JP3125173B2 - Method and apparatus for selectively collecting low energy charged particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of selectively collecting low energy charged particles (several eV to several hundreds eV) represented by a positron by changing the direction of movement of the charged particles and selectively collecting the low energy charged particles. Related to the device.

[0002]

2. Description of the Related Art In recent years, low energy charged particles such as positrons e ⁺ are obtained from protons p by utilizing β ⁺ decay, which is a conversion reaction of nuclear nucleons, using a general particle accelerator such as a cyclotron accelerator. Technology is being developed. This particle accelerator arranged target set in particle emission portion, decelerated by impinging protons p is accelerated emitted from the accelerator by the target set, to obtain a positron e ⁺ from protons p positron e ⁺ of the mother particle . Thus, the target set for obtaining the positron e ⁺ from the proton p by the collision is formed by laminating the aluminum material layer and the tungsten material layer. The aluminum material layer is provided on the collision surface side, and the tungsten material layer is provided on the particle extraction surface side. It is arranged to face. By the way, these technologies were recently developed,
The related technology has already been filed for patent.

Meanwhile, a technique of selectively collecting the positrons by changing the direction of movement of the e ⁺ has been studied. In such a case, as shown in FIG.
Is connected to a particle collection tube to form a selective branch collection device for positron e ⁺ . In the case of the selective branch collection device, the positron e ⁺ is obtained after the proton p is branched and selected in the particle collection tube provided in the particle acceleration chamber.

As shown in FIG. 5, the particle collecting tube used here has a main tube extending in a uniaxial direction for guiding protons p moving in a predetermined direction, and intersects with the uniaxial direction of the main tube. And two branch pipes extending from one end of the main pipe in a direction different from the uniaxial direction.

In this particle collection tube, the other end of the main tube is connected to the particle emission portion of the particle accelerator 1 via a flange F1, and two branch tubes for extracting positrons e ⁺ from the beam of the protons p are provided. Target set T1, T
2 are deployed. Further, the branch pipe provided with the target set T1 is connected to another pipe extending outside the particle acceleration chamber through the wall of the particle acceleration chamber via the flange F2, and the branch pipe provided with the target set T2 is also connected to the flange F3. It is connected to another tube extending outside the particle acceleration chamber through the wall of the particle acceleration chamber. Further, a pair of bending magnets 2a (upper side in the figure) and 2b as magnetic field generating means for promoting the motion of charged particles for generating a magnetic field in the main pipe are provided around the main pipe.
(The lower side in the figure). These bending magnets 2a and 2b are defined on a plane perpendicular to the axial direction of the main pipe, and are provided so as to generate a magnetic field in a direction orthogonal to the axial direction. in this way,
When the bending magnets 2a and 2b are used, the beam of the proton p can be guided as shown by Fleming's left-hand rule.

The selective branching of the positron e ⁺ by the selective branch collecting device will be described. The protons p emitted from the particle accelerator 1 are guided from the point A to the main tube of the particle collecting tube via the flange F1. The direction of movement of the p beam is changed in one direction in a predetermined axial direction on a plane perpendicular to one axial direction of the main pipe by receiving a force according to Fleming's left hand rule by a magnetic field generated between the pair of bending magnets 2a and 2b. . Thereby, the beam of the proton p is bent and guided into the branch pipe including the target set T1. The beam of the proton p collides with the target set T1 and is decelerated. A beam of the positron e ⁺ is obtained from the proton p by the target set T1, and emitted to the point B side via the flange F2.

Further, the beam of the proton p is set to the target set T
In the case where the magnetic flux is guided into the branch pipe provided with the bending magnets 2, the bending magnets 2a and 2b are made to have opposite magnetic polarities and opposite directions of the generated magnetic field. In this case, the beam of the proton p collides with the target set T2 and is decelerated. A beam of the positron e ⁺ is obtained from the proton p by the target set T2 and emitted to the point C side via the flange F3.

[0008]

In the case of the selective branch collecting apparatus described above, the particle collecting tube is arranged in the particle accelerating chamber and the positron e ⁺ is taken out in the particle collecting tube. As a result, the occupied space of the entire apparatus becomes too large.

