A NUCLEAR TARGET, METHOD FOR INDUCING A NUCLEAR REACTION AND A DEVICE SUITABLE FOR CARRYING OUT THE METHOD

Abstract

The present invention relates to a nuclear target (1), a method for inducing a nuclear reaction and a device capable of inducing nuclear reactions. According to the present invention, the nuclear target (1) is equipped with a hollow (12) into which projectile particles (3) are deposited. In the hollow (12), the projectile particles (3) interact with precursors (21 and/or 22 and/or 23), or projectile particles (3) are elastically scattered on isotopes (4). The nuclear target (1), method, or the device thus provides a more efficient induction of nuclear reactions and provides a higher yield of radioisotope production. In another embodiment, the nuclear target (1) can be used as a means used to nuclear waste transmutation, or as a means of sustainable exothermic nuclear reactions.

Claims

1. A nuclear target forming a bulk, wherein the nuclear target comprises at least one precursor capable of inducing a nuclear reaction upon interaction with a projectile particle, wherein the nuclear target comprises: at least one opening for the passage of a beam of projectile particles; and a hollow in the bulk of the nuclear target located behind the opening, wherein the hollow comprises and/or is formed and/or is surrounded by the precursor; and wherein the nuclear target comprises at least one isotope on which the projectile particle is elastically scattered.

2. The nuclear target according to claim 1, wherein the isotope on which the projectile particle is elastically scattered is: isotope being different nuclei from the nuclei of the precursor; or isotope being the same nuclei as the nuclei of the precursor, wherein the impinging projectile particle has kinetic energy, which differs over the threshold energy for induction of the nuclear reaction.

3. The nuclear target according to claim 1, wherein at least part of the nuclear target is formed by the precursor surrounding the hollow and/or comprises the precursor in the hollow.

4. The nuclear target according to claim 1, wherein the nuclear target comprises at least two same precursors or different precursors differently located therein.

5. The nuclear target according to claim 1, wherein the nuclear target consists of two isotopes, wherein the first isotope is the precursor and the second isotope is the isotope on which the projectile particle is elastically scattered.

6. The nuclear target according to claim 1, wherein the nuclear target is further equipped with a laser target capable of emitting projectile particles after interaction with laser radiation.

7. The nuclear target according to claim 1, wherein the inner side of the hollow is provided with a layer of the material and/or the hollow comprises the material emitting secondary projectile particles in the case of interaction of a projectile particle or another particle produced by the interaction in the hollow.

8. The nuclear target according to claim 1, wherein the nuclear target is provided with a plurality of openings and a corresponding number of hollows.

9. The nuclear target according to claim 1, wherein the nuclear target contains isotopes selected from nuclei having threshold of inelastic scattering with the nuclei of projectile particles or precursor, or the nuclei of the products of the reactions of projectiles with precursors is higher than the energy of the interacting nuclei.

10. The nuclear target according to claim 1, wherein the opening and/or a part of the hollow is provided with luminophore or scintillator.

11. The nuclear target according to claim 1, wherein the nuclear target consists of plurality of segments configured so that, the segments form a single bloc of material, wherein the shape of the hollow is configured for suppression of scattering of the projectile particles outside an area of the hollow.

12. A method for inducing a nuclear reaction comprising the steps of: providing a beam of projectile particles impinging on the nuclear target according to any one of the preceding claims; wherein the beam of projectile particles is focused into the hollow of said nuclear target; wherein the projectile particles are elastically scattered on the nuclei of at least one isotope inside the hollow of the nuclear target until the projectile particles interact with the precursor.

13. The method for inducing a nuclear reaction according to claim 12, wherein the projectile particles are generated by a laser-driven accelerator.

14. A method for producing radioisotopes, wherein the method comprises the method for inducing a nuclear reaction according to claim 12, wherein the projectile particle is selected from the group p, d, n and the precursor is selected from the group .sup.2H, .sup.3H, .sup.10B and/or .sup.11B or NatB, .sup.99Mo, .sup.186W,.sup.185Re, .sup.187Re or a natural mixture of .sup.NatRe.

15. A method for nuclear waste transmutation, wherein the method comprises the method for producing radioisotopes according to claim 12, wherein the projectile particle is selected from the group consisting of p, d, n and the precursor is selected from nuclear waste products.

16. A method for inducing an exothermic nuclear reaction, wherein the method comprises the method for inducing a nuclear reaction according to claim 12, wherein the nuclear reactions are selected from the group: .sup.3He(d,p).sup.4He, .sup.6Li(d,?).sup.4He, .sup.7Li(p,?).sup.4He, .sup.10B(p,?).sup.7Be, .sup.11B(p,2?).sup.4He, .sup.15N(p,?).sup.12C, .sup.6Li(p,.sup.3He).sup.4He followed by secondary reactions .sup.6Li(.sup.3He,2?).sup.1H and .sup.3He(.sup.3He,2p).sup.4He, .sup.3H(d,n).sup.4He, .sup.2H(t,n).sup.4He, .sup.2H(n,?).sup.3H, .sup.6Li(n,.sup.3He).sup.4He, .sup.10B(n,?).sup.7Li .sup.7Be(n,p).sup.7Li .sup.13C(n,?).sup.14C, .sup.14N(n,p).sup.14C, .sup.17O(n,?).sup.14C, .sup.21Ne(n,?).sup.18O, .sup.22Na(n,p).sup.22Ne or .sup.37Ar(n,?).sup.34S.

17. A method for recovering heat from an exothermic nuclear reaction, wherein the method comprises the method of claim 15, wherein the heat is conducted to a heat exchanger.

