JP2017209634A - Selective excitation method of isotope and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively excite an isotope of an odd-numbered mass number among a plurality of kinds of isotopes of the same atom, without using a laser beam of circular polarization.SOLUTION: First and second linear polarization laser beams are generated. The first and second linear polarization laser beams are irradiated to an object substance 1 including an isotope of an odd-numbered mass number and an even-numbered mass number. The polarization direction of the first linear polarization laser beam is orthogonal to the polarization direction of the second linear polarization laser beam in a position of the object substance 1. A wavelength of the first and second linear polarization laser beams is set in a wavelength for selectively exciting the isotope of the odd-numbered mass number in two stages among the isotope of the odd-numbered mass number and the even-numbered mass number by the first and second linear polarization laser beams.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and apparatus for selectively exciting an isotope having an odd mass number among a plurality of types of isotopes of the same atom.

The same atom has an isotope having an odd mass number (hereinafter simply referred to as an odd mass number) and an isotope having an even mass number (hereinafter simply referred to as an even mass number).
By selectively exciting an isotope having an odd mass number among the plurality of types of isotopes with respect to the same atom, the isotopes having an odd mass number can be separated from the isotopes having an even mass number. Such a technique is described in Patent Document 1 and Non-Patent Document 1, for example.

  In Patent Document 1 and Non-Patent Document 1, circularly polarized first and second laser beams are irradiated to a target substance containing a plurality of types of isotopes of the same atom. This selectively excites odd mass isotopes in only two stages. Furthermore, by irradiating the target substance with a third laser beam, the isotopes having an odd mass number selectively excited are ionized. At this time, the ionized isotope is separated from the isotopes having an even mass number by applying an electric field or a magnetic field.

If the multiple types of isotopes are radioactive wastes containing, for example, palladium isotopes having mass numbers of 102, 104, 105, 106, 107, 108, and 110 (hereinafter referred to as Pd isotopes), In Literature 1 and Non-Patent Literature 1, radioactive ¹⁰⁷ Pd can be extracted to reduce the radiation dose as follows.

Radioactive waste is collected on the filter as an insoluble residue in the reprocessing step. By irradiating the vapor of the insoluble residue with a circularly polarized first laser beam having a wavelength of 276 nm and a circularly polarized second laser beam having a wavelength of 521 nm, an odd mass number of ¹⁰⁷ Pd and ¹⁰⁵ Pd Is selectively excited in two stages. At the same time, ¹⁰⁷ Pd and ¹⁰⁵ Pd are further excited by irradiating the vapor of the insoluble residue with the third laser beam. Thereby, ¹⁰⁷ Pd and ¹⁰⁵ Pd are ionized. The ionized ¹⁰⁷ Pd and ¹⁰⁵ Pd are separated from the undissolved residue (even mass number Pd isotopes) by application of an electric or magnetic field.

Japanese Patent Publication No.7-16584

"Plasma laser isotope separation test report", report number PNC-TN8410 95-077, April 1995, Tokai Works, Power Reactor and Nuclear Fuel Development Corporation

In Patent Document 1 and Non-Patent Document 1, circularly polarized first and second laser beams are used to selectively excite odd mass isotopes among a plurality of types of isotopes of the same atom in two stages. Used.
In order to generate circularly polarized laser light, an optical element (for example, a quarter wavelength plate) that converts the laser light into circularly polarized light after generating linearly polarized laser light is required.
In addition, when a mirror is used to guide circularly polarized laser light to a target substance (for example, the above-described insoluble residue vapor), the accuracy of circularly polarized light is reduced as follows. When circularly polarized laser light is reflected by the incident plane of the mirror, the electric field component of the laser light perpendicular to the incident plane and the electric field component of the laser light parallel to the incident plane have different reflectivities at the incident plane. As a result, the reflected laser light shifts from circularly polarized light to elliptically polarized light. The greater this deviation, the more even-numbered mass isotopes are included in the isotopes that are excited in two stages.

  Therefore, an object of the present invention is to provide a method and apparatus that can selectively excite an isotope having an odd mass number among a plurality of types of isotopes of the same atom without using circularly polarized laser light.

