JP2007101367A - Electrode for quantum beam monitor and quantum beam monitor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for a quantum beam monitor superior in heat resistivity, radiation resistivity and secondary electron discharge characteristics. <P>SOLUTION: The electrode 1 for quantum beam monitor of this invention includes a monitor target 21 on which a plurality of ribbon shape carbon graphite thin films 210 are put with a specific interval along a direction. The carbon graphite thin film 210 desirably has a thickness of 0.5 to 100 μm and a width of 0.05 to 50 mm, and the distance between adjacent carbon graphite thin films 210 is desired to be of 0.01 to 100 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a quantum beam monitor that uses secondary electron emission of a monitor target, in particular, a quantum beam monitor electrode that can be suitably used for a beam profile monitor, a manufacturing method thereof, a quantum beam monitor device including the electrode, and a The present invention relates to a method for measuring a quantum beam profile using a laser.

  Various beam monitors are attached to the accelerator as monitors related to normal operation monitoring and beam line performance improvement (improvement of beam transport efficiency) (for example, see Patent Document 1 below). Among these beam monitors, a secondary electron emission type beam profile monitor is used as a monitor for measuring the cross-sectional shape and two-dimensional density distribution of the transported beam and adjusting the accelerator parameters.

  Such a beam profile monitor has a monitor target that is formed by depositing a metal film such as aluminum on a conductive film such as a metal wire or a backing film made of a thin film of a polymer compound such as polyimide or polypropylene. The secondary electron emission of the monitor target is used (for example, see Non-Patent Document 1 below).

JP-A-6-251900 Akio Higashi, et al. "Secondary-Electron-Emission Type of Beam Profile Monitor for the HIMAC-Injector (6 MeV / u)", Proceedings of The12th Symposium on Accelerator Science and Technology, Wako, Japan 1999.

  By the way, when using a conductive wire as a monitor target as in the former, it is necessary to use a high melting point material such as tungsten in order to ensure heat resistance. Since such a material has a high density, the beam loss is large. Had the problem of becoming. When the metal film is vapor-deposited on the backing film as in the latter and used as a monitor target, there are problems such as melting of the backing film and peeling of the vapor-deposited metal film when the beam intensity is increased. Although it is conceivable to use a thin film of beryllium, it has a relatively low melting point (1280 ° C.), is expensive, and is difficult to handle and manufacture. In addition, when the thickness of the film is 5 μm or less, a film having a length of 50 mm or more cannot be produced.

  The present invention has been made in view of the above problems, and includes an electrode for a quantum beam monitor excellent in heat resistance, radiation resistance and secondary electron emission characteristics, and a profile of a high-intensity quantum beam comprising the electrode. A quantum beam monitor device capable of measuring a beam loss with high sensitivity, a method of measuring a quantum beam profile using the device, and a manufacturing method capable of suitably manufacturing the quantum beam monitor electrode The purpose is to do.

  The present invention achieves the above-mentioned object by providing a quantum beam monitoring electrode having a monitor target in which a plurality of ribbon-like carbon graphite thin films are arranged in parallel in one direction at predetermined intervals. is there.

  The present invention also relates to the method of manufacturing a quantum beam monitor electrode according to the present invention, wherein a carbon graphite thin film is fixed to a frame substrate having a quantum beam passage space so as to straddle the passage space, and then the carbon graphite The present invention provides a method for manufacturing an electrode for quantum beam monitoring, in which a thin film is irradiated with a laser beam, and the carbon graphite thin film is processed into a plurality of ribbon shapes to form the target.

  Furthermore, the present invention provides a quantum beam monitor device comprising the quantum beam monitor electrode of the present invention.

  The present invention also provides a method of measuring a quantum beam profile using the quantum beam monitor device of the present invention.

