Silver river cosmic ray radiation protection method based on proton heavy ion Bragg peak

Abstract

The invention discloses a silver river cosmic ray radiation protection method based on a proton heavy ion Bragg peak. The method comprises the following steps: determining minimum energy information of ions allowed to enter a to-be-protected region; according to the ion charge, mass, energy and minimum energy information, the magnetic field intensity minimum value used for deflecting low-energy part ions with energy lower than the minimum energy information before the ions enter the to-be-protected area is given; giving the magnetic field intensity for deflecting the ions according to the minimum value of the deflection magnetic field intensity of the different types of ions; according to the magnetic field intensity, magnetic field power supply intensity is set, silver river cosmic ray protection is carried out on the to-be-protected area, and Bragg peaks of an ion dose distribution curve are prevented from being deposited in the to-be-protected area. The deposition dosage of the to-be-protected area is reduced, and effective protection of silver river cosmic rays is achieved.

Description

Technical Field

[0001] The present invention relates to a method for protecting against galactic cosmic ray radiation based on the Bragg peak of proton and heavy ion, and belongs to the technical field of radiation protection. Background Art

[0002] 1. Characteristics of the Bragg peak of proton and heavy ion

[0003] As Figure 1 shown, when protons and heavy ions enter an object, the dose distribution curve first rises gently, then rises rapidly to reach a peak (i.e., the Bragg peak), and then rapidly decreases and approaches zero. The formation of the Bragg peak of protons and heavy ions may be related to the increase in the interaction cross-section of protons and heavy ions with matter at the end of energy deposition.

[0004] The literature (Mohan R, Grosshans D. Proton therapy–present and future[J / OL]. Adv. Drug. Deliver. Rev., 2017, 109: 26-44. DOI: 10.1016 / j.addr.2016.11.006.) provides Figure 1 shows the depth dose curve of 200 MeV protons and 16 MV X-rays in water and the spread-out Bragg peak (SOBP) curve of protons. In the figure, the abscissa is the depth of irradiation in water, and the ordinate is the relative dose value. It can be seen that the dose distribution curve of 200 MeV protons shows a peak near a depth of 25 cm. In the figure, the abscissa is the depth of irradiation in water, and the ordinate is the relative dose value. It can be seen that the dose distribution curve of 200 MeV protons shows a peak near a depth of 25 cm.

[0005] The positions of the Bragg peaks of the dose deposition curves of protons and heavy ions with different energies are different. As the energy increases, the depth of the Bragg peak also increases. The literature (Lee N Y, Leeman J E, Cahlon O, et al. Target volume delineation and treatment planning for particle therapy[J]. 2018, 10.1007 / 978-3-319-42478-1(Chapter 3): 45-105. DOI: 10.1007 / 978-3-319-42478-1_3.) provides Figure 2Shows the dose distribution curves of 15 MeV and 179 MeV protons, where the main dose deposition positions in water, i.e., the positions of the Bragg peaks, are different. Based on the characteristic of the Bragg peak in the proton and heavy ion dose distribution curves, in proton and heavy ion radiotherapy, by adjusting the energy of the proton and heavy ion incident on the human body, the main dose can be accurately deposited in the human tumor target area, thereby reducing the damage to normal human cells and avoiding dose waste.

[0006] 2. Galactic Cosmic Rays and Their Protection

[0007] The Earth's own geomagnetic field and atmosphere prevent most cosmic ray charged particles from reaching the Earth's surface directly, creating a livable environment for humans. However, for most of the space in the solar system, there is no similar magnetic field and atmosphere, but it is filled with charged particles. These charged particles mainly come from solar cosmic rays and galactic cosmic rays. Solar cosmic rays are high-energy charged particle streams brought by solar storms, showing a radial shape centered on the sun, and galactic cosmic rays are high-energy charged particle streams from the Milky Way, showing an isotropic characteristic. A large number of charged particles in cosmic rays have an adverse impact on human spaceflight activities.

[0008] The patent "A Device and Method for Manipulating Charged Particles in Outer Space" (Application No.: 2024104855394, Application Date: April 22, 2024) previously applied by the applicant proposed some methods for manipulating space charged particles based on electric and magnetic fields.