Further, the bending magnet used around the main tube of the particle collection tube needs to change the direction of movement of the beam of protons p in a high energy state accelerated at a high speed, so that a strong magnetic field must be generated. Must. Furthermore,
The target set for obtaining the positron e ⁺ is also expensive, and there is a problem that the cost of the entire apparatus becomes high in a configuration in which an expensive target set is arranged in each branch pipe.

[0010] In addition, in the case of the above-mentioned selected branch collecting device, after a beam of protons p high-energy state is branched by particle acceleration chamber, since it is to obtain a positron e ^+, positrons particle acceleration outdoor e ⁺ Is used, the radiation direction of the positron e ⁺ beam is easily limited, and the positron e ⁺
There is also inconvenience that it is difficult to take out ⁺ .

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its technical problem is that a relatively small occupied space can be used at low cost, and low-energy charged particles can be selected in any direction. It is an object of the present invention to provide a selective branch collection method and a selective branch collection device for low energy charged particles that can be collectively collected.

[0012]

According to the present invention, a low-energy charged particle that moves in a predetermined direction using a first magnetic field generated by a first solenoid coil or a first Helmholtz coil extends in a uniaxial direction. By moving the low-energy charged particles in the main pipe using a second magnetic field in the plurality of branch pipes generated by the second solenoid coil or the second Helmholtz coil. A method is provided for selectively collecting low energy charged particles that selectively directs low energy charged particles from the main pipe to one of the branch pipes.

According to the present invention, a low-energy charged particle moving in a predetermined direction is guided into a main pipe extending in a uniaxial direction using a first magnetic field generated by a solenoid coil or a Helmholtz coil, and generated by a steering coil. Changing the direction of movement of the low-energy charged particles in the main pipe by using a third magnetic field that intersects the uniaxial direction in the main pipe and that is different from the uniaxial direction, thereby changing the low-energy charged particles. A method of selectively branching and collecting low-energy charged particles that is selectively guided from the main pipe to one of a plurality of branch pipes is obtained.

According to the present invention, on the other hand, the main pipe extending in one axis direction and guiding the low-energy charged particles moving in a predetermined direction, and the main pipe intersecting with the one axis direction and being different from the one axis direction. A plurality of branch pipes extending from one end, a magnetic field generating means provided around the main pipe, and a magnetic field generating means for generating a magnetic field in the main pipe for guiding low-energy charged particles from the main pipe to the plurality of branch pipes; Power supply selecting means for selectively supplying power to the generating means, wherein the magnetic field generating means is wound around the outer peripheral surface of the main pipe, and the first solenoid coil or the first solenoid coil for generating the first magnetic field. A Helmholtz coil and two coils which are respectively provided in the vicinity of the first solenoid coil or the plurality of branch pipes around the first Helmholtz coil and which are orthogonal to each other on a plane perpendicular to the uniaxial direction. Low energy selection branch collecting apparatus of charged particles and a plurality of steering coil for generating a third magnetic field in the axial direction is obtained.

Further, according to the present invention, in the selective branch collection device for low-energy charged particles, the magnetic field generating means includes:
While being wound around the outer peripheral surface of each of the plurality of branch pipes,
A second solenoid coil or a second solenoid for generating a second magnetic field;
And a selective branch collection device for low-energy charged particles including the Helmholtz coil.

On the other hand, according to the present invention, a main pipe extending in one axis direction and guiding low-energy charged particles moving in a predetermined direction, and one end of the main pipe crossing the one axis direction and in a direction different from the one axis direction. A plurality of branch pipes extending from the main pipe, first magnetic field generating means for generating a first magnetic field into the main pipe, and a first magnetic field generating means for generating a first magnetic field into the main pipe; In addition to being provided in
The plurality of second magnetic field generating means for generating a second magnetic field in each of the plurality of branch pipes, the first magnetic field generating means, and one of the plurality of second magnetic field generating means are selectively provided. Power supply selection means for supplying power, wherein the first magnetic field generation means is a first solenoid coil or a first Helmholtz coil wound around the outer peripheral surface of the main pipe, and a plurality of second magnetic field generation means.
The magnetic field generating means of the present invention provides a selective branch collection device for low-energy charged particles, which is a plurality of second solenoid coils or a second Helmholtz coil wound around each of the outer peripheral surfaces of the plurality of branch pipes.