18. The method according to claim 12, wherein the projectile particles emitted from the laser target are sequentially impinging into the hollow of the nuclear target by weight and/or mass-to-charge ratio of the projectile particle.

19. A device suitable for the production of radioisotopes, wherein the device comprises a source of projectile particles adjustable so that the projectile particles fall on the hollow of a nuclear target, wherein the nuclear target is the nuclear target according to claim 1.

20. The device suitable for the production of radioisotopes according to claim 14, wherein the device comprises a laser target capable of emitting projectile particles after being struck by a laser pulse, wherein the laser target is placed in front of the opening of the nuclear target so that the emitted projectile particles fall into the hollow of the nuclear target.

Description

DESCRIPTION OF THE DRAWINGS

[0052] FIGS. 1a-1f are schematic illustrations of the first embodiment of a nuclear target according to the present invention in various alternatives of precursor placement in the target.

[0053] FIGS. 2a and 2b are schematic illustrations of the second preferred embodiment of a nuclear target according to the present invention with the first and second part of the hollow.

[0054] FIGS. 3a, 3b and 3c are schematic illustrations of another preferred embodiment of a nuclear target according to the present invention comprising a laser target capable of generating projectile particles, wherein FIG. 3b illustrates a more preferred embodiment with an inset laser target, FIG. 3c illustrates a preferred embodiment comprising a precursor in a liquid or gaseous form, where the precursor is contained in the hollow of the nuclear target.

[0055] FIG. 4 is a schematic illustration of an embodiment of a nuclear target hollow according to the invention, wherein the hollow is equipped with a layer emitting secondary projectile particles upon interaction with the primary projectile particle.

[0056] FIG. 5 is a schematic illustration of an embodiment of a continuous band provided with nuclear targets according to the present invention.

[0057] FIGS. 6a and 6b are schematic illustrations of an embodiment of a nuclear target provided with a luminophore.

[0058] FIG. 7 is a schematic illustration of an embodiment of a nuclear target in combination with a heat exchanger.

[0059] FIGS. 8a-8e illustrate different embodiments of a nuclear target hollow geometry according to the invention.

[0060] FIGS. 9a and 9b are schematic illustrations of a device comprising a laser-controlled accelerator generating projectile particles comprising a nuclear target according to the invention.

[0061] FIGS. 10a and 10b are schematic illustrations of the nuclear target according to the present invention used in an experiment.

[0062] FIG. 11 represents post-experimental analysis of the hollow of the nuclear targets #1, #2 and #6 according to the present invention.

[0063] FIG. 12 represents post-experimental analysis of the height profile of the nuclear targets #1, #2 and #6 according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] Radioisotopes are produced by bombarding or irradiating a nuclear target 1 comprising precursor(s) 21 or 22 and/or 23. Precursor 21 and/or 22 and/or 23 refers to, and is generally known in the art, an atomic nucleus that interacts with a projectile particle 3 to achieve the final product. The final product is often an unstable radioisotope that further decays by alpha, beta and/or gamma decay. The generation of products by induced nuclear reactions according to the present invention takes 50 place substantially inside the hollow 12 of the nuclear target 1, wherein at least a portion of the precursors 21 and/or 22 and/or 23 present/comprised in the hollow 12 interact with projectile particles 3 and form the final product by nuclear reactions. In most cases, the product formed, most often a radioisotope, is consequently mixed with another material forming the nuclear target 1, wherein the untransformed precursor 21 and/or 22 and/or 23 remains randomly distributed in said nuclear target 1. Certain portion of the converted precursors 21 and/or 22 and/or 23 to the final product(s) can be separated using chemical methods. An example of a chemical method for separating converted radioisotopes consists in dissolving the nuclear target 1, or the content of the hollow 12 of the target 1, in a strong acid, followed by filtration of radioisotopes and precipitation thereof.

[0065] The nuclear target 1 according to the present invention comprises at least one nucleus of the precursor 21 or 22 in the envelope of the nuclear target 1 and/or the precursor 23 inside the hollow 12, which is transformed into the product nucleus by the nuclear reaction; and an isotope 4 on which the projectile particle 3 is elastically scattered until the interaction with the nucleus of the precursor 21 and/or 22 and/or 23. In the case of the example according to FIG. 1a-f, the precursor 21 and/or 22 or the precursor 23 itself can be the isotope 4 until the kinetic energy of the projectile particle 3 equals the energy of a reaction channel. Examples of such materials may include, for example, .sup.10B as the nucleus of the precursor 21 and/or 22 and/or 23, p,?s the projectile particle 3, wherein the isotope 4 on which the projectile particle 3 is elastically scattered is one of the stable isotopes 4 W (.sup.180W,.sup.182W,.sup.183W,.sup.184W,.sup.186W; or a natural mixture thereof, in accordance with FIG. 1a), and wherein the resulting nuclear reaction is .sup.10B(p,?).sup.7Be. In another example, .sup.11B(p,?).sup.8Be can be selected, wherein .sup.8Be further decays according to .sup.8Be .fwdarw.2?, with the W isotopes 4 being used as nuclei on which the projectile particles 3 are elastically scattered. Another example may include a nuclear reaction of .sup.98Mo(p,n).sup.99mTc, wherein the isotopes 4 on which the projectile particles 3 are elastically scattered are W isotopes 4 forming the envelope of the nuclear target 1. In another embodiment, it is possible to place the precursor 21 or 22 into the body of the nuclear target 1, for examples, as part of the envelope of the hollow 12 (FIGS. 1a, 1b, 1d, 1e and 1f), and/or place it in the hollow 12 of the nuclear target 1 (FIGS. 1c, 1d, 1e and 1f). It is also possible to combine the above placements of the precursors 21 and/or 22 and/or 23b as schematically illustrated in FIG. 1d-1f.