[0009] The information given in Document 1 (Pal Chowdhury R, Stegeman LA, Lund ML, Fry D, Madzunkov S, Bahadori AA. Hybrid methods of radiation shielding against deep-space radiation. Life Sci Space Res (Amst). 2023 Aug; 38: 67 - 78. doi: 10.1016 / j.lssr.2023.04.004. Epub 2023 May 19. PMID: 37481310.) shows that nearly 90% of the positive ions in galactic cosmic rays are protons, 8% are helium ions, and the rest are heavier ions (atomic number Z > 2). The ion energy range in galactic cosmic rays is between 1 MeV / n and 1 TeV / n, and " / n" represents per nucleon.

[0010] Since the energy of galactic cosmic ray ions can reach up to TeV / n, the passive protection method (placing materials around the area to be protected for shielding) not only requires thick materials but also has limited shielding effect on galactic cosmic rays. It is almost impossible to shield the high-energy part of galactic cosmic rays through shielding materials, and the energy of galactic cosmic ray ions passing through the shielding materials is still continuously distributed. Inevitably, a part of the Bragg peak of the ion dose distribution curve will be deposited in the area to be protected.

[0011] Reference 2 (Moffett, Mark B., et al. "Electron particle deflection using a field reversed configuration magnetosphere geometry as an analog for radiation shielding in deep space." Advances in Space Research: The Official Journal of the Committee on Space Research (COSPAR) 9 (2022): 69.) presents a design for actively deflecting and shielding high-energy charged particles in cosmic rays by constructing a magnetic field and reducing the generation of secondary particles through collision ionization. However, currently its design can only effectively shield 11 keV electrons, and there is still a large gap in effectively shielding protons and heavy ions with typical energies of galactic cosmic rays greater than 1 GeV / n and solar protons greater than 1 MeV.

[0012] Reference 1 presents a method combining active shielding and passive protection, proposing that placing an active shielding structure (such as an electrostatic field) after using the material with the maximum shielding effect (20 g·cm -2 ) can increase the shielding effectiveness of galactic cosmic rays by up to 20%, which helps increase the number of safe days for astronauts in space (first passive shielding, then active shielding, with passive shielding as the main). Compared with simply using passive shielding protection, the hybrid protection method with an added active shielding structure plays a certain role in reducing dose deposition, but its reduction effect is limited, and thick passive shielding materials are still required.

[0013] Currently, neither the passive protection nor the active shielding method can effectively shield or deflect high-energy galactic cosmic rays. Summary of the Invention

[0014] The problem solved by the technology of the present invention is to overcome the deficiency that it is difficult to effectively protect against galactic cosmic rays by existing passive protection and active shielding methods. Based on the characteristic that the ion dose distribution curve has a Bragg peak, by avoiding the appearance of the Bragg peak of ions in the area to be protected, the deposition dose of ions in the area to be protected is reduced, thereby achieving effective protection against galactic cosmic rays.

[0015] The technical solution of the present invention is:

[0016] The present invention discloses a method for protecting against galactic cosmic ray radiation based on the Bragg peak of protons and heavy ions, including:

[0017] Determine the minimum energy information of ions allowed to enter the area to be protected;

[0018] According to the ion charge, mass, energy, and the minimum energy information, give the minimum value of the magnetic field strength for deflecting the low-energy part of ions with energy lower than the minimum energy information before the ions enter the area to be protected;

[0019] According to the minimum values of the deflection magnetic field strengths of different types of ions, give the magnetic field strength for deflecting ions;

[0020] According to the magnetic field strength, set the magnetic field power supply strength to achieve protection against galactic cosmic rays in the area to be protected and prevent the Bragg peak of the ion dose distribution curve from depositing in the area to be protected.

[0021] Further, in the above method, the determination of the minimum energy information of ions allowed to enter the area to be protected is specifically:

[0022] Combined with the information of the material, thickness, and ion type of the area to be protected, respectively give the minimum energy information for each type of ion to penetrate the area to be protected and deposit the Bragg peak outside the area to be protected.