Further, according to the present invention, in any one of the selective branch collection devices for low energy charged particles described above, the other end of the main pipe is connected to a particle emission portion of a particle accelerator that emits base particles of low energy charged particles. The main pipe extends through the particle acceleration chamber wall where the particle accelerator is installed, and the plurality of branch pipes are taken out of the particle acceleration chamber. A low-energy charged particle selective branch collection device provided with a target set for obtaining low-energy charged particles from particles is obtained.

Further, according to the present invention, in any one of the selective branch collection devices for low-energy charged particles described above, the base particles of low-energy charged particles are caused to collide with the other end of the main pipe so as to collide with the base particles. Thus, a selective branch collection device for low energy charged particles provided with a radiation member for obtaining the low energy charged particles is obtained.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below in detail with reference to the accompanying drawings, in which a selective branch collecting method and a selective branch collecting apparatus for low energy charged particles of the present invention are described.

First, the outline of the selective branch collection method for low energy charged particles of the present invention will be briefly described. One mode of this selective branch collection method is to extend a positron e ⁺ , which is a low-energy charged particle that moves in a predetermined direction using a first magnetic field generated by a first solenoid coil or a first Helmholtz coil, in one axial direction. main pipe to lead the, by changing the positron e ⁺ direction of movement of the second solenoid coil or the second main pipe using a magnetic field of a plurality of branch tubes generated by second Helmholtz coils, the positron e ⁺ The main pipe is selectively guided to one of a plurality of branch pipes.

In another mode of the selective branch collection method, a positron e ⁺ , which is a low-energy charged particle that moves in a predetermined direction using a first magnetic field generated by a solenoid coil or a Helmholtz coil, extends in a uniaxial direction. guided into the main pipe, by crossing the axial direction of the main pipe which is generated in a steering coil, changing the direction of motion of the positron e ⁺ in and the main using a third magnetic field uniaxial direction different, positron e ⁺ From the main pipe to one of the plurality of branch pipes.

Further, when these selective branch collection methods are used together, by adjusting the strength and direction of the generated magnetic field, the direction of the force applied to the positron e ⁺ with the generation of the magnetic field can be finely adjusted. Due to an increase in the stimulatory activity for ⁺ , the branch selectivity is more efficient than taking a single form.

FIG. 1 is a block diagram showing a basic configuration of an apparatus for selectively collecting and collecting low-energy charged particles according to an embodiment of the present invention to which the above-described selective branch collection method is applied.

As shown in the drawing, the selective branch collection device includes a particle accelerator 1 such as a cyclotron having a particle emission unit, and a particle collection tube is connected to the particle emission unit. Only one target set T is provided in the particle emission section of the particle accelerator 1. The illustrated particle collection tube has a main tube extending in one axial direction for guiding a positron e ⁺ moving in a predetermined direction, and one end of the main tube intersecting with the one axial direction of the main tube and different from the one axial direction. And two branch pipes extending from the second branch pipe.

The other end of the main pipe of the particle collection pipe is connected to a particle discharge section of the particle accelerator 1 via a flange F,
The extending part of the main pipe penetrates the particle acceleration chamber wall in which the particle accelerator 1 is installed, and the two branch pipes are taken out of the particle acceleration chamber. Here, the ends of the two branch pipes are connected to the required utilization devices 5, 6, respectively. Examples of the utilization devices 5 and 6 include a mass analyzer and a positron re-emission microscope.

A magnetic field generator 20 for generating a magnetic field for guiding the low-energy charged particles from the main pipe to the respective branch pipes is provided around the main pipe, and a coupling-side portion of the two branch pipes is provided. The magnetic field generating units 21 and 2 that generate magnetic fields in the respective branch pipes
2 are provided. Further, a power supply adjustment supply unit 3 for supplying power is connected to the magnetic field generation unit 20, and power supply selection supply means 4 for selectively supplying power to one of the magnetic field generation units 21 and 22 is provided to the magnetic field generation units 21 and 22. Is connected. The combination of the power supply adjustment supply unit 3 and the power supply selection supply unit 4 functions as a power supply selection supply unit that selectively supplies power to the magnetic field generation unit 20 and one of the magnetic field generation units 21 and 22.

That is, in this selective branch collection device, since the positron e ⁺ is obtained in the particle emission part of the particle accelerator 1, the selective branch of the positron e ⁺ is branched (each branch) of the particle collection tube arranged outside the particle acceleration chamber. (Branch pipe).

