Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
  • G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators
  • G21K1/067—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators using surface reflection, e.g. grazing incidence mirrors, gratings
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
  • G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
  • G21K1/025—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K2201/00—Arrangements for handling radiation or particles
  • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
  • G21K2201/067—Construction details

Definitions

• the invention relates to a lens for high-energy radiation according to claim 1, its use according to claim 6 and methods for its production according to claims 7, 9 and 10.
• the described embodiment consists of a bundle of 2000 glass capillaries with a inner diameter of 0.36 mm (360 ⁇ m) and a length of 98 cm, which are bent in the direction of the axis of the bundle.
• the lenses mentioned have in common that long reflecting systems are required for focusing X-rays and particle radiation.
• the overall length of the lenses in the beam direction for the Kumakhov lens is approximately 1 m;
• the lens systems used for astronomy have similar lengths.
• the known lenses are expensive because of their size and the complex surface processing.
• the capillaries used for the Kumakhov lens must have a highly precise inner surface due to the multiple beam reflection in order to keep intensity losses in a still acceptable range.
• a Kumakhov lens with a quality that approximately corresponds to the theoretically given possibilities has not yet been produced.
• the object of the invention is to propose a lens for high-energy radiation which has a very small length in the beam direction. Furthermore, the lens should be simple and inexpensive to manufacture.
• the object is achieved according to the invention by the lens described in claim 1.
• the use of the lens is the subject of claim 6.
• Methods for producing the lens are specified in claims 7, 9 and 10.
• the dependent claims describe preferred configurations of the lens and a method for its production.
• the disc is curved in such a way that it has a concave and a convex side.
• the disk can be curved in such a way that it forms part of the circumferential surface of a cylinder, so that its cross-section forms part of a circle, e.g. B. represents a third or fourth of a circle.
• the channels point to a common line, namely the axis of the cylinder.
• the disk is curved in such a way that all the channels point to a common point, the focal point.
• the concave side forms a radially symmetrical depression, while the convex side represents a corresponding elevation.
• the disk is preferably curved in such a way that the tangent at its edge encloses an angle between 3 ° and 20 ° with the tangent surface at its apex. This angle was derived from a polycarbonate lens.
• the lens according to the invention is only permeable to radiation of a single energy range. Other energy areas are focused when the degree of curvature is changed.
• a lens which is composed of a planar pane which has a center appears to be equally suitable as a lens, the channels running perpendicular to the plane of the pane and the channels form an angle outside the center with the channels in the center, the amount of which increases as the channels are distant from the center. Also such Before an embodiment forms a lens with channels which point to a common line or a common point on one side of the lens.
• the thickness of the pane can be chosen to be very small. In any case, a thickness of 1 cm is sufficient.
• the exemplary embodiment shows that focusing is also achieved with a curved disc, the thickness of which is less than 1 mm.
• the number of channels and their diameter determine the permeability of the lens for the radiation to be focused.
• the absorption of radiation falling on the lens depends on the total ratio of the areas of the open and the closed areas. The higher the total area of the channel inlet openings and thus the open areas, the more permeable the lens is.
• the channels should have a diameter of less than 50 ⁇ m. Smaller diameters, approximately 10 ⁇ m and less, appear to be more suitable. Optimal properties are expected with a channel diameter of less than 1 ⁇ m, approximately 0.1 ⁇ m. In order to reduce the absorption of the radiation by the radiopaque material of the pane, the number of channels must be increased accordingly.
• One embodiment of the lens according to the invention can be based on a planar, for the respective type of radiation Create permeable pane.
• the planar disk is provided with a multiplicity of continuous, mutually parallel channels which run perpendicular to the plane of the planar disk and measure a maximum of 50 ⁇ m in diameter.
• a large number of very fine channels can be produced by exposing the planar disk to a parallel ion beam incident perpendicularly on the planar disk, which penetrates the planar disk.
• the arrangement of the individual channels is arbitrary; a specific pattern need not be specified.
• planar disks with a plurality of channels which are parallel to one another and run perpendicular to the disk plane are already commercially available for the purpose of filtering liquids.
• Suitable for producing a lens for soft X-rays have been found, for example: B. filter plates made of polycarbonate with a variety of pores between 12 and 0.015 microns, as they are offered under the name "Nucleopore R polycarbonate membrane” in specialist shops. These filter plates have a thickness of significantly less than one millimeter.
• the planar disk is curved in the manner specified above.
• the curvature can e.g. B. with the help of a stamp in a form, the surfaces of the stamp and shape correspond to the desired curvature.
• the filter plates mentioned can be inserted into an opening in an evacuable container, after which the container is permanently evacuated by a pump.
• the filter plate bulges symmetrically in the direction of the interior of the container, the degree of curvature depending on the pump power.
• a self-supporting planar glass or plastic pane perforated by channels can be permanently arched at an increased deformation temperature.
• the lens should not have a focal point, but a focal "line", it is sufficient with flexible planar disks, the planar disk in the Way in a fixing and tensioning device that they z. B. forms part of the outer surface of a cylinder.
• part of a ball surface z. B. made of thin glass and an approximately point-shaped particle source is fixed in the center of the sphere, the energy of the particles being sufficient to penetrate the material.