[0023] Further, in the above method, the minimum value of the magnetic field strength is specifically:

[0024] B = βE1 / (qcr)

[0025] Wherein, B is the minimum value of the magnetic field strength, β is the relativistic velocity factor, c is the speed of light, r is the deflection radius, E1 is the minimum energy information; q is the ion charge.

[0026] Further, in the above method, according to the minimum values of the deflection magnetic field strengths of different types of ions, giving the magnetic field strength for deflecting ions is specifically: take the maximum value among the minimum values of the magnetic field strengths of different types of ions as the magnetic field strength to be finally set.

[0027] Further, in the above method, the deflection radius is the distance between the position where the ions enter the deflection magnetic field and the area to be protected.

[0028] Further, in the above method, the area to be protected is a component, a spacecraft, a human body or a microorganism.

[0029] Further, in the above method, the area to be protected can be in space or on the surface of a planet.

[0030] Further, in the above method, the ions are galactic cosmic rays or ions with a Bragg peak; the magnetic field is a superconducting magnetic field or a normal electromagnetic field.

[0031] The beneficial effects of the present invention compared with the prior art are as follows:

[0032] (1) The present invention effectively protects against galactic cosmic rays, avoiding the need for thick shielding materials for passive shielding to achieve effective protection, and also avoiding the need for extremely strong magnetic fields for active shielding to achieve effective protection. Instead, it provides a feasible method to deflect low-energy ions with a lower-intensity magnetic field, allowing high-energy ions to directly enter the area to be protected, and making the position of the Bragg peak of the dose distribution curve of the ions entering the area to be protected appear outside the area to be protected, with the position of the area to be protected corresponding to the smooth section of the ion dose distribution curve, thereby reducing the dose deposition of galactic cosmic ray ions in the area to be protected.

[0033] (2) The present invention makes full use of the characteristic that the proton heavy ion dose distribution curve has a Bragg peak, and by avoiding the appearance of the Bragg peak of ions in the area to be protected, the deposited dose of ions in the area to be protected is reduced, avoiding large-dose-rate irradiation of devices and organisms in space exploration activities.

[0034] (3) The present invention makes full use of the characteristic that when a magnetic field deflects ions, it does not change the ion energy but only changes the ion transmission direction. While deflecting low-energy ions away from the area to be protected, the energy of high-energy ions remains unchanged, thereby avoiding the situation where the energy of all ions is reduced during passive shielding, avoiding the position of the Bragg peak of the ion dose distribution curve appearing in the area to be protected, and reducing the deposited dose of ions in the area to be protected.

[0035] (4) In the present invention, only low-energy ions need to be deflected away from the area to be protected, and high-energy ions still pass through the area to be protected, avoiding the situation where the magnetic field intensity required to deflect all ions away from the area to be protected is too large during active shielding, or the electric field intensity required to reduce the ion energy to 0 is too large, and it is difficult for related active shielding devices to completely deflect galactic cosmic rays away from the area to be protected.

[0036] (5) The core point of the present invention is to avoid the appearance of the Bragg peak in the ion dose distribution within the area to be protected, which is applicable to all ions with Bragg peak characteristics in the dose distribution curve, not just the ions of galactic cosmic rays. The method is to deflect low-energy ions with a magnetic field so that they do not enter the area to be protected, thereby avoiding the position of the Bragg peak in the low-energy ion dose distribution from appearing in the area to be protected and reducing the deposition dose of ions in the area to be protected. The present invention is of great significance for radiation protection of aerospace devices, human radiation protection, and radiation protection of microorganisms in the in-situ manufacturing of microorganisms in the space environment, providing safety guarantees for human deep space exploration, manned lunar landing and other space exploration activities.