In order to achieve the above object, according to the present invention, there is provided an isotope selective excitation method for selectively exciting an odd-numbered isotope among odd-numbered and even-numbered isotopes of the same atom,
(A) generating first and second linearly polarized laser beams;
(B) irradiating the target substance containing isotopes of odd and even mass numbers with the first and second linearly polarized laser beams,
In (B), at the position of the target substance, the polarization direction of the first linearly polarized laser beam is orthogonal to the polarization direction of the second linearly polarized laser beam,
The wavelengths of the first and second linearly polarized laser beams are selected from two odd-numbered and even-numbered isotopes by using the first and second linearly polarized laser beams. An isotope selective excitation method is provided that is set to the wavelength to be excited.

In order to achieve the above object, according to the present invention, there is provided an isotope selective excitation apparatus that selectively excites an odd-numbered isotope among odd-numbered and even-numbered isotopes of the same atom. And
A first laser irradiation apparatus for generating a first linearly polarized laser beam and irradiating the target substance containing isotopes of odd and even mass numbers with the first linearly polarized laser beam;
A second laser irradiation device that generates a second linearly polarized laser beam and irradiates the target material with the second linearly polarized laser beam,
The first laser irradiation device and the second laser irradiation device are configured so that the polarization direction of the first linearly polarized laser beam is orthogonal to the polarization direction of the second linearly polarized laser beam at the position of the target substance. ,
The wavelengths of the first and second linearly polarized laser beams are selected from two odd-numbered and even-numbered isotopes by using the first and second linearly polarized laser beams. An isotope selective excitation device is provided that is set to the wavelength to be excited.

  In one example, the isotope is an isotope of a palladium atom, and the wavelengths of the first and second linearly polarized laser beams are 276 nm and 521 nm, respectively.

The present invention has been made on the basis of a new finding that an isotope having an odd number of masses can be selectively excited in two stages even by two linearly polarized lights whose polarization directions are orthogonal to each other. That is, by irradiating a plurality of isotopes of the same atom with two linearly polarized lights whose polarization directions are orthogonal to each other, an isotope having an odd mass number is selectively given a quantum number m _F of its total angular momentum. It can be excited in two stages from the ground state so as to change by a number.

Based on this knowledge, according to the present invention, the first and second linearly polarized laser beams whose polarization directions are orthogonal to each other are irradiated to the target substance containing isotopes of odd and even mass numbers. This selectively excites odd-numbered isotopes in two stages.
Therefore, it is possible to selectively excite an isotope having an odd mass number among isotopes having an odd mass number and an even mass number without using a circularly polarized laser beam.

1 shows a configuration of an isotope selective excitation apparatus according to an embodiment of the present invention. It is explanatory drawing of the energy level of Pd isotope of an even-numbered mass number. It is explanatory drawing of the energy level of Pd isotope of odd-number mass number. It is explanatory drawing in the case of exciting the Pd isotope of odd mass number with two circularly polarized laser beams. A configuration example in the case where a reflection optical system is provided is shown.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 shows a configuration of an isotope selective excitation apparatus 10 according to an embodiment of the present invention. The selective excitation device 10 is a device that selectively excites an isotope having an odd mass number among a plurality of types of isotopes of the same atom. In the present embodiment, the plurality of types of isotopes are palladium atom isotopes (hereinafter referred to as Pd isotopes). As a plurality of types of Pd isotopes, there are palladium isotopes ¹⁰² Pd, ¹⁰⁴ Pd, ¹⁰⁵ Pd, ¹⁰⁶ Pd, ¹⁰⁷ Pd, ¹⁰⁸ Pd, and ¹¹⁰ Pd.

  In FIG. 1, the selective excitation device 10 irradiates the target substance 1 including the odd-numbered and even-numbered Pd isotopes with the first and second linearly polarized laser beams, thereby causing the odd-numbered Pd isotopes. The body is selectively excited in two stages. The target substance 1 may be a gas as shown in FIG. In FIG. 1, the target substance 1 is a substance containing a plurality of types of Pd isotopes (for example, the above-described insoluble residue of radioactive waste) converted into vapor by an electron gun, a heating device, or the like. For example, the crucible 2 is arranged in a vacuum chamber, the object is put in the crucible 2 and an electron beam is applied to the object. Thereby, the vapor | steam of this object is generated as the target substance 1.

  In the present embodiment, the selective excitation device 10 is provided in the ionization device 20. The ionizer 20 ionizes the odd mass Pd isotopes selectively excited in two stages by the selective excitation device 10. The configuration of the ionizer 20 will be described later.