[0066] According to another example of an embodiment, the nuclear target 1 may contain a natural mixture of boron, i.e. 20% of .sup.10B and 80% of .sup.11B, as the nuclei of the precursor 21 and/or 22 and/or 23. FIG. 1 a schematically illustrates the ordered distribution of the precursors 21 corresponding in cross-section to the circles. In this embodiment, the respective precursors 21 can be implanted into the body of the nuclear target 1 using various chemical-physical processes such as chemical or physical vapour deposition (CVD or PVD, respectively). FIG. 1b schematically illustrates a situation where the precursor 22 is deposited in a defined area and forms a bulk of a material with a hollow 12. FIG. 1c illustrates an embodimentwhere the precursor 23 is placed directly into the hollow 12 of the nuclear target 1, i.e. the precursor 23 is not implanted in the material of the nuclear target 1, but is placed in a part of the hollow 12 of the nuclear target 1 and is used as a fill in the hollow 12. The precursor 22 can also be placed directly into the hollow 12 of the nuclear target 1 using known methods of PVD, CVD or ion implantation or as a bulk of the material. FIG. 1d schematically illustrates a possible combination of the placement of the two precursors 22 and 23. Similarly, it is possible to provide an embodiment according to FIG. 1e, where precursors 21 and 23 are present, wherein the first precursor 21 forms part of the material bulk. The second precursor 23 is placed in the hollow 12. The first and second precursors 21 and/or 22 and 23 according to FIG. 1f can be the same isotope. In another embodiment, the isotopic composition of the first and second precursors 21 and/or 22 or 23, respectively, differs according to FIG. 1f. The preferred embodiment according to FIG. 1d-1f can be used in particular in the field of heat production by means of a fission nuclear reaction. In this preferred embodiment, the nuclear target 1 may comprise in the envelope precursors 21 and/or 22 containing, for example, the isotopes .sup.233U, .sup.235U and .sup.239Pu. At the same time, the nuclear target 1 comprises a 55 hollow 12, which is filled with the precursor 23, serving at least partially as a fill. The second precursor 23 may be .sup.3H or LiD to emit neutrons capable of initiating a fission nuclear reaction onto the precursor 21 and/or 22 when interacting with the projectile particle 3. Finally, exothermic nuclear reactions occur as a result of interactions of the above-selected precursors 21 and/or 22 and 23 with the projectile particles 3.

[0067] In another embodiment, the nuclear target 1 can be enriched, for example a target having .sup.10B with up to 90% in concentration, thereby inducing an appropriate reaction scheme according to the nuclear reaction mentioned above. It is also possible to select the distribution of precursors 21 and/or 22 and/or 23, e.g. a higher concentration of precursors 21 and/or 22 and/or 23 at the edges of the nuclear target 1 in accordance with its intended use. It is also possible to use two types of precursors 21 and/or 22 and/or 23, or a simultaneous placement, for example, the arrangement according to FIG. 1d-1f.

[0068] The nuclear target 1 may be substantially of a planar shape, being provided with an opening 11 and a hollow 12 in a bulk of material located behind the opening 11. The hollow 12 can take any shape. FIGS. 1a-1d illustrate schematic cross-sections of the nuclear target 1, where a part of the cross-section of the hollow 12 corresponds substantially to the shape of a circle. In another embodiment, e.g. according to FIGS. 8, the cross-sectional shape of the hollow 12 may correspond to a section of an ellipse, rectangle, mushroom or polygon with a tapered opening 11. However, the nuclear targets 1 always comprise openings 11 for projectile particles 3 to pass into the hollow 12 of the nuclear target 1.

[0069] In the preferred embodiment schematically illustrated in FIG. 2?, the hollow 12 can be formed of two parts. The first part 121 represents a narrower part of the hollow 12 through which the projectile particle 3 passes. In the second part 122 of the hollow 12, which is more voluminous than the first part 121, the projectile particle 3 is deposited and elastically scatters on the nuclei of isotopes 4 or induces a nuclear reaction on a particular precursor 21 and/or 22 and/or 23. The advantage of the narrower part 121 of the hollow 12 of the nuclear target 1 is to minimize backscattered particles 31 emanating from the nuclear target 1 outside the area of the hollow 12.

[0070] Another advantage of the hollow 12 having parts 121 and 122 is characterized in that it is not necessary for the beam 3 of projectile particles 3 to be focused perpendicularly to the nuclear target 1. The beam of projectile particles 3 can be deposited into the hollow 12, e.g. according to FIG. 2b under particular angle. The elastic scattering of the projectile particles 3 in the hollow 12 ensures a sufficient amount of trapped projectile particles 3 to induce a sufficient number of nuclear reactions on the precursors 21 and/or 22 and/or 23.

[0071] The opening 11 of the nuclear target 1 serves for the entry of projectile particles 3, such as protons, deuterons, light nuclei, which can be accelerated in commonly used particle accelerators. In another embodiment, laser-controlled accelerators may be used. In another embodiment, a collimated beam of projectile particles 3 from static emitters, such as AmBe, RaBe or PuBe, can also be used. In the case of neutrons used as projectile particles 3, it is also possible to use spallation sources or a collimated beam of neutron coming from a fission reactor. The projectile particles 3 pass through the opening 11 of the nuclear target 1 and are deposited in the cavity 12 thereof. Ideally, there are exactly two possible interactions occurring in the hollow 12. The first interaction consists of the induced nuclear reaction of the projectile particle 3 with the precursor 21 and/or 22 and/or 23, wherein the projectile particle 3 and the precursor 21 and/or 22 and/or 23 are suitably selected according to the industrial application. In the latter case of the desired interaction, the projectile 50 particles 3 are elastically scattered on the isotopes 4, wherein the kinetic energy of the projectile particles 3 is dissipated until the projectile particle 3 interacts with the desired nuclear reaction selected from possible interaction channels and a nuclear reaction occurs on the precursor 21 and/or 22 and/or 23.