[0037] (6) The present invention proposes to deflect the low-energy part of the ions in galactic cosmic rays, and the high-energy part of the ions directly penetrate the area to be protected (before the ions enter the area to be protected, the low-energy part of the ions can be actively deflected first, without the need for passive shielding, or the ions can be first energy-reduced with passive shielding and then actively shielded to reduce the intensity requirement of the deflection magnet for active shielding). By utilizing the characteristic that the proton and heavy ion dose distribution curve has a Bragg peak, the Bragg peak of the dose distribution curve is deposited outside the area to be protected, thereby reducing the deposition dose in the area to be protected, and realizing effective protection against galactic cosmic rays. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the depth dose curve of protons and X-rays in water and the proton extended Bragg peak curve;

[0039] Figure 2 is the dose distribution curve of protons and carbon ions in water;

[0040] Figure 3 is the schematic diagram of the galactic cosmic ray radiation protection based on the Bragg peak of proton and heavy ion of the present invention;

[0041] Figure 4 is the flow chart of the galactic cosmic ray radiation protection method based on the Bragg peak of proton and heavy ion of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following further elaborates on the present invention patent in detail in conjunction with the drawings and specific embodiments.

[0043] As Figure 4 shown, the present invention discloses a galactic cosmic ray radiation protection method based on the Bragg peak of proton and heavy ion, including:

[0044] Determine the minimum energy information of the ions allowed to enter the area to be protected;

[0045] According to the ion charge, mass, energy, and the lowest energy information, the minimum value of the magnetic field strength is given for deflecting the low-energy part of the ions with energy lower than the lowest energy information before the ions enter the area to be protected.

[0046] According to the minimum value of the deflection magnetic field strength for different types of ions, the magnetic field strength for deflecting the ions is given.

[0047] According to the magnetic field strength, the magnetic field power supply strength is set to achieve the protection against galactic cosmic rays for the area to be protected and prevent the Bragg peak of the ion dose distribution curve from depositing in the area to be protected.

[0048] Preferably, the lowest energy information of the ions allowed to enter the area to be protected is determined, specifically:

[0049] Combined with the information of the material, thickness, and ion type of the area to be protected, the lowest energy information for each type of ion to penetrate the area to be protected and deposit the Bragg peak outside the area to be protected is given respectively.

[0050] Preferably, the minimum value of the magnetic field strength is specifically:

[0051] B = βE1 / (qcr)

[0052] Wherein, B is the minimum value of the magnetic field strength, β is the relativistic velocity factor, c is the speed of light, r is the deflection radius, E1 is the lowest energy information; q is the ion charge.

[0053] Preferably, according to the minimum value of the deflection magnetic field strength for different types of ions, the magnetic field strength for deflecting the ions is given, specifically: taking the maximum value among the minimum values of the magnetic field strengths of different types of ions as the magnetic field strength to be finally set.

[0054] Preferably, the deflection radius is the distance between the position where the ions enter the deflection magnetic field and the area to be protected.

[0055] Preferably, the area to be protected is components, spacecraft, human body or microorganisms.

[0056] Preferably, the area to be protected can be in space or on the surface of a planet.

[0057] Preferably, the ions are galactic cosmic rays or ions with Bragg peaks; the magnetic field is a superconducting magnetic field or a common electromagnetic field.

[0058] Preferably, the ions are decelerated by a passive shielding material or an electric field before entering the magnetic field.

[0059] Embodiment

[0060] Such as Figure 2In this case, if the material in the area to be protected is close to water (biological materials can generally be approximated as water), and the depth range is within 5 cm, the dose distribution curve of 179 MeV protons is a smooth section within this range, and the position of the Bragg peak with a large amount of dose deposition is outside the area to be protected. While the main dose deposition position of the 15 MeV proton dose distribution curve covers a depth within 5 cm, and a magnetic field is required to deflect it away from the protected area.

[0061] As Figure 3 shown, a magnetic field is set around the area to be protected. The figure shows a schematic diagram of charged ions in galactic cosmic rays irradiating from a certain direction. The magnetic field outside the protected area deflects the low-energy part of the ions in galactic cosmic rays away from the protected area, and the high-energy part of the ions passes through the protected area, depositing a small amount of dose, without leaving the main dose distribution position (Bragg peak) within the protected area.