FIGS. 2 (a) to 2 (c) show the configuration around the particle collection tube in the selective branch collection device.
FIG. 1A shows a top view, FIG. 1B shows a side view thereof, and FIG. 1C shows a cross-sectional view taken along the line EE ′ of FIG. 1A. .

Referring to each figure, the magnetic field generating unit 20 is wound around the outer peripheral surface of the main pipe, generates a first magnetic field, and includes a first solenoid coil S1 and a first solenoid coil S1. Steering coils ST1, ST2, ST3, and ST4, which are provided adjacent to the two neighboring portions near the branch pipe and generate a third magnetic field, respectively.

Of these steering coils, ST
1 and ST2 form one pair, and ST3 and ST2
4 is the other pair. Each steering coil ST
1, ST2, ST3, and ST4 are wound in a race track shape, and a pair of steering coils ST1 and S4.
T2 generates a magnetic field (third magnetic field) in one axis direction orthogonal to the one axis direction on a plane perpendicular to the one axis direction of the main pipe, and the steering coils ST3 and ST4 forming the other pair include: Steering coil ST1,
A magnetic field (third magnetic field) is generated in a direction orthogonal to the magnetic field generated by ST2 and one axis direction of the main tube. In this configuration, the magnetic field generated in the directions corresponding to the X axis and the Y axis inside the main pipe by the steering coils of each pair can be controlled by adjusting the current supplied to the steering coils of each pair.

Therefore, in the above-described power supply adjustment supply unit 3,
It has a structure capable of adjusting the distribution of power supply to the pair of steering coils ST1 and ST2 and the other pair of steering coils ST3 and ST4. For example, one of these pairs ST1 and ST2, or the other of them. Power can be supplied by selecting either ST3 or ST4 of the pair.

In the illustrated example, two magnetic field generating units 2 are provided.
Reference numerals 1 and 22 are wound around the outer peripheral surfaces of the two branch pipes, respectively, and include two second solenoid coils S2 and S3 that generate a second magnetic field.

Next, a case where the positron e ⁺ is selectively branched to the utilization device 5 by the selective branch collection device will be described.
In this case, however, the steering coils ST1, ST2, ST3, and ST4 are initially set by the power supply adjustment supply unit 3.
And the current supplied to the first solenoid coil S1 is adjusted and set (for example, a larger current is supplied to ST1 and ST2 than ST3 and ST4). Therefore, the second solenoid coil S2 is energized, and the third solenoid coil S3 is not energized.

Under these conditions, when the protons p emitted from the particle accelerator 1 collide with the target set T in the particle emitting portion, the positron e ^{+, which} is slower than the protons p, is extracted in the form of a beam. The beam of the positron e ⁺ is guided through the flange F into the main tube of the particle collection tube. The beam of the positron e ⁺ is generated by a combined magnetic field generated by the steering coils ST1 to ST4 constituting the magnetic field generation unit 20 and a magnetic field generated by the first solenoid coil S1 in a direction different from the one axial direction of the main pipe. Then, in this example, it is deflected to the utilization device 5 side. Thereby, the positron e ⁺ beam is emitted to the utilization device 5 side.

When the positron e ⁺ is selectively branched to the utilization device 6, the steering coils ST 1 and ST 2, ST 3 and ST 4 are initially supplied by the power supply adjusting and supplying unit 3.
And the current supplied to the first solenoid coil S1 is adjusted (for example, ST3 rather than ST1 and ST2).
And a large current is supplied to ST4), the third solenoid coil S3 is energized by the power supply selection supply unit 4, and the second solenoid coil S2 is supplied.
Is not energized.

Thus, the positron e guided into the main pipe
^{The +} beam is guided into the branch pipe by the third magnetic field (synthetic magnetic field) generated by the steering coils ST1 to ST4 and the first magnetic field generated by the first solenoid coil S1. Thereby, the positron e ⁺ beam is emitted to the utilization device 6 side.

By the way, if the steering coils ST1 to ST4 in the magnetic field generator 20 provided around the main tube in the particle collecting tube of the above-described embodiment are removed, a selective branch collecting device according to another embodiment of the present invention is constituted. be able to.