[0072] The volume of the nuclear target 1, the thicknesses of the walls of the nuclear target 1, the size and shape of the hollow 12, the distribution of the precursors 21 and/or 22 and/or 23, and other commonly needed parameters of the nuclear target 1 are appropriately selected according to the desired nuclear reaction and relevant industrial application. Commonly used computer programs can be used to determine the above parameters.

[0073] The final product of the reaction of the projectile particles 3 with the nuclei of the precursor 21 and/or 22 and/or 23 may be, for example, radioisotopes used in radiation therapy, radioisotopes used for imaging in medical applications and/or diagnostics of materials. In another embodiment, the final product may be a stable isotope 4 having a short and/or medium half-life. In another embodiment, the final product may be a stable isotope 4 made in exothermic nuclear reaction, which can then be converted to heat 9 in a heat convertor 91.

[0074] In the embodiments according to FIGS. 3a and 3b, the nuclear target 1 may be further equipped with a laser target 5 comprising a layer 50 emitting projectile particles 3, if the reare side 51 of the layer 50 is exposed to laser beams. Thus, a beam of accelerated projectile particles 3 is emitted from the layer 50, which can be used to induce nuclear reactions in the hollow 12 of the nuclear target 1 according to the present invention. In the embodiment shown in FIG. 3a, a laser target 5 provided with a layer 50 is tightly placed in front of the opening 11 of the nuclear target 1. After being struck by the laser pulse 52, projectile particles 3 are emitted directly into the hollow 12 of the nuclear target 1, where they induce a nuclear reaction or are elastically scattered. Emission of projectile particles 3 can be provided using the TNSA mechanism (M. Roth, M. Schollmeier. Ion Acceleration-Target Normal Sheath Acceleration. Vol. 1 (2016): Proceedings of the 2014 CAS-CERN Accelerator School: Plasma Wake Acceleration, DOI: https://doi.org/10.5170/CERN-2016-001.231). In another embodiment, shown in FIG. 3b, the laser target 5 can be placed to the hollow 12 of the nuclear target 1 inset in front of the opening 11 to accelerate the projectile particles 3 into the hollow 12 of the nuclear target 1. The advantage of the inset between the laser target 5 and the opening 11 of the nuclear target 1 provides the possibility of placing a vacuum pump 6, which sucks out the impurities emitted from the laser target 5, under the influence of the laser pulse 52 and the use of the laser wake field acceleration. A preferred embodiment also presents an offset of the laser target 5 with the layer 50, providing shielding between the electromagnetic pulse of the laser radiation and the nuclear target 1, in case, in which the material of the nuclear target 1 is electrically conductive. In case the projectile particles 3 represent a mixture of isotopes 4, the inset makes it possible to configure the time sequence in which the projectile particles 3 will hit the precursor 21 and/or 22 and/or 23 and interact with it, or with the products of the interactions of the previous wave of projectile particles 3 with the precursor 21 and/or 22 and/or 23. Such an exemplary embodiment with a time sequence of the incidence of projectile particles 3 into the hollow 12 can be taken from Torrisi, Lorenzo & Cavallaro, Stefano & Cutroneo, M. & Krasa, Josef & Klir, Daniel. (2014). D-D nuclear fusion induced by laser-generated plasma at 10.sup.16 W cm.sup.?2 intensity. Physica Scripta. 2014. 014026. 10.1088/0031-8949/2014/T161/014026. The sequence of the incident projectile particles 3 and the interaction with the precursors 21 and/or 22 and/or 23 is provided by more complex laser target 5 configurations, such as the catcher-pitcher reported in D. Margarone, et. al. (2020). Generation of ?-Particle Beams With a Multi-kJ, Peta-Watt Class Laser System. Frontiers in Physics, September 2020, Vol B, Article 343.

[0075] Preferred embodiments provided with a laser target 5 are capable of providing a high-energy beam of hadron particles, such as protons, light nuclei, heavy nuclei (e.g. Au) 50 or neutrons, but also an electron beam without the need for complex beam-transport. The preferred embodiment illustrated in FIG. 3b, inter alia, enables the use of laser-controlled accelerators, which are generally considered as a more compact and cheaper option to conventional accelerators.

[0076] FIG. 3c further schematically illustrates another embodiment which comprises a 55 nuclear target 1 and a laser target 5. The area between the laser target 5 and the nuclear target 1 is closed to prevent the exchange of fluids with the surrounding environment. The closed area can then be filled with a liquid or gas containing precursors 23.