(Configuration of selective excitation device)
The selective excitation device 10 includes a first laser irradiation device 3 and a second laser irradiation device 5.
The first laser irradiation device 3 generates a first linearly polarized laser beam, and irradiates the target material 1 containing Pd isotopes having odd and even mass numbers with the first linearly polarized laser beam.
The second laser irradiation device 5 generates a second linearly polarized laser beam and irradiates the target substance 1.
The first laser irradiation device 3 and the second laser irradiation device 5 are configured so that the polarization direction of the first linearly polarized laser beam is orthogonal to the polarization direction of the second linearly polarized laser beam at the position of the target substance 1. ing. The polarization direction is the vibration direction of the electric field.

  The wavelengths of the first and second linearly polarized laser beams are selected from the ground state by selecting the odd-numbered and even-numbered Pd isotopes from the ground state by using the first and second linearly polarized laser beams. Therefore, the wavelength is set to be excited in two stages. Specifically, the wavelength of the first linearly polarized laser beam is 276 nm (preferably strict value is 276.3 nm), and the wavelength of the second linearly polarized laser beam is 521 nm (preferably strict value is 521.0 nm). It is.

Note that the first linearly polarized laser beam may have a substantial intensity within a wavelength range of 276.25 nm or more and 276.34 nm or less. For example, outside this range, the intensity of the first linearly polarized laser beam may be zero at any wavelength.
Similarly, the second linearly polarized laser beam may have a substantial intensity within a wavelength range of 520.95 nm or more and 521.04 nm or less. For example, outside this range, the intensity of the second linearly polarized laser light may be zero at any wavelength.

  In the present embodiment, the first laser irradiation device 3 includes a laser emitting unit 7, a plurality of mirrors 9 a and 9 b, a polarizing element 11, and a polarization direction adjusting element 13.

The laser emitting unit 7 emits linearly polarized laser light having a wavelength of 276 nm (that is, first linearly polarized laser light). The laser emitting unit 7 is, for example, a dye laser.
Each of the plurality of mirrors 9 a and 9 b reflects the laser light from the laser emitting unit 7 to guide the laser light to the target substance 1.

  The polarizing element 11 improves the degree of linear polarization of the first linearly polarized laser beam emitted from the laser emitting unit 7. The polarizing element 11 may be a polarizing prism, for example. When the laser emitting unit 7 emits laser light that is not linearly polarized light, the polarization element 11 converts the laser light emitted from the laser emitting unit 7 into linearly polarized light (that is, first linearly polarized laser light). . When the laser emitting unit 7 emits the first linearly polarized laser beam, the polarizing element 11 may be omitted in FIG.

  The polarization direction adjustment element 13 changes the polarization direction of the first linearly polarized laser beam that has passed through the polarization element 11. Thereby, the polarization direction of the first linearly polarized laser beam that has passed through the polarization direction adjusting element 13 and the polarization direction of the second linearly polarized laser beam generated by the second laser irradiation device 5 are the positions of the target substance 1. Are orthogonal to each other. The polarization direction adjusting element 13 may be a half-wave plate, for example.

  In the present embodiment, the second laser irradiation device 5 includes a laser emitting unit 15, a plurality of mirrors 17 a and 17 b, and a polarizing element 19.

The laser emitting unit 15 emits linearly polarized laser light having a wavelength of 521 nm (that is, second linearly polarized laser light). The laser emitting unit 15 is, for example, a dye laser.
Each of the plurality of mirrors 17 a and 17 b reflects the laser beam from the laser emitting unit 15 to guide the laser beam to the target substance 1.

  The polarizing element 19 improves the degree of linear polarization of the second linearly polarized laser beam emitted from the laser emitting unit 15. The polarizing element 19 may be a polarizing prism, for example. When the laser emitting unit 15 emits laser light that is not linearly polarized light, the polarization element 19 converts the laser light emitted from the laser emitting unit 15 into linearly polarized light (that is, second linearly polarized laser light). . When the laser emitting unit 15 emits the second linearly polarized laser beam, the polarizing element 19 may be omitted in FIG.

  The first laser irradiation device 3 and the second laser irradiation device 5 are configured so that the first and second linearly polarized laser beams are irradiated to the same position in the target material 1. Therefore, in the example of FIG. 1, the first linearly polarized laser beam and the second linearly polarized laser beam travel on the same imaginary straight line that penetrates the target substance 1 by the plurality of mirrors 9a, 9b, 17a, and 17b. The light travels in opposite directions and enters the target substance 1.