  The quantum beam monitor electrode of the present invention is excellent in heat resistance and radiation resistance, and also in secondary electron emission characteristics. Further, according to the quantum beam monitor apparatus and the beam profile measuring method using the same according to the present invention, it is possible to measure a profile of a high-intensity quantum beam with high sensitivity while suppressing a beam loss low. Furthermore, according to the method for manufacturing a quantum beam monitor electrode of the present invention, it is possible to preferably manufacture a quantum beam monitor electrode that exhibits the above-described effects.

The present invention will be described below based on preferred embodiments with reference to the drawings.
FIG. 1 schematically shows an embodiment in which the quantum beam monitor apparatus of the present invention is applied to a charged particle beam profile monitor apparatus (hereinafter also simply referred to as a beam monitor apparatus). In FIG. 1, reference numeral 1 denotes a beam monitor device, and 10 denotes a vacuum chamber in which the beam monitor device is set.

  As shown in FIG. 1, the beam monitor apparatus 1 of this embodiment includes a charged particle beam monitor electrode (quantum beam monitor electrode: hereinafter also simply referred to as a monitor electrode) 2 and a front and rear of the monitor electrode 2. A pair of secondary electron capturing electrodes (hereinafter also simply referred to as capturing electrodes) 3, a charge integrator 4 connected to the monitoring electrode 2, and a DC power supply device connected to the capturing electrode 3 5.

  As shown in FIG. 2, the monitoring electrode 2 includes a monitor target 21 in which a plurality of ribbon-like carbon graphite thin films 210 are arranged in parallel along the horizontal direction at predetermined intervals. The carbon graphite thin film 210 is fixed to the connection terminal of the printed wiring 23 provided on the insulating frame substrate 22 so as to be conductive. In the figure, the monitor target 21 and the printed wiring are shown corresponding to five carbon graphite thin films for convenience, but the ribbon-like carbon graphite thin films are 10 to 100 depending on the beam diameter, the width of the thin film, the interval, and the like. It is installed side by side. Although not shown in the figure, the frame substrate 22 is provided with a printed wiring for the ground.

The frame substrate 22 of the monitor electrode 2 is provided with a window 220 for forming a charged particle beam passage space S2, and the carbon graphite thin film 210 constituting the monitor target 21 is printed on the printed wiring 23 so as to straddle the passage space S2. It is fixed between the terminals. The carbon graphite thin film 210 and the terminal are fixed with a conductive adhesive for vacuum. The monitoring electrode 2 to which the carbon graphite thin film 210 is fixed with a conductive adhesive for vacuum is preferably 1 × 10 ^{− in} order to keep the surface of the carbon graphite thin film 210 clean without being affected by molecular adsorption or the like. It is desirable to use in a vacuum environment of ³ Pa or less, more preferably 1 × 10 ⁻⁵ Pa or less, and particularly preferably 1 × 10 ⁻⁷ Pa or less. From this, the conductive adhesive for vacuum is It is preferable to use an appropriate amount of an adhesive that does not deteriorate the vacuum environment.

  The width W of each carbon graphite thin film 210 is a viewpoint of measurement sensitivity, thin film processability, resolution, and self-supporting ability (hereinafter simply referred to as self-supporting ability) so that it can be fixed between terminals as a monitor target without bending. 0.2 to 2.0 mm is preferable, and 0.5 to 1.5 mm is more preferable.

  The distance D between the adjacent carbon graphite thin films 210 is preferably 0.2 to 1.0 mm, more preferably 0.5 to 1.0 mm in consideration of measurement sensitivity and signal interference between adjacent thin films.

  The length of each carbon graphite thin film 210 is preferably 20 to 300 mm, more preferably 50 to 150 mm in consideration of measurement sensitivity, thin film processability, self-supporting property, and effective diameter of the beam traveling space.

  The thickness of each carbon graphite thin film 210 can be used in the range of 0.5 to 100 μm. If the self-supporting property can be satisfied, it is preferably as thin as possible from the viewpoint of beam loss, preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and particularly preferably 0.5 to 2.5 μm.