[0077] In another preferred embodiment, the material of the laser target 5, structure and thickness thereof can be selected so that a suitably selected focus of the laser pulse (pulse cross-section) using the TNSA mechanism leads to the production of optimal spectrum of projectile particles, both in intensity and the energy spectrum of the particles. In a certain example of the embodiment, the isotopic composition of the nuclear target 1 is selected to consist of exactly two isotopes. The first isotope is a precursor 21 and/or 22 and/or 23, which is localized in the envelope and/or hollow 12 of the nuclear target 1. The second isotope is a nucleus on which the projectile particles 3 are elastically scattered. This embodiment provides an advantage in that immediately after the bombardment of the projectile particles 3, only the interaction with precursor 21 and/or 22 and/or 23 is allowed, or the projectile particles 3 are elastically scattered on the isotopes 4 until they interact with the nucleus of the precursor 21 and/or 22 and/or 23. In the next phase, products of ongoing nuclear reactions with projectile particles 3 may also enter the process. These may by, for instance, ions with a smaller mass-to-charge ratio, which reach the hollow 12 with a certain delay, as reported by Torrisi, Lorenzo & Cavallaro, Stefano & Cutroneo, M. & Krasa, Josef & Klir, Daniel. (2014). D-D nuclear fusion induced by laser-generated plasma at 10.sup.16 W cm-.sup.2 intensity. Physica Scripta. 2014. 014026. 10.1088/0031-8949/2014/T161/014026. Ultimately, the yield of the nuclear reaction increases.

[0078] In the example illustrated in FIG. 4, the inner side 123 of the hollow 12 of the nuclear target 1 is provided with a layer 32. The layer 32 comprises atomic nuclei that are capable of emitting secondary projectile particles 320 after interacting with the projectile particle 3. FIG. 4 represents a specific embodiment provided with a laser target 5. However, it is clear to the person skilled in the art that the technical function of the layer 32 is completely separable from the technical function of the laser target 5 and can thus be implemented, without any further technical difficulties, in any embodiment, for example according to the FIGS. 1a-1f and/or 2a, 2b, or advantageous technical effects can be combined with any of the above examples.

[0079] More specifically, for example, the technical function of the layer 32 according to the embodiment illustrated on FIG. 4 can be used and implemented in the embodiment according to FIG. 2a or 3b, i.e. it is possible to construct the hollow 12 of the nuclear target 1 of the first part 121 and the second part 122 so that the backscattered particles 31 hit the layer 32, or to provide the nuclear target 1 with the layer 32 with a laser target 5. The technical functions remain completely separable, including the advantages provided. The layer 32 is then capable of emitting additional, secondary projectile particles 320 as a result of the interaction with the primary projectile particle 3. This preferred embodiment provides a possibility of chain reaction, i.e. releasing more projectile particles 3 into the hollow 12 than originally deposited by the beam of primary projectile particles 3. Similarly, this advantage can be achieved by a suitable combination of precursors 23 in the hollow 12. For example, if the laser target 5 is made of high-density polyethylene (HDPE), there will be protons and carbon ions .sup.12C among the projectile particles 3. If hydrogen is also contained in the precursor 21 and/or 22 and/or 23 together with, for instance, .sup.11B, nuclei-protons thereof will be gradually accelerated to an energy of 150 keV and higher by secondary reactions with the projectile, thereby allowing further reactions, e.g. .sup.11B(p,2?).sup.4He. The hydrogen nuclei in the precursor 23 will also be accelerated by ?-particles formed in previous p.sup.11B reactions.

[0080] FIG. 5 illustrates a band with a plurality of nuclear targets 1 according to the present invention comprising a plurality of openings 11 and hollows 12. This embodiment represents an advantage in moving the nuclear target 1 in direction 7. If a certain number of nuclei of precursors 21 and/or 22 and/or 23 are consumed in the volume of the first hollow 12, the nuclear target 1 is moved in such a direction 7 that the beam of projectile particles 3 falls into the next hollow 12 with the unconsumed precursor 21 and/or 22 and/or 23, thereby allowing continuity of induction of the nuclear reaction.

[0081] This example can be used, for example, in the case of exothermic nuclear reactions with a heat exchanger 91 located around the nuclear target 1. Another advantage of this embodiment is characterized in that the nuclear target 1 can form an endless band which is irradiated by one source of projectile particles 3, wherein the nuclear target 1 moves in the direction 7 as necessary.

[0082] FIGS. 6a and 6b illustrate an embodiment of a nuclear target 1 which is provided with a luminophore 8 applied on the opening 11. More specifically, the outer side 110 of the opening 11 is provided with a luminophore 8. Commonly used luminophores 8, such as Gd.sub.3Ga.sub.3Al.sub.2O.sub.12:CeMg, can be used. FIG. 6 illustrates a situation, in which projectile particles 3 are generated from a laser target 5 by means of a laser-controlled accelerator, with the laser pulse 52 being focused on the laser target 5. The projectile particles 3 are emitted into the hollow 12 of the nuclear target 1, while interacting with the nuclei of the precursor 21 and/or 22 and/or 23. In one embodiment, the interaction between the projectile particles 3 and the nuclei of the precursors 21 and/or 22 and/or 23 can be an exothermic nuclear reaction. A circumstance, in which too much gas 9 is released in the hollow 12 of the nuclear target 1 as a secondary product of interactions, may also arise, or due to the not entirely optimal shape of the hollow 12, such circumstance causes a large backflow of particles against the direction of the pulse 52. As a result, parts of the inside of the hollow 12 may be torn off and emitted outwards in the direction 81. The emissions in the direction 81 do not necessarily represent atomic and/or subatomic particles, or backscattered projectile particles 31, but it may also be small particles visible to the naked eye. Luminophore 8, in the case of the above scenario, offers a safety function that is able to detect whether a part of the nuclear target 1 has torn off and fell outside the area of the hollow 12. It is also possible to use this advantageous embodiment when handling dangerous isotopes 4 such as nuclear fission products. The embodiment on FIG. 6a illustrates a luminophore 8, which may also be mixed with the precursor 23 in the hollow 12. Similarly, FIG. 6b illustrates the application of a luminophore 8, which may help optimize the intensity and energy spectrum of projectile particles 3. This puts the laser beam intentionally out of focus. If the laser is misaligned, the pulse track 52 may not optimally overlap with the opening 11. The subsequent distribution of the luminophore 8 after irradiation can be used to optimize the internal shape of the hollow 12 according to the purpose of use, e.g. optimizing the shape of the hollow 12 according to FIG. 8. FIG. 8e illustrates a preferred embodiment of a shape of a hollow 12 of a nuclear target 1, wherein the shape of the hollow 12 is optimized so that the back-scattered particles were further reflected into the hollow 12. The nuclear target 1 according to FIG. 8e is composed of several segments 13 which provide an advantage in manufacturing essentially any shape of a hollow 12 of a nuclear target 1. The individual segments 13 of the nuclear target 1 are assembled to effectively prevent the scattering of projectile particles 3 outside the area of the hollow 12. The shape of the hollow is thus optimized against possible nuclear reaction yield losses.