In a preferred example, the first and second linearly polarized laser beams have a cross-sectional area of 3 cm ² or more (more preferably 6 cm ² or more) at a position where they enter the target substance 1. Here, the cross-sectional area of the linearly polarized laser light is an area of a cross section by a plane orthogonal to the traveling direction of the laser light. For example, the cross sections of the first and second linearly polarized laser beams are circular with a radius of about 2 cm. Thus, by increasing the cross-sectional area of the linearly polarized laser beam, the first and second linearly polarized laser beams can be irradiated to Pd isotopes having many odd mass numbers.

In the selective isotope selective excitation method of the present embodiment using the selective excitation device 10 having the above-described configuration, the first and second linearly polarized laser beams are generated and irradiated on the target substance 1, thereby Of the odd-numbered and even-numbered Pd isotopes in the substance 1, the odd-numbered Pd isotopes are selectively excited in two stages.
The odd mass Pd isotopes thus excited in two stages are ionized and collected by the ionizer 20.

  The ionization device 20 includes a third laser irradiation device 21 and a collection device 27 in addition to the selective excitation device 10.

  The third laser irradiation device 21 irradiates the target material 1 with the third laser light at the same time that the target material 1 is irradiated with the first and second linearly polarized laser beams. The third laser light excites an odd mass Pd isotope excited in two stages by the first and second linearly polarized laser lights to a Rydberg level having a main quantum number n of 9 or more. Thereby, the odd mass Pd isotopes are automatically ionized. In order to excite the Pd isotope in this way, the wavelength of the third laser beam is, for example, 801.8 nm, 760.1 nm, 760.6 nm, 730.9 nm, 712.0 nm, or 699.1 nm. Good.

  In the example of FIG. 1, the third laser irradiation device 21 includes a laser emitting portion 23 that emits third laser light and a mirror 25. The third laser light from the laser emitting unit 23 is reflected by the mirror 25 and enters the mirror 17b. The mirror 25 is a dichroic mirror that reflects light of a specific wavelength and transmits light of other wavelengths. That is, the dichroic mirror 25 transmits the laser light from the laser emitting unit 15 and reflects the third laser light from the laser emitting unit 23. As a result, the laser beam from the laser emitting unit 15 and the third laser beam overlap so as to propagate through the same path, and are reflected by the mirror 17b and enter the target substance 1.

  The collection device 27 collects the ionized Pd isotope at a desired location. The collection device 27 includes, for example, a metal electrode 28, a wire mesh electrode 29, and a collection substrate 31. By applying a positive voltage to the metal electrode 28 and grounding the wire mesh electrode 29, the ionized Pd isotope passes through the wire mesh electrode 29 and is deposited on the collection substrate 31.

  In the following, the structure of energy levels of a plurality of types of Pd isotopes and selective excitation based on this structure will be described.

(Energy level structure)
FIG. 2 is an explanatory diagram of energy levels of Pd isotopes having an even mass number. The nuclear spin I of Pd isotopes with even mass numbers is zero. In the ground state (total angular momentum J = 0), the z component m _J of _J is zero. In the first excited state (J = 1), the z component m _J of _J takes a value of zero and ± 1. In the second excited state (J = 0), the z component m _J of _J is zero.

FIG. 3 is an explanatory diagram of energy levels of Pd isotopes having odd mass numbers. The energy levels of the odd mass Pd isotopes have a complex structure as shown in FIG. This is because the nuclear spin I of the odd mass Pd isotope is not 0, and the total angular momentum F (= J + I) is split into many m _F levels.

The value of the total angular momentum F that can be taken in the ground state (J = 0) by the odd-numbered Pd isotope is 5/2. The z component m _F of _F can take (2F + 1) types of values. Specifically, the z component m _F of F = 5/2 takes six values of −5/2, −3/2, −1/2, 1/2, 3/2, and 5/2. be able to.

There are three types of total angular momentum F that can be taken by the odd mass Pd isotope in the first excited state (J = 1): 3/2, 5/2, and 7/2. In each of these total angular momentums F, the z component m _F of _F can take (2F + 1) types of values. Specifically, the z component m _F of F = 3/2 can take four values of −3/2, −1/2, 1/2, 3/2, and F = 5 / The z component m _F of 2 can take six values of −5/2, −3/2, −1/2, 1/2, 3/2, and 5/2, and F = 7/2. the z-component _{m F, -7 / 2, -5} / 2, -3 / 2, taking the eight values of -1 / 2,1 / 2,3 / 2,5 / 2,7 / 2 Can do.