• An analog method can be used to manufacture planar lenses. A flat disk with a center point is irradiated with the aid of an approximately point-shaped particle source. The particle source is arranged on a line that runs perpendicular to the flat disk through its center. ⁇ radiation is particularly suitable as particle radiation.
• the lens according to the invention can also be used analogously to the known lens systems to generate a parallel bundle of rays.
• a point-shaped radiation source can be arranged in the focal point of the lens.
• Fig. 1 shows the experimental arrangement with the help of which the experiments described below were carried out.
• the experimental arrangement consists of a device 1 for emitting soft X-rays, the lens 2 and a PIN detector (PIN diode) 3 for determining the intensity of the X-rays. lung.
• the device 1 consists in a known manner of an anode 4 and a cathode 6, which are separated from one another by a dielectric 5.
• An adjustable high voltage 8 with U> 10 to 20 kV is applied to the anode 4 and the cathode 6.
• the cathode 6 forms an aperture with a diameter of 10 mm. Point 7 is approx. 50 mm from the aperture.
• the test arrangement is kept under a pressure of P ⁇ 10 -3 mbar.
• the intensity of the X-rays emitted by the device 1 depends on the material of the anode 4 and cathode 6, their geometry and the voltage applied.
• a filter plate is used as lens 2, which is commercially available under the name "Nucleopore R polycarbonate membrane".
• the filter plate consists of a planar disc with a diameter of 4.5 cm and a thickness of 0.01 mm. The manufacturer states that the pore diameter is 10 ⁇ m and the pore density is 1 ⁇ 10 5 pores / cm 2 . The pores represent continuous channels.
• the filter plate is curved using a holding device (not shown), the degree of curvature being adjustable. In all cases, the curvature is such that the filter plate has a continuously curved line in cross section. Instead of a focal point, a focal "line” is obtained with a curvature that is circular in cross-section and is designated by "F".
• a small edge section of the lens was clamped.
• the lens 2 was fixed laterally by a wire bracket.
• the edge section opposite the clamped edge section was held by a further wire bracket which could be displaced with the aid of a micrometer screw in the direction of the clamped edge section, so that the lens 2 could be arched to an increasing extent by screwing in the micrometer screw.
• the positions can be set from 0 mm to 8 mm become.
• the 8 mm position corresponds to a very slightly curved lens.
• Fig. 2 shows schematically the filter plate in planar form in plan view (part a) and cross-sectional representation (part b) and in a curved form (part c).
• the curvature corresponds to the case mentioned above and shown in the figure (part c) that the curved filter plate lies on the lateral surface of a cylinder. In the other positions, a more or less strong curvature is achieved.
• the extensions of the channels do not point exactly to the line labeled "F" because a reflection takes place on their inner surface.
• the beam deviation due to the reflection can be neglected for practical purposes.
• the rays ⁇ n are therefore focused at very small channel diameters on the common line (the cylinder axis) on which the extensions of the channels intersect on the concave side of the filter plate.
• the focal point of the radiation is closer to the lens than the intersection of the extensions of the channels, as can be derived from part c of the figure.
• FIG. 3b shows a diagram analogous to FIG. 3a with the test arrangement largely unchanged.
• the device 1 contained both an iron cathode and an anode. Again, a horizontal line was obtained without lens 2 in the diagram. In the experiment with lens 2, the intensities obtained were designated with the error bars.
• the focusing effect with lens 2 can be seen in the maxima of the intensity at a low position Q of the micrometer screw (stronger lens curvature).
• the low intensity values in the case of a slightly curved lens 2 again appear to be due to the absorption of the radiation by the lens 2.
• a stronger curvature (Q in the range between 1 and 3 mm) gives intensity values which are clearly above the intensity values which are obtained without lens 2 (horizontal line).
• the maxima are interpreted as the X-ray spectrum of the X-rays emitted by the iron cathode.
• FIG. 4a shows a further intensity diagram.
• the distance between lens 2 and PIN diode 3 in the beam direction (cf. FIG. 1) was 220 mm.
• Both electrodes were made of iron, but had a different geometry, so that an X-ray radiation with a higher intensity was obtained overall.
• the above-mentioned PIN diode 3 was used.
• the lens 2 was curved in such a way that Q (position of the micrometer screw) was 2.8 mm and kept constant at this value. In contrast, the position of the PIN diode was varied.
• FIG. 4b shows the results obtained without lens 2 with the same arrangement. This attempt shows the unaffected beam contour perpendicular to the beam path. The maximum of the intensity is lower than the maximum of the intensity which is obtained with the lens 2 inserted.
• FIG. 5 shows a further intensity diagram.
• Both the cathode and anode of device 1 were made of iron.
• Three maxima were obtained with lens 2, while a horizontal line resulted without lens.
• the maxima are interpreted analogously to the results shown in FIG. 3b as an X-ray spectrum of the iron cathode of the device 1.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Analysing Materials By The Use Of Radiation (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1994
  • 1994-10-27 DE DE4438362A patent/DE4438362C2/de not_active Expired - Fee Related
• 1995
  • 1995-09-23 EP EP95935371A patent/EP0788652A1/de not_active Withdrawn
  • 1995-09-23 JP JP08514277A patent/JP3095779B2/ja not_active Expired - Fee Related
  • 1995-09-23 WO PCT/EP1995/003776 patent/WO1996013840A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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