[0083] The above-mentioned embodiments can be combined with the preferred nuclear reactions selected in accordance with the use of the present invention. In one embodiment, a nuclear target 1 further provided with a laser target 5 can be used, for example consisting of a layer 50 of polymer (CD.sub.2).sub.n-polyethylene, where hydrogen nuclei are replaced by deuterium nuclei, e.g. according to Torris, L. and Cutroneo, M., Triple nuclear reactions (d, n) in laser-generated plasma from deuterated targets, Physics of Plasmas, vol. 24, no. 6. 2017. doi: 10.1063/1.4984997. The nuclear target 1 can be made of tungsten and is filled with precursors 21 or 22 and 23 of .sup.6LiD and/or .sup.7LiD or N.sup.atLiD. A beam of accelerated deuterons, carbon nuclei and proton admixture, which forms a beam of projectile particles 3 that is emitted from the laser target 5 towards the hollow 12 of the nuclear target 1. The projectile particles 3 collide with the 55 nuclei of the precursor 21 and/or 22 and/or 23 contained in the hollow 12 of the nuclear target 1. This induces the respective nuclear reactions inside the hollow 12 of the nuclear target 1, which in the case of the D-D and Li-D (.sup.7Li(d,n).sup.8Be) reactions produce neutrons. The projectile particles 3, which do not collide with the nuclei of the precursor 21 and/or 22 and/or 23, are elastically scattered on the isotopes 4, or on the nuclei of the products of the occurred reactions of the projectile particles 3 with the precursor 21 and/or 22 and/or 23 until the respective nuclear reaction occurs on precursor 21 and/or 22 and/or 23.

[0084] In another example, the laser target 5 may consist of a layer 50 of HDPE. According to this example, accelerated projectile particles 3, protons, are generated from the laser target 5, leading to an induced nuclear reaction with the precursor 21 and/or 22 and/or 23 in the form of, for instance, powdered amorphous .sup.10B and/or .sup.11B or N.sup.atB. In this example, the following reactions are possible: .sup.11B(p,n).sup.11C with the ongoing parallel reactions of .sup.11B(p,?).sup.8Be and .sup.10B(p,?).sup.7Be. The resulting radioisotopes can then be chemically separated, with one of the resulting products, namely .sup.11C, being a pure positron emitter with a half-life of 20 minutes and can be used for medical diagnostics or diagnostics of defects in materials. In another embodiment, the laser target 5 can be a layer 50 of a polymer film (CD.sub.2).sub.n capable of emitting deuterons, wherein .sup.185Re, .sup.187Re, or a natural mixture of N.sup.atRe may be used as the precursor 21 and/or 22 and/or 23 in the nuclear target 1. Natural rhenium consists of two isotopes, .sup.185Re and .sup.187Re in a ratio of 37.4: 62.6. According to this example, projectile particles 3, deuterons, are generated from the laser target 5, and if deuterons are contained in the precursor 21 and/or 22 and/or 23 in the hollow 12 of the nuclear target 1, the nuclear reactions of .sup.2H(d,n).sup.3He or .sup.2H(d,n+p).sup.2H lead to the production of neutrons and, subsequently, the reactions of .sup.185Re(n, y).sup.186Re, .sup.187Re(n,y).sup.188Re lead to the production of .sup.186Re and .sup.188Re radionuclides with half-lives of 90 and 17 hours, used in medicine like .sup.99mTc. In another example, it is possible to use the reactions .sup.3He(d,p).sup.4He, .sup.6Li(d,?).sup.4He, .sup.7Li(p,?).sup.4He, .sup.10B(p,?).sup.7Be, .sup.11B(p,2?).sup.4He, .sup.15N(p,?).sup.12C or .sup.6Li(p,.sup.3He).sup.4He followed by secondary reactions .sup.3He(.sup.6Li,2?).sup.1H and .sup.3He(.sup.3He,2p).sup.4He for the purpose of inducing an exothermic nuclear reaction. Other possible exothermic nuclear reactions include .sup.3H(d,n).sup.4He, .sup.2H(n,?).sup.3H, .sup.6Li(n.sup.3He).sup.4He, .sup.10B(n,?).sup.7Li, .sup.7Be(n,p).sup.7Li, .sup.13C(n,?).sup.14c, .sup.14N(n,p).sup.14c, .sup.17O(n,O).sup.14O .sup.21Ne(n,?).sup.18O, .sup.22Na(n,p).sup.22Ne or .sup.37Ar(n,?).sup.34S. The released energy can be converted into heat 9. FIGS. 6 and 7 schematically illustrate examples in which heat 9 is generated in a nuclear target 1. FIG. 7 schematically illustrates projectile particles 3 generated from synchrotron 301. In view of the above preferred embodiments, commonly used projectile particle accelerators 3 can be used as the generator of projectile particles 3. The projectile particle 3 induces an exothermic nuclear reaction in the nuclear target 1 upon collision with the nucleus of the precursor 21 and/or 22 and/or 23, in which heat 9 is generated in the hollow 12 of the nuclear target 1. The heat 9 is then conducted by means of a heat exchanger 91 outside the nuclear target 1. The heat exchanger 91 can subsequently be connected to a steam generator for generating electrical energy. The nuclear target 1 can be placed together with the exchanger 91 in the containment 92 according to the respective nuclear safety regulations.