  The melting point of the carbon graphite thin film 210 is preferably as high as possible from the viewpoint of heat resistance, and particularly preferably 3000 ° C. or higher.

The thermal conductivity of the carbon graphite thin film 210 is preferably as high as possible from the viewpoint of stable operation of the beam monitoring apparatus during irradiation, and it is particularly preferable that the thermal conductivity in the thin film plane is higher.
Further, the thermal expansion coefficient of the carbon graphite thin film 210 is preferably small from the viewpoint of the stable operation of the beam monitor device 1 and the accuracy of the measurement position, and more preferably the thermal expansion coefficient in the thin film surface direction is particularly small.
From the above viewpoint, the carbon graphite thin film preferably has a carbon hexagonal network surface constituting the graphite crystal oriented in parallel with the surface of the thin film.

  The graphite interlayer distance of the carbon graphite thin film 210 is preferably from 0.332 to 0.340 nm, particularly preferably from 0.332 to 0.336 nm, from the viewpoint of chemical stability, electron conductivity and thermal conductivity. 0.335 nm is more preferable. When the graphite interlayer distance is large, the electron conductivity is lowered, so that the detection sensitivity is deteriorated. In addition, the efficiency of releasing the accumulated heat by the energy transfer with the charged particle beam to be irradiated is deteriorated. Furthermore, the deterioration of chemical stability, particularly oxidation resistance, is not preferable because the progress of deterioration due to a slight amount of gas, particularly oxygen molecules, is accelerated during beam irradiation. Further, it is difficult to manufacture a graphite having a graphite interlayer distance of less than 0.332 nm.

  As the carbon graphite thin film 210, for example, a highly oriented graphite layered sheet described in paragraphs [0012] to [0032] of JP-A-2002-308611 can be used.

  The frame substrate 22 is not particularly limited as long as it has insulating properties, radiation resistance, and low gas emission characteristics in a vacuum. The material of the frame substrate 22 is preferably ceramics, and alumina and silicon nitride are particularly preferable in consideration of strength and heat conduction.

  Individual terminals for reading out the printed wiring 23 are collected in the apron portion 221 of the frame substrate 22. The individual terminals for reading out the printed wiring 23 are connected to the charge integrator 4 (see FIG. 1) for each carbon graphite thin film 210.

The monitor electrode 2 can be manufactured by the following procedure.
First, an adhesive is applied to the terminal for fixing the carbon graphite thin film in the printed wiring 23 of the frame substrate 22, and the carbon graphite thin film of each leaf is fixed so as to straddle the passage space S <b> 2 of the frame substrate 22. At this time, the adhesive is solidified with an appropriate tension applied.

  Thereafter, the carbon graphite thin film is irradiated with a laser beam, and the carbon graphite thin film is processed into a plurality of ribbon shapes to form the monitor target 21. The focal position of the laser beam is adjusted to the surface of the thin film so as not to leave a processing mark on the frame substrate 22. The laser to be irradiated is preferably a laser having a wavelength in the ultraviolet region in consideration of workability, while a YAG laser (infrared region having a wavelength of about 1.1 μm) is preferable in consideration of damage to the carbon graphite thin film. The spot size is preferably 10 to 50 μm in consideration of cutting accuracy and positional accuracy of the ribbon-like carbon graphite thin film. In this way, after fixing the carbon graphite thin film to the frame substrate, laser processing is performed, and it is processed into a ribbon shape, thus simplifying the complicated process of accurately fixing the ribbon in the same interval and in parallel. In addition to being able to do this, the dimensional accuracy is also improved, which is an industrially very useful process.

  The capturing electrode 3 is fixed so that a capturing electrode 30 made of a carbon graphite thin film 310 can be electrically connected to a terminal of a printed wiring 33 provided on an insulating frame substrate 32. The carbon graphite thin film 310 is composed of a carbon graphite thin film made of the same material as the carbon graphite thin film 210.