The value of the total angular momentum F that an odd mass Pd isotope can take in the second excited state (J = 0) is 5/2. The z component m _F of _F can take (2F + 1) types of values. Specifically, the z component m _F of F = 5/2 takes six values of −5/2, −3/2, −1/2, 1/2, 3/2, and 5/2. be able to.

(Selective excitation)
As shown in FIG. 2, the Pd isotope having an even mass number in the ground state is excited to the first excited state when it absorbs the first linearly polarized laser beam having the wavelength λ ₁ = 276 nm. Since this excitation is performed by linearly polarized light, the z component m _F of the total angular momentum F of the Pd isotope is not changed by this excitation (Δm _F = 0).

When the Pd isotopes having an even number of masses are irradiated with the first and second linearly polarized laser beams whose polarization directions are orthogonal to each other, the first excited state of m _J = 0 by absorbing the first linearly polarized laser beam The even mass number Pd isotope that has transitioned to cannot absorb the second linearly polarized laser beam. This is because there is no level (−1, +1) that satisfies Δm _J = ± 1 in the second excited state. Therefore, the Pd isotope having an even mass number is not excited to the second excited state.

  On the other hand, the odd mass Pd isotopes are excited to the second excited state as follows.

First, as shown in FIG. 3, the odd-number Pd isotope is excited to the first excited state when it absorbs the first linearly polarized laser beam having the wavelength λ ₁ = 276 nm. Since this excitation is performed by linearly polarized light, the z component m _F of the total angular momentum F of the Pd isotope is not changed by this excitation (Δm _F = 0).

The odd-number-mass Pd isotope thus excited in the first excited state is excited in the second excited state as shown in FIG. 3 when absorbing the second linearly polarized laser beam having the wavelength λ ₂ = 521 nm. . In the second excited state, the odd mass Pd isotope is different from the even mass Pd isotope, and the z component m _F of the total angular momentum F can take various values as shown in FIG. it can. Therefore, the odd mass Pd isotope absorbs both the first and second linearly polarized laser beams whose polarization directions are orthogonal to each other, so that the z component m _F of the total angular momentum F changes by ± 1. To the second excited state (Δm _F = ± 1).

(Operational effect of this embodiment)
According to this embodiment, the following effects can be obtained.

  As described above, according to the present embodiment, the Pd isotope having an odd mass number is selected as described above by simultaneously irradiating the target material 1 with the first and second linearly polarized laser beams whose polarization directions are orthogonal to each other. Thus, it is excited to the second excited state.

  In addition, since it is not necessary to use circularly polarized light to selectively excite odd mass Pd isotopes to the second excited state, an optical element (for example, a quarter-wave plate) for generating circularly polarized light is unnecessary. become.

  Furthermore, in this embodiment, since the polarization degree of linearly polarized light can be easily increased, the target material 1 can be irradiated with the first and second linearly polarized laser beams having a high degree of polarization. Thereby, it is possible to selectively excite odd-numbered Pd isotopes to the second excited state at a higher rate than when circularly polarized light whose polarization degree is difficult to increase is used. Details are as follows.

  Consider a case where an odd mass Pd isotope is excited to a second excited state by two circularly polarized laser beams as in Patent Document 1. In this case, since circularly polarized light tends to become elliptically polarized light due to reflection by the mirror, it is difficult to irradiate the target substance 1 with completely circularly polarized laser light. If the circularly polarized laser beam is elliptically polarized light deviated from perfect circularly polarized light, the Pd isotope having an even mass number is also excited to the second excited state. The number of Pd isotopes having an even mass number increases as the shift from circularly polarized light to elliptically polarized light increases, and the number of Pd isotopes having an odd mass number excited to the second excited state correspondingly decreases. According to Non-Patent Document 1, the ratio of the odd mass Pd isotopes occupied in the Pd isotopes excited and ionized in the second excited state is 74%.

  On the other hand, it is easy to generate linearly polarized light with a high degree of polarization. Therefore, in the present embodiment, the target substance 1 can be easily irradiated with the first and second linearly polarized laser beams having a high degree of polarization. Therefore, almost 100% of the Pd isotopes excited to the second excited state become odd mass Pd isotopes. When actually measured, the ratio of the odd mass Pd isotopes occupied in the Pd isotopes excited and ionized in the second excited state was 99.6%.