FIG. 3 shows the configuration around the particle collection tube in this case. As is clear from the comparison with the previous embodiment, the periphery of the particle collection tube is
0, the steering coils ST1 to ST4 are removed and only the first solenoid coil S1 is used. In this example, the first solenoid coil S1 is used as a first magnetic field generating unit for generating a first magnetic field into the main pipe, and a power supply unit for supplying power to the first magnetic field generating unit is connected to the power supply adjustment supply unit 3 earlier. The configuration is used instead.

Also in the case of this selective branch collection device, power is supplied to the first solenoid coil S1 by the first magnetic field generation unit, and the power is selectively supplied to the second solenoid coil S1 by the power supply selection supply unit 4.
Solenoid coil S2 or third solenoid coil S
3 by selectively supplying power, the positron e ⁺ is generated by the first magnetic field generated by the first solenoid coil S1 and the second magnetic field generated by the second solenoid coil S2 or the third solenoid coil S3. The beam can be selectively branched to the utilization devices 5 and 6 side.

On the other hand, in each of the above-described embodiments, the target set is arranged in the particle discharge section of the particle accelerator 1, and the other end of the main pipe in the particle collection tube is connected to the particle discharge section. The radiation member can be incorporated into the other end of the main tube to form a particle collection tube. The radiating member here is a proton p which is naturally radiated by nuclear β ⁺ decay in a radioisotope such as ²² N.
Used to obtain the positron e ⁺ from Also in this case, by arranging the magnetic field generator as shown in FIGS. 2 and 3 with respect to the particle collection tube, the positron e ⁺ beam can be selectively branched to the utilization devices 5 and 6.

In each of the embodiments described above, the configuration in which the particle collection pipe is branched from the main pipe to two branch pipes has been described. However, the number of branch pipes may be three or more. However, when using a particle collection tube having three or more branch tubes,
Although it is necessary to generate a magnetic field for guiding the positron e ⁺ beam into each branch pipe, the magnetic field required for branching can be obtained by optimizing the current from the power supply and adjustment unit 3. Further, a Helmholtz coil may be used instead of the solenoid coils S1, S2, S3 used in the particle collection tube of each embodiment. Furthermore, selection branch collection method and selection branch collecting apparatus of the present invention is applicable to any low-energy charged particles, except in positron e ⁺ proton p beta ^- intended for the beam ^- electron e obtained by disintegration Can be selectively branched. Therefore, the present invention is not limited to the selective branch collection device targeting only the positron e ⁺ .

[0042]

As described above, according to the present invention, it is possible to efficiently perform selective branch collection of low-energy charged particles with a simple and inexpensive configuration, so that the use value of low-energy charged particles is further enhanced. Further, in the case of the selective branch collection device, the distribution of the magnetic field is changed by the magnetic field generation unit so that the low energy charged particles can be selectively branched in an arbitrary direction outside the particle acceleration chamber. The energy charged particles can be selected for time sharing and used for multiple purposes. As a result, the positron e ⁺ can be selectively branched to an adjacent place outside the particle acceleration chamber, which could not be implemented conventionally, and various utilization devices can be irradiated with the positron e ⁺ beam. Therefore, devices used for inspection of lattice defects, mass spectrometry, or positron re-emission microscope for various materials can be arranged, and can be used for various purposes. For example, when used for analysis of a semiconductor device, the state of the first atomic layer can be easily grasped from the state of diffraction of the positron e ⁺ , which is extremely effective. Furthermore, it is possible to easily construct a system in which such an analyzer coexists with a mass spectrometer or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a positron e ⁺ selective branch collection device according to an embodiment of the present invention.

FIGS. 2A and 2B show a configuration of a peripheral part of a particle collection tube which is a main part of the selective branch collection device shown in FIG. 1, wherein FIG. 2A is a top view, FIG. 2B is a side view, and FIG. EE in FIG.
FIG.

FIG. 3 is a top view showing a configuration of a peripheral part of a particle collection tube which is a main part of a selective branch collection apparatus for a positron e ^{+ according} to another embodiment of the present invention.

FIG. 4 is a block diagram showing a basic configuration of a positron e ⁺ selective branch collection device proposed in the prior art.

