biology.

A device for measuring the bremsstrahlung energy flux density is known, consisting of a front wall, an ionization cavity unit with a collecting electrode, a back wall, an integrated preamplifier, cable entry and an outer sheath [ΐ].

As a result of the action of 15% bremsstrahlung, gas is ionized in the cavity, from the measured value of which information is obtained about the bremsstrahlung flux density.

The disadvantage of the known device 20 is the lack of accuracy of measurements, due to the heterogeneity of the material of the front wall with the materials of the other parts of the device, which give an unaccounted contribution * * *

in the formation of ionization current in the cavity of the chamber.

It is also known a device for measuring the flux density of energy of bremsstrahlung, containing a hollow 30

camera housing with bottom and removable absorbers.

As a result of the bremsstrahlung effect, the gas is ionized in the chamber, according to the measured value of which information is obtained about the bremsstrahlung flux density {2].

A disadvantage of the known device is the low measurement accuracy and the associated long duration of the measurement process. This is due to the presence of parts from dissimilar materials, which lead to a difference in the radiation field near the measurement point from the calculated one and make a contribution to the ionization current that is not taken into account in the calculation.

The purpose of the invention is to improve the accuracy of measuring the flux density of the energy of bremsstrahlung and reduce the measurement time.

This goal is achieved by the fact that the camera body is made in the form of a hollow cylinder with a flat bottom, cantilever mounted on a support post, inside the case there are successively located inserts with blind holes, absorbers and a return diffuser with an external cross-section diameter equal to the internal diameter of the core3

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The inserts, absorbers and return diffusor are tightly pressed to the bottom of the housing and to each other, the housing with the bottom, absorbers, inserts and the return diffuser are made of the same uniform material, such as graphite or aluminum, and the distance from the bottom the openings of the insert, located in front of the return diffuser, to the support column are chosen not less than the mean free path of the electron with the maximum energy in the spectrum.

FIG. 1 shows a general view of a device for measuring the energy density of bremsstrahlung energy; in fig. 2 shows the layout of the device at the accelerator output.

The device consists of a hollow cylindrical body 1 with a bottom, in the cylindrical part of which there is a window. Through the window into the body fit the liners 2 and absorbers 3-8. The window is closed with a lid 9 and an insert 10. The liners and absorbers are tightly pressed to the bottom of the housing with an inverse diffuser 11. The return diffuser 11 adjoins to the support post 12 through an elastic gasket 13. The ionization volume is formed by the cavity of the liner 2, which is pressed to the absorber with an end face, the insert has a cylindrical a blind hole in which the collecting electrode 14 is placed.

The device works as follows.

The bundle enters through the bottom of the hull.

When passing through the irradiated material, gas is ionized in the air cavities. Ionization of gas in air cavities with a collecting electrode is measured using an electrometric device. The total energy loss of bremsstrahlung consists of ionization and radiation losses.

As a result of interaction with the substance of the medium, the radiation flux density decreases. The energy flux density is measured by the method of a thick-walled ionization chamber, i.e., by measuring the specific ionization in the cavities of the chamber and the calculated sensitivity value.

Having in the graphite and aluminum block several ionization cavities with thicknesses of the front walls for which the sensitivity was calculated, several values of the energy flux density can be obtained that relate to the front surface of the bottom of the housing. The experimental conditions and the geometry of the experiment remain unchanged. The obtained values of the energy flux density are averaged.

Several inserts alternating with absorbers form many ionization chambers with different thicknesses of the front walls, which makes it possible to measure the ionization current at any depth. In this design, the front wall thickness for each of the ionization chambers is formed by the sum of liners and absorbers measured along the axis of the housing and located in front of the chamber.

The mass of impurities in the working area of the chambers, taking into account the masses of gas in the air gaps between the absorbers and liners, is reduced compared with the prototype, which improves the measurement accuracy and simultaneously reduces the time spent on. measurements.

Claims (1)

Claim Device for measuring the flux density of energy of bremsstrahlung, containing a hollow body of the chamber with a bottom and replaceable absorbers, characterized in that, in order to improve the accuracy of measuring the density of the flow of energy of bremsstrahlung and reduce measurement time, the camera body is made in the form of a hollow cylinder with a flat bottom, cantilever-mounted on a support post, inside the case there are successively located inserts with blind holes, absorbers and a return diffuser with an external cross-section diameter equal to the internal diameter The meter body, while the liners, absorbers and the return diffuser are tightly pressed to the bottom of the housing and to each other, with the housing with the bottom, absorbers, liners and the return diffuser made of the same, uniform material, such as graphite or aluminum, and the distance from the bottom of the liner opening located in front of the return diffuser, to the support column is chosen not less than the mean free path of the electron with the maximum energy in the spectrum.