[0085] In the following examples of the embodiments, the invention discloses methods for inducing nuclear reactions. In a first step, a beam of projectile particles 3 is provided.

[0086] The projectile particles 3, in a preferred embodiment, have a spectrum and intensity optimized with respect to the desired reactions. These projectile particles 3 are deposited in the hollow 12 of the nuclear target 1 containing the nuclei of the precursors 21 and/or 22 and/or 23. The projectile particles 3 either induce a nuclear 50 reaction or are elastically scattered on the isotope 4 of the material from which the nuclear target 1 is made. In a certain step of the method of the invention, after the induced reaction is burned up, the radioisotope production method ends or may be repeated; the repetition may occur in the same hollow 12 of the nuclear target 1, or the nuclear target 1 may be further moved and the projectile particles 3 are focused into a new hollow 12 containing previously unconsumed precursors 21 and/or 22 and/or 23.

[0087] One way to detect the number of nuclear reactions that have occurred on the precursor 21 and/or 22 and/or 23 is to measure the ionizing radiation emanating from the nuclear target 1. In one embodiment, nuclear reactions .sup.10B(p,?).sup.7Be can be used, thereby detecting gamma radiation from de-excitation of .sup.7Be. Monitoring of gamma radiation can then serve as an indicator of the number of induced nuclear reactions.

[0088] The accelerated projectile particles 3 can also be positive ions that can induce nuclear fusion or nuclear fission with other materials inside the hollow 12 of the nuclear target 1.

[0089] In a certain example, by combining the materials of the irradiated nuclear target 1, preferably by generating accelerated projectile particles 3 by means of the laser target 5, it is possible to induce many reactions other than those mentioned above.

[0090] Another combinations include collisions of protons, as high energy projectile particles 3 with high energy, with the nuclei of .sup.16O of the precursor 21 and/or 22 and/or 23. The collision may induce a nuclear reaction of .sup.16O(p,?).sup.13N, wherein .sup.13N is a short half-life radioisotope that may further decay by alpha decay.

[0091] In another embodiment, protons, as accelerated projectile particles 3, collide with a nuclear target 1 containing nuclei .sup.18O of the precursor 21 and/or 22 and/or 23, thereby inducing a nuclear fusion .sup.18O(p, n).sup.18F, wherein .sup.18F is a radioisotope with a half-life of 109 minutes.

[0092] In another example, protons, as accelerated projectile particles 3, collide with a nuclear target 1 containing .sup.10B, which induces a nuclear reaction of .sup.10B(p,?).sup.7Be, wherein .sup.7Be is a radioisotope with a half-life of 53 days.

[0093] In another example, protons, as accelerated projectile particles 3, collide with a nuclear target 1 containing .sup.15N, which induces a nuclear reaction of .sup.15N(p,n).sup.15O, wherein .sup.15O is a radioisotope with a short half-life.

[0094] By using other projectile particles 3, or using another laser target 5, it is possible to generate positive ion projectile particles 3. In a certain embodiment, it may be a high-energy deuteron falling into the hollow 12 of the nuclear target 1 containing the nuclei of .sup.12C of the precursor 21 and/or 22 and/or 23 which may induce a nuclear reaction of .sup.12C(d,n).sup.13N, wherein .sup.13N is a radioisotope with a short half-life.

[0095] In another example, the collision of deuterons, as accelerated projectile particles 3, with the nucleus of .sup.14N of the precursor 21 and/or 22 and/or 23 may induce a nuclear reaction of .sup.14N(d,n).sup.15O, wherein 150 is a radioisotope with a short half-life.

[0096] In another example, the collision of deuterons, as accelerated projectile particles 3, with the nucleus of .sup.20Ne of the precursor 21 and/or 22 and/or 23 may induce a nuclear reaction of .sup.20Ne(d,?).sup.18F, wherein .sup.18F is a radioisotope with a short half-life.

[0097] In other examples, a neutron can be used as the projectile particle 3, wherein it can either be accelerated by a two-stage laser target 5, where protons generated in the first laser target fall on the second laser target made of, for instance, LiF. Further, as part of the deuteron, stripping reactions are used in the reactions with the precursor 21 and/or 22 and/or 23, neutrons can be produced directly in the hollow 12, for example by means of .sup.2H(d,n).sup.3He, .sup.2H(d,n+p).sup.2H reactions and, in particular, .sup.3H(d,n).sup.4He.

[0098] In another embodiment, neutrons can also be used as projectile particles 3 for nuclear fission according to the scheme by means of the .sup.2H(d,n).sup.3He, .sup.2H(d,n+p).sup.2H reactions and, in particular, .sup.3H(d,n).sup.4He.