  The frame substrate 32 of the capturing electrode 3 is provided with a window 320 for forming a charged particle beam passage space S3, and the carbon graphite thin film 310 constituting the trapping electrode 31 is printed wiring 33 so as to straddle the passage space S3. It is fixed between the connection terminals.

  The preferable range of the thickness, density, and graphite interlayer distance of the carbon graphite thin film 310 is the same as that of the carbon graphite 210 of the monitor electrode.

The distance between the monitor electrode 2 and the capture electrode 3 (the distance between the carbon graphite thin films) is preferably as wide as possible from the viewpoint of vacuum exhaust characteristics, and is wide from the viewpoint of electrical secondary electron capture. There is no need for too much. From these viewpoints, when the size of the frame substrate 31 is about 100 × 100 mm ² , 3 to 10 mm is preferable and 3 to 10 mm is more preferable. When the frame size of the frame substrate 31 is larger than this, it is preferable to further increase the interval by several mm. On the other hand, the interval does not change when the frame size of the frame substrate 31 is smaller than this.

  The material of the frame substrate 32 is not particularly limited as long as it has insulating properties, radiation resistance, and low gas emission characteristics in a vacuum. The frame substrate 32 can be made of the same material as the frame substrate 22 of the monitor electrode 2.

  The individual terminals for drawing out the printed wiring 33 are connected to the anode terminal (see FIG. 1) of the DC power supply 5 for voltage application. When the amount of secondary electron emission is high, a capacitor having a capacity of about μF may be inserted into the anode terminal.

  Next, a preferred embodiment of the quantum beam profile measurement method of the present invention will be described based on the measurement method using the beam monitor device.

  The beam monitor device 1 having the above-described configuration is set on the trajectory of the quantum beam to be measured in the particle accelerator, and a direct current power source is supplied to the capture electrode 31 of the capture electrode 3 so as to be more positive than the monitor target 21 of the monitor electrode 2. A voltage is applied by the device 5.

  In this state, the charged particles are incident on the monitor target 21, and the positive charge signal of each charge integrator 4 connected to the monitor electrode 2 is detected, so that the vertical beam profile of the incident charged particle beam is obtained. It can be measured. The energy of the charged particle beam whose profile can be measured by the beam monitor apparatus 1 of the present embodiment is several hundred keV or more, depending on the type of charged particle (the light energy such as electrons passes through the membrane even at about 1 keV). In principle, it can be measured.) However, considering the power of beam loss, it depends on the beam intensity. Highest possible energy is desirable, and 1 MeV or more per nucleon is desirable. In the beam monitor apparatus 1 of the present embodiment, even in the case of such a high-energy range and high-intensity charged particle beam, the beam loss can be suppressed low.

  As described above, the beam monitor device 1 according to the present embodiment includes the monitor electrode 2 including the monitor target 21 having excellent heat resistance, radiation resistance, and secondary electron emission characteristics. The vertical profile of an intense quantum beam can be measured with high sensitivity with low beam loss. In addition, since the capture electrode 3 has the same capture electrode as the monitor target of the monitor electrode 2, secondary electrons generated in the monitor target can be captured efficiently, and the monitor electrode 2 can be positively connected. Increased sensitivity in charge measurement

The present invention is not limited to the embodiment.
In the beam monitor device of the above embodiment, the monitoring electrode provided with the monitor target composed of the carbon graphite thin film arranged in parallel in the horizontal direction is used, but the direction in which the carbon graphite thin film is arranged in parallel with the profile to be measured. Can be set. In addition, by using a monitoring electrode including a monitor target in which carbon graphite thin films are arranged in parallel in different directions, beam profiles in different directions can be simultaneously measured.

  In the beam monitor apparatus of the present invention, the carbon graphite thin film is used for the capture electrode of the capture electrode as in the above embodiment, but a capture electrode that is conventionally used can also be used.