[0062] As Figure 4 shown, this embodiment provides a method for protecting against galactic cosmic ray radiation based on the Bragg peak of protons and heavy ions, including the following steps:

[0063] (1) Combining information such as the material, thickness, and ion type of the area to be protected, the minimum energy E1 at which ions penetrate the protected area and deposit the Bragg peak outside the protected area is given. If multiple ions are involved, the corresponding minimum energies need to be given separately. The Bragg peak deposition position of ions in the corresponding material can be obtained by querying relevant databases (such as the NIST corresponding database pstar, etc.) or through experiments to obtain relevant data.

[0064] (2) According to information such as the ion charge q, mass m, energy E, etc., and the minimum energy E1 information calculated in the previous step (1), the strength B of the magnet for deflecting the low-energy part of the ions with energy lower than E1 before the ions enter the protected area is given.

[0065] The deflection radius r of the magnetic field for ions is r = βE / (Bqc), where β is the relativistic velocity factor and c is the speed of light. According to the position where the ions enter the deflection magnetic field and the direction of ion advancement, the deflection radius r is determined as the distance between the position where the ions enter the deflection magnetic field and the protected area. Then the minimum value of the magnet strength required for the corresponding ions is B 1 = β 1 E 1 / (q 1 cr), and ions of this type with energy lower than E 1 will all be deflected away from the protected area by the action of the B 1 magnetic field; a passive shielding material layer can also be set before the ions reach the deflection magnet to first reduce the energy of the ions, thereby reducing the strength requirement of the deflection magnet. Take the maximum value B of the minimum deflection magnetic field strengths B 1 of different ions as the final magnetic field strength.

[0066] (3) The control module issues an instruction to the magnet power supply. In the control module, the deflection magnet intensity around the area to be protected is set to B. The control module converts the corresponding instruction into the magnet power supply intensity I, adjusts the magnet power supply to change the magnetic field intensity, so as to achieve the protection of the area to be protected against galactic cosmic rays and prevent the Bragg peak deposition of the ion dose distribution curve in the area to be protected.

[0067] This embodiment relates to a radiation protection method for galactic cosmic rays (GCR). In view of the fact that the energy of galactic cosmic ray particles is high and both passive shielding and active shielding are ineffective in protecting against high-energy galactic cosmic rays, a magnetic field is used to deflect the low-energy part of the particles in galactic cosmic rays, allowing the high-energy part of the particles to directly pass through the object to be protected. Due to the Bragg peak characteristics of the proton heavy ion dose deposition curve, the dose deposited in the area to be protected is greatly reduced, and finally the area to be protected is protected. It is of great significance for the radiation protection of aerospace devices, human radiation protection, and radiation protection of microorganisms in the in-situ manufacturing scenario of microorganisms in the space environment.

[0068] By placing a magnetic field to deflect the low-energy part of the ions in galactic cosmic rays, making them away from the area to be protected and allowing the higher-energy ions to pass through the area to be protected. Due to the Bragg peak characteristics of the proton heavy ion dose deposition curve, the dose finally deposited in the area to be protected is greatly reduced.

[0069] The energy dividing line between the low-energy part and the higher-energy part is related to the thickness, material, ion type, etc. of the area to be protected. The low-energy part of the ions mainly refers to the ions that may deposit the dose corresponding to the Bragg peak (the main dose deposition area) in the area to be protected when passing through the area to be protected. The higher-energy ions correspond to the ions that will not deposit the dose corresponding to the Bragg peak in the area to be protected when passing through the area to be protected.

[0070] Since the magnetic field does not change the ion energy, placing a magnetic field to deflect the low-energy part of the ions can cause a break in the ion energy distribution finally passing through the area to be protected, avoiding the situation that due to the continuity of the energy distribution in passive shielding, there is always the Bragg peak deposition of ions in the area to be protected.

[0071] When placing a device that generates a magnetic field around the area to be protected, it is necessary to deflect the low-energy part of the proton heavy ions in galactic cosmic rays in all directions and reduce the generation of secondary particles to avoid the harm of secondary particles.

[0072] The area to be protected can be components, spacecraft, human body, microorganisms, etc.

[0073] The area to be protected can be in space or on the surface of a planet.