[0099] In another example, the nuclear target 1 can be enriched with nuclei of burnt nuclear 50 fuel or made from the material of burnt nuclear fuel, wherein a tritium precursor 23 bombarded with projectile particles 3deuteronsis placed in the hollow 12, forming a neutron pulse that fissions nuclei of heavy nuclei in .sup.233U(n,fission), .sup.235U(n,fission), .sup.239Pu(n,fission) reactions.

[0100] FIG. 9a schematically illustrates a laser-controlled laser beam emitting accelerator 55 which irradiates the laser target 5 with laser pulses 52. The laser target 5 consists of a reversed layer 51 which is exposed to the laser pulse 52, with the laser target 5 being provided with a layer 50 generating accelerated projectile particles 3 towards the hollow 12 of the nuclear target 1 by the TNSA mechanism. The accelerated projectile particles 3 pass into the hollow 12 through the opening 11, through the narrower part 121 of the hollow 12 into the wider part 122 of the hollow 12. In the hollow 12, the projectile particles 3 either collide with the nuclei of the precursor 23 or elastically scatter on isotopes 4. The narrower part 121 of the hollow 12 prevents the backscattered projectile particles 31 from leaving the hollow 12. In the example according to FIG. 9a, the nuclear target 1 is separated from the laser target 5, which is part of the laser accelerator.

[0101] In another example of the embodimentschematically illustrated according to FIG. 9b, it is possible to pre-equip the nuclear target 1 with a laser target 5, i.e. fix strongly to the nuclear target 1 so that projectile particles 3 are emitted from the laser target 5 after the laser pulse 52 strikes into the hollow 12 of the nuclear target 1. In the example according to FIG. 9b, the device is further equipped with a nuclear target 1 comprising a luminophore 8 which is deposited on the outer side 110 of the opening 11. Hence, the layer 50 emitting the projectile particles does not have to be part of the accelerator and can be supplied together with the nuclear target 1 as one product. The pre-configured laser target 5 provides the advantage of at least partially shielding the electromagnetic pulse caused by the high-power pulsed laser. This arrangement also allows the use of liquid precursors 23.

Experimental Example

[0102] An experimental setup was dedicated to behaviour of the nuclear target according to the present invention. A schematic drawings corresponding to the experimental proof are shown in FIGS. 10a and 10b.

[0103] The experimental setup, as shown in FIG. 10a, comprises a matrix of six nuclear targets made of tungsten. Each nuclear target comprises cylindrically shaped hollow with 1 mm diameter and 0.8 mm depth as shown in FIG. 10a. The total thickness of the nuclear target was 1.6 mm. The hollows were covered by MYLAR foil of thickness 23 ?m. Each hollow comprises a precursor and was filled with coumarin, which produces luminescence under UV light. Schematic drawing of the nuclear target with a matrix of hollows is shown in FIG. 10b. The following table represents the numbering of hollows as schematically shown in FIG. 10b and the laser shots performed on the respective hollow of the nuclear target. The laser pulses (30 fs) with moderate laser contrast 10.sup.?9 provided non-relativistic intensities (? 1017 W/cm.sup.2). The laser pulse energy used was either 6 or 10 Joule as indicated in the table.

TABLE-US-00001 #1 - 6 J laser shot #2 - 6 J laser shot (cavity #3 - no shot mostly missed) #4 - 10 J laser shot #5 - 10 J laser shot #6 - 10 J laser shot

[0104] In the experiment, the laser shots were directed to the hollows covered by MYLAR foil. According to the inventor's observation, the laser shots do not produce any effect of the tungsten surface of the nuclear target, irrespective of the energy of the laser pulse. It was especially evident on target #2, where laser shot missed the hollow and hit tungsten surface. The coumarin fill was not ejected from the hollow by laser shot, therefore it can be efficiently used for monitoring of nuclear reaction therein.

[0105] The powdery target material with low atomic number Z allows sufficiently long mean free path for re-scattering of both projectile and secondary particles, which leads to dissipation of beam energy within certain volume of the target. Contrary to this, high Z tungsten body of the target with large Coulomb barrier reflects the beam particles without any apparent changes of the target body at given beam parameters. The inventor further provides post-experimental analysis for each hollow, which was intended for a shot. The representative examples are shown in FIG. 11. FIG. 12 shows 50 depth analysis of the respective targets according to the lines shown in FIG. 11.

INDUSTRIAL APPLICABILITY

[0106] The present invention finds application in several industries, as, to some extent, it represents a universal method for inducing nuclear reactions. In a certain industrial application, the present invention can be used for producing radioisotopes, particularly radiopharmaceuticals. In another industrial application, the present invention can be used for transmutation of burnt nuclear fuel so that hazardous nuclear waste is converted to stable isotopes, or at least isotopes with a short half-life. In a third, but not last, industrial application, the present invention can be used to produce heat from a controlled nuclear reaction.

TABLE-US-00002 Reference Signs List 1 Nuclear target 11 Opening 110 Outer side of the opening 12 Hollow 121 First part of the hollow having a narrower cross-section 122 Second part of the hollow having an enlarged cross-section 123 Inner side of the hollow 13 Nuclear target segment 21 Precursor implanted in the material of the nuclear target around the hollow 22 Precursor forming the hollow 23 Precursor in the hollow 3 Projectile particle 31 Backscattered particles 32 Layer providing secondary projectile particles 320 Secondary projectile particles 301 Synchrotron 4 Isotope 5 Laser target 50 Layer emitting projectile particles 51 Reverse side of the layer 5 exposed to laser beam 52 Laser pulse 6 Vacuum pump 7 Shift in direction 8 Luminophore 81 Emission (macroscopic) particles direction 9 Heat 91 Heat exchanger 92 Containment