  In addition, the odd mass Pd isotopes can be selectively excited to the second excited state more easily and efficiently than when two circularly polarized laser beams are used. Details are as follows.

  FIG. 4 is an explanatory diagram in the case of exciting an odd-numbered Pd isotope to a second excited state by two circularly polarized laser beams as in Patent Document 1. Here, it is assumed that the two circularly polarized laser beams rotate in the same direction of vibration of the electric field.

As shown in FIG. 4, the odd-numbered Pd isotope in the ground state has a wavelength λ ₁ = 276 nm due to circular polarization regardless of which z component m _F has the total angular momentum F = 5/2. Excited to the first excited state. This excitation is an excitation in which the z component m _F of the total angular momentum _F is increased by one. There are 15 types of excitation from the ground state to the first excited state as indicated by the number of arrows in FIG. 4 indicating this excitation.

The odd mass Pd isotopes excited to the first excited state are excited to the second excited state by circularly polarized light having a wavelength of λ ₂ = 521 nm. This excitation is an excitation in which the z component m _F of the total angular momentum _F is increased by one. Such excitation from the first excited state to the second excited state can be in 12 ways out of 15 excited in the first excited state, as indicated by the number of arrows in FIG. Therefore, the excitation efficiency is 12/15 = 0.8.

On the other hand, in this embodiment, as shown in FIG. 3, the Pd isotope of the odd-numbered mass number in the ground state has any z component m _F in the total angular momentum F = 5/2. It is excited to the first excitation state by the first linearly polarized laser beam having the wavelength λ ₁ = 276 nm. This excitation is an excitation in which the z component m _F of the total angular momentum F does not change as described above. There are 16 types of excitation from the first excited state to the second excited state as indicated by the number of arrows in FIG.

The odd mass Pd isotopes excited to the second excited state are excited to the second excited state by the second linearly polarized laser beam having the wavelength λ ₂ = 521 nm. This excitation is an excitation in which the z component m _F of the total angular momentum _F is increased or decreased by one. Such excitation from the first excited state to the second excited state can be performed in all 16 ways excited in the first excited state as indicated by the arrows in FIG. Therefore, the excitation efficiency is 16/16 = 1.0.

  The present invention is not limited to the above-described embodiments, and various changes can be made within the scope of the technical idea of the present invention. For example, any one of the following modification examples 1 to 5 may be employed alone, or a plurality of modification examples 1 to 5 may be arbitrarily combined and employed. In this case, the points not described below may be the same as described above.

(Modification 1)
In the above description, the isotope selective excitation apparatus 10 may be an apparatus that selectively excites an isotope having an odd mass number among the odd and even mass isotopes of the same atom other than palladium Pd. . In this case, the wavelengths of the first and second linearly polarized laser beams are changed from the first and second linearly polarized laser beams to the odd-numbered and even-numbered isotopes in the ground state. To a wavelength that is selectively excited in two stages.

(Modification 2)
In FIG. 1, the polarization direction adjusting element 13 may be arranged so as to change the polarization direction of the second linearly polarized laser beam.

(Modification 3)
In FIG. 1, the first and second linearly polarized laser beams are incident on the target substance 1 in opposite directions, but the present invention is not limited to this. That is, even if the first laser irradiation device 3 and the second laser irradiation device 5 are configured such that the first and second linearly polarized laser beams travel on the same straight line and enter the target material 1 in the same direction. Good.

(Modification 4)
FIG. 5A shows a case where the third laser irradiation device 21 has a reflection optical system 33, and shows the vicinity of the target substance 1. In FIG. 5A, the collection device 27 is not shown.
As shown in FIG. 5A, the third laser irradiation device 21 reflects the third laser light so that the third laser light passes through the target substance 1 a plurality of times (preferably many times). A system 33 (multipath optical system) may be included. The reflective optical system 33 may include a plurality of mirrors 33a, 33b, and 33c that reflect the third laser light.

  In the case of such modification example 4, the third laser light does not have to pass through the same path as the first and second linearly polarized laser lights in the target substance 1, and proceeds so as to cross this path. Good.