[0074] In this embodiment, such asFigure 3 As shown, a magnetic field is set around the area to be protected. The figure shows a schematic diagram of charged ions in galactic cosmic rays irradiating from a certain direction. The magnetic field outside the area to be protected deflects the ions with low energy in the galactic cosmic rays away from the area to be protected. The ions with high energy pass through the area to be protected and deposit a small amount of dose, without leaving the main dose distribution position (Bragg peak) in the area to be protected.

[0075] The magnetic field intensity is adjusted according to the material and thickness of the area to be protected, as long as the high-energy ions entering the area to be protected do not deposit the Bragg peak in this area. Thus, it plays a role in radiation protection by reducing the dose deposition in the area to be protected.

[0076] It is also possible to place shielding materials outside the magnetic field to first reduce the energy of the charged ions in the galactic cosmic rays, thereby reducing the requirements for the magnetic field intensity.

[0077] For the shielding of galactic cosmic rays, the magnetic field deflects the ions with low energy, allowing the ions with high energy to directly irradiate the area to be protected but not deposit the Bragg peak in the area to be protected, thereby reducing the dose deposition in the protected area.

[0078] Before the low-energy ions are deflected, it is also possible to place shielding materials to reduce the energy of the ions, thereby reducing the requirements for the intensity of the deflection magnetic field.

[0079] Deflecting the ions with a magnetic field does not change the ion energy, thus causing a gap in the ion energy spectrum of the ions finally entering the area to be protected, and finally no Bragg peak will be deposited in the area to be protected. Reducing the dose deposition in the area to be protected plays a role in radiation protection.

[0080] The method for radiation protection of galactic cosmic rays based on the Bragg peak of protons and heavy ions disclosed in this embodiment sets a magnetic field around the area to be protected for actively deflecting ions. The magnetic field deflects the low-energy ions, and the high-energy ions that cannot be deflected by the magnetic field can enter the area to be protected, while the main dose deposition area (at the Bragg peak) of its dose distribution curve does not appear in the protected area. This method is applicable to the radiation protection of all ions with dose distribution curves having the characteristics of Bragg peaks, not only the ions in galactic cosmic rays.

[0081] Although the content of the present invention has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

[0082] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak, characterized in that: include: Determine the minimum energy information of ions allowed to enter the area to be protected; According to the ion charge, mass and energy and the minimum energy information, the minimum value of the magnetic field intensity used to deflect the low-energy ions whose energy is lower than the minimum energy information before the ions enter the area to be protected is given; According to the minimum value of the deflection magnetic field strength of different types of ions, the magnetic field strength used to deflect ions is given; According to the magnetic field strength, the magnetic field power supply strength is set to realize galactic cosmic ray protection for the protected area and prevent the Bragg peak of the ion dose distribution curve from being deposited in the protected area.

2. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 1, characterized in that: The minimum energy information of the ions allowed to enter the protected area is determined as follows: Combined with the material, thickness, and ion type information of the area to be protected, the minimum energy information for each ion to penetrate the area to be protected and deposit the Bragg peak outside the area to be protected is given.

3. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 1, characterized in that: The minimum value of the magnetic field strength is specifically: B=βE1 / (qcr) Among them, B is the minimum magnetic field strength, β is the relativistic speed factor, c is the speed of light, r is the deflection radius, E1 is the minimum energy information, and q is the ion charge.

4. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 3, characterized in that: According to the minimum value of the deflection magnetic field strength of different types of ions, the magnetic field strength used to deflect the ions is given, specifically: the maximum value among the minimum values ​​of the magnetic field strength of different types of ions is taken as the final magnetic field strength to be set.

5. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 3, characterized in that: The deflection radius is the distance between the position where the ions enter the deflection magnetic field and the area to be protected.

6. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 1, characterized in that: The area to be protected is a component, a spacecraft, a human body or a microorganism.

7. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 1, characterized in that: The area to be protected may be in space or on the surface of a planet.

8. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 1, characterized in that: The ions are galactic cosmic rays or ions with Bragg peaks; and the magnetic field is a superconducting magnetic field or a common electromagnetic field.

9. The galactic cosmic ray radiation protection method based on the proton and heavy ion Bragg peak according to claim 1, characterized in that: The ions are de-energized by passive shielding materials or electric fields before entering the magnetic field.

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