FIG. 5 is a top view showing a configuration of a peripheral part of a particle collection tube which is a main part of the selective branch collection device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Particle accelerator 2a, 2b Bending magnet 3 Power supply adjustment supply part 4 Power supply selection supply part 5, 6 Utilization device 20, 21, 22 Magnetic field generation part F, F1, F2, F3 Flange T, T1, T2 Target set S1, S2 S3 Solenoid coil ST1, ST2, ST3, ST4 Steering coil

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05H 7/00 G21K 1/093

Claims (7)

(57) [Claims] 1. A low-energy charged particle moving in a predetermined direction using a first magnetic field generated by a first solenoid coil or a first Helmholtz coil is guided into a uniaxially extending main pipe, and a second solenoid is provided. A second magnetic field in a plurality of branch tubes generated by a coil or a second Helmholtz coil is used to change the direction of movement of the low-energy charged particles in the main tube, thereby moving the low-energy charged particles from the main tube to the plurality of tubes. Selectively collecting the low-energy charged particles into one of the branch pipes. 2. A low-energy charged particle moving in a predetermined direction using a first magnetic field generated by a solenoid coil or a Helmholtz coil is guided into a uniaxially extending main pipe,
By changing the direction of motion of the low-energy charged particles in the main pipe using a third magnetic field generated by a steering coil and intersecting with the uniaxial direction in the main pipe and in a direction different from the uniaxial direction, A method of selectively branching and collecting low energy charged particles, comprising selectively guiding energy charged particles from the main pipe to one of a plurality of branch pipes. 3. A main pipe extending in one axial direction and guiding low-energy charged particles moving in a predetermined direction, and a plurality of main pipes intersecting with the one axial direction and extending from one end of the main pipe in a direction different from the one axial direction. And a magnetic field generating means provided around the main pipe, for generating a magnetic field in the main pipe for guiding the low-energy charged particles from the main pipe to the plurality of branch pipes, and the magnetic field generating means Power supply selection supply means for selectively supplying power to the main pipe, wherein the magnetic field generation means is wound around the outer peripheral surface of the main pipe to generate a first magnetic field, or a first solenoid coil or a first Helmholtz coil And a portion provided around the first solenoid coil or the first Helmholtz coil and in the vicinity of the plurality of branch pipes, respectively, and is perpendicular to each other on a plane perpendicular to the uniaxial direction. And a plurality of steering coils for generating a third magnetic field in two intersecting axial directions. 4. The selective branch collection device for low energy charged particles according to claim 3, wherein the magnetic field generating means is wound around the outer peripheral surface of each of the plurality of branch tubes.
A second solenoid coil or a second solenoid for generating a second magnetic field;
And a low-energy charged particle selective branching device comprising a Helmholtz coil. 5. A main pipe extending in one axial direction and guiding low energy charged particles moving in a predetermined direction, and a plurality of main pipes intersecting with the one axial direction and extending from one end of the main pipe in a direction different from the one axial direction. And a first pipe that is provided around the main pipe and generates a first magnetic field into the main pipe.
Magnetic field generating means, and a plurality of second magnetic field generating means which are provided around each of the plurality of branch pipes adjacent to the coupling side portion and generate a second magnetic field in each of the plurality of branch pipes. Power supply selection supply means for selectively supplying power to one of the first magnetic field generation means and one of the plurality of second magnetic field generation means, wherein the first magnetic field generation means comprises: A first solenoid coil or a first Helmholtz coil wound on the outer circumferential surface of the main pipe, wherein the plurality of second magnetic field generating means are wound on each of the outer circumferential faces of the plurality of branch pipes; And the second solenoid coil or the second Helmholtz coil. 6. The selective branch collection device for low-energy charged particles according to claim 3, wherein the other end of the main pipe is a particle of a particle accelerator that emits base particles of the low-energy charged particles. Connected to a discharge part, the extending part of the main pipe penetrates a particle acceleration chamber wall in which the particle accelerator is installed, the plurality of branch pipes are taken out of the particle acceleration chamber, and further, the inside of the particle discharge part is A selective branch collection device for low-energy charged particles, wherein a target set for obtaining the low-energy charged particles from the parent particles by decelerating the base particles is provided. 7. The selective branch collection device for low-energy charged particles according to claim 3, wherein base particles of the low-energy charged particles collide with the other end of the main pipe. And a radiating member for obtaining the low-energy charged particles from the base particles.