(Modification 5)
FIG. 5B shows a configuration of the fifth modification in which the isotope selective excitation device 10 includes the reflection optical system 18, and shows the vicinity of the target substance 1. In FIG. 5B, the collection device 27 is not shown.
The reflection optical system 18 reflects the first and second linearly polarized laser beams so that the first and second linearly polarized laser beams pass through the target material 1 a plurality of times (preferably many times). In the example of FIG. 5B, the reflection optical system 18 includes two mirrors 18a and 18b. The mirror 18 a reflects the first linearly polarized laser beam that has passed through the substance 1 toward the substance 1. The mirror 18 b reflects the first linearly polarized laser light reflected by the mirror 18 a and passing through the material 1 toward the material 1. The mirror 18 b reflects the second linearly polarized laser beam that has passed through the substance 1 toward the substance 1. The mirror 18 a reflects the second linearly polarized laser beam reflected by the mirror 18 b and passing through the material 1 toward the material 1.

  The first and second linearly polarized laser beams travel on the same path when passing through the target substance 1 only a plurality of times by the reflection optical system 18. At each position in the path, the polarization direction of the first linearly polarized laser beam is orthogonal to the polarization direction of the second linearly polarized laser beam.

  Even in the multiple reflections described above, the degree of polarization of the first and second linearly polarized laser beams is kept high, so that the odd mass Pd isotopes can be selectively excited into the second excited state at a high rate.

  In the example of FIG. 5B, the third laser light is guided by the above-described reflection optical system 33, but the reflection optical system 33 may be omitted. In this case, preferably, the third laser light travels in the same direction along the same path as the first or second linearly polarized laser light in a state where it overlaps with the first or second linearly polarized laser light, The target material 1 passes through the reflection optical system 18 a plurality of times.

  In the example of FIG. 5B, the first and second linearly polarized laser beams travel in opposite directions. However, the first and second linearly polarized laser beams are selectively excited so as to pass through the target substance 1 only a plurality of times by the reflecting optical system 18 while traveling in the same direction in the same direction in a state where they overlap each other. The apparatus 10 may be configured.

DESCRIPTION OF SYMBOLS 1 Target substance, 2 Crucible, 3 1st laser irradiation apparatus, 5 2nd laser irradiation apparatus, 7 Laser emission part, 9a, 9b Mirror, 10 Isotope selective excitation apparatus, 11 Polarization element, 13 Polarization direction adjustment element, DESCRIPTION OF SYMBOLS 15 Laser emission part, 17a, 17b Mirror, 18 Reflection optical system, 18a, 18b Mirror, 19 Polarization element, 20 Ionization device, 21 3rd laser irradiation apparatus, 23 Laser emission part, 25 Mirror (dichroic mirror), 27 Collection apparatus , 28 Metal electrode, 29 Wire mesh electrode, 31 Collection substrate, 33 Reflective optical system, 33a, 33b, 33c Mirror

Claims (4)

An isotope selective excitation method for selectively exciting odd-numbered isotopes among odd-numbered and even-numbered isotopes of the same atom,
(A) generating first and second linearly polarized laser beams;
(B) irradiating the target substance containing isotopes of odd and even mass numbers with the first and second linearly polarized laser beams,
In (B), at the position of the target substance, the polarization direction of the first linearly polarized laser beam is orthogonal to the polarization direction of the second linearly polarized laser beam,
The wavelengths of the first and second linearly polarized laser beams are selected from two odd-numbered and even-numbered isotopes by using the first and second linearly polarized laser beams. An isotope selective excitation method set to a wavelength to be excited. The isotope is an isotope of a palladium atom;
The isotope selective excitation method according to claim 1, wherein the wavelengths of the first and second linearly polarized laser beams are 276 nm and 521 nm, respectively. An isotope selective excitation apparatus that selectively excites odd-numbered isotopes among odd-numbered and even-numbered isotopes of the same atom,
A first laser irradiation apparatus for generating a first linearly polarized laser beam and irradiating the target substance containing isotopes of odd and even mass numbers with the first linearly polarized laser beam;
A second laser irradiation device that generates a second linearly polarized laser beam and irradiates the target material with the second linearly polarized laser beam,
The first laser irradiation device and the second laser irradiation device are configured so that the polarization direction of the first linearly polarized laser beam is orthogonal to the polarization direction of the second linearly polarized laser beam at the position of the target substance. ,
The wavelengths of the first and second linearly polarized laser beams are selected from two odd-numbered and even-numbered isotopes by using the first and second linearly polarized laser beams. An isotope selective excitation device set to the wavelength to be excited. The isotope is an isotope of a palladium atom;
The isotope selective excitation apparatus according to claim 3, wherein the wavelengths of the first and second linearly polarized laser beams are 276 nm and 521 nm, respectively.

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