SU137195A1 - Lighting system for liquid hydrogen bubble chambers - Google Patents

Description

Many lighting systems for liquid hydrogen bubble chambers are known. For example, a lighting system is known with a spherical mirror and louvre, in which a light source is installed in the center of curvature of the spherical mirror. Therefore, the rays of light, reflected from the mirror, return to the light source. To eliminate the possible photographing of imaginary images of tracks (images of traces of charged particles) resulting from reflection of rays scattered by bubbles from a mirror, a louvre system is used, which is a collection of thin metal plates, each of which has a certain angle of inclination to the axis of the mirror. . The disadvantages of this system are the difficulty of adjusting the louvre, associated with the requirement to install each plate at a certain angle to the mirror axis, a large number of these louvers and, moreover, hydrogen boiling occurs on the ribs of the louvres, which is highly undesirable. A focusing raster lighting system is also known. The elements of the raster system, which are double-curvature hemotoric rings, are installed on the spherical bottom of the chamber, the radius of curvature of which is equal to the radius of curvature of the raster element in the sagittal section. The side surfaces of the raster elements are blackened. A mirror layer is applied on the rear cylindrical surface of each raster element, therefore, a set of light rays coming from a source located in the center of the curvature of the spherical bottom of the chamber returns to the source. The most significant disadvantage of this system is the small thickness of the raster element, which leads to a significant number of such elements and makes it difficult to adjust the system. In addition, a change in the height of a raster element leads to a defocusing of a beam of light rays reflected from the mirror layer of the raster.

No. 137195- 2 -

The proposed lighting system for liquid bubble chambers containing a raster differs from the known ones in that each raster element is made of several plane-parallel plates with opaque joints. The thickness of the raster elements is chosen because of the elimination of possible photographing of imaginary images of traces of charged particles. The light source is placed in the meridional focus of the refractive surface of each raster element and at the same time in the center of curvature of the saggital sections of all raster elements. Distinctive features of the proposed lighting system make it easier to align the system, eliminate the possibility of races, focusing the light beam, and reduce the number of raster elements.

FIG. I shows the meridional and saggittal sections of the raster element; in fig. 2 - one raster element; in fig. 3 - meridional and sagittal sections of the chamber.

The light source is placed in the meridional focus F (Fig. 1) of the refracting surface, the radius r of which is curved in the meridional section

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where: H is the focal distance of the refractive surface in the meridional section or the height of the chamber; p is the refractive index of the material of the raster element; n is the refractive index of liquid hydrogen in the working state. A reflecting mirror layer is applied on the rear cylindrical surface of each raster element. Each raster element is made of several plane-parallel plates 2 with opaque joints 3, which play the role of blinds. If the light source is placed in the meridional focus (Fig. 1) of the refractive surface of each raster element and at the same time in the center of the curvature of its sagittal cross section, then the rays falling on the raster element return to the light source after reflection from the cylindrical mirror surface. Since the raster elements (Figs. 2 and 3) are mounted on the spherical bottom of the camera, in the center of the curvature of which the light source is located, they all work under the same conditions.

The thickness D of each raster element is determined from the condition of the absence of rays that fall into the photographic lenses 4 after reflection from the raster refracting surface. The height h of each raster element is selected from structural considerations, and the thickness of each of the plates (louver pitch) is determined from the absence of imaginary images of the tracks. Since the thickness D of each raster element in the described lighting system is relatively large, the required number of raster elements is small, which greatly facilitates the alignment of the system. The role of the louver s of the described system is played by opaque junction surfaces of the plates, and, naturally, hydrogen boiling does not occur at their edges. The change in the height h of the raster elements (due to the manufacturing error, the effect of temperature) does not cause the light beam to defocus in the system described, since in the meridional section the plane parallel beam remains perpendicular to the reflecting layer.

Subject invention

The illumination system of liquid hydrogen bubbles of chambers containing rasters, a source of light, characterized in that, in order to facilitate system alignment, eliminate defocusing of the light beam and reduce the number of rasters, each raster element is made of several plane-parallel plates with opaque joints, the thickness of which from the condition of eliminating the photographing of imaginary images of traces of charged particles, and the light source is placed in the meridional focus of the refractive surface of each raster element and simultaneously in the center of curvature of the sagittal sections of all elements of the raster.

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