  Although the present invention is suitable for beam monitoring of charged particles as in the above-described embodiment, it can also be applied to monitoring devices for various quantum beams such as electromagnetic waves that interact with other films such as light. it can.

  The quantum beam monitor electrode of the present invention is suitable for a beam profile monitor as in the above embodiment, but other quantum beam monitor devices such as a beam intensity monitor (in this case, a capture electrode) It can also be used as an electrode for beam monitoring, such as monitoring of a loss beam deviating from the center of the beam course.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not restrict | limited to a present Example at all.

  The electrode for monitoring and the electrode for capturing were prepared as in the following examples and comparative examples, and a beam profile monitor device including those of the examples was prepared. The performance of the monitoring electrode was evaluated based on the beam loss, heat resistance, radiation resistance and detection efficiency. The results are shown in Table 1.

[Example 1]
<Production of carbon graphite thin film>
A polyimide film (manufactured by Ube Industries, Ltd., product name UPILEX 7.5SN, film thickness 7.5 μm) is sandwiched between air-permeable carbon sheets in a nitrogen gas stream at a rate of 10 ° C./min from 20 ° C. The temperature was raised to 1400 ° C. and held at 1400 ° C. for 120 minutes. The obtained carbonized film was laminated and set one by one with a breathable carbon sheet in a graphitization hot press capable of uniaxial pressing. Thereafter, the temperature was raised at a rate of 10 to 20 ° C./min in an argon gas atmosphere, maintained at 3000 ° C. under a pressure treatment condition of 3 MPa for 90 minutes, and then cooled in the furnace while gradually reducing the pressure. The appearance of the obtained carbon graphite thin film had a smooth and grayish luster. The carbon graphite thin film was not brittle and had flexibility. Further, the thickness of the carbon graphite thin film was 2.2 μm, and X-ray wide angle scattering was measured in the transmission and reflection modes. As a result, it was confirmed that the graphite crystals were oriented and grown in the direction of the thin film surface. The graphite interlayer distance was 0.3349 nm, and the crystallinity was 90% or more. Furthermore, according to the analysis of X-ray wide angle scattering, the crystallite size was 10 nm or more in both the a and c axis directions of the crystal.

<Monitor electrode>
The carbon graphite thin film produced as described above is vacuumed on a frame substrate (thickness 1.6 mm, width 199.5 × length 125 mm ² (window width 150 × length 80 mm ² )) on which printed wiring of silver-palladium alloy is applied. 30 pieces (30ch) ribbon-like form (length 92mm, width 1.5mm, form aligned in one direction with a distance of 1mm between adjacent films) by laser processing and fixing with conductive adhesive To obtain a monitor electrode. The laser processing was performed using an ultraviolet laser (spot size of about 10 μm) with a dimensional accuracy and a positional accuracy of ± 10 μm. The conductive adhesive for vacuum was used in a vacuum environment of 1 × 10 ⁻⁷ or less and with an adhesive and a use amount that do not deteriorate the vacuum environment.

<Capture electrode>
A carbon graphite thin film (thickness: 2.2 μm, width: 40 m, length: 92 mm, graphite interlayer distance: 0.3349 nm) made of the same material as that used for the monitor electrode is mounted on a frame substrate (thickness: 1.6 mm, width: 199.5 × length 125 mm ² (Madoyoko 150 × vertical 80 mm ²⁾⁾ in and secured with two gaps without conductive adhesive for the vacuum.

  A stainless steel 1.5 mm spacer was interposed on both sides of the obtained monitor electrode, and the distance between the carbon graphite thin film surfaces of the monitor electrode and the capture electrode was set to 3.1 mm.

[Comparative Example 1]
A monitor electrode having a tungsten wire with a thickness of 30 μm was used as a monitor target.

[Comparative Example 2]
A monitor electrode having an aluminum foil with a thickness of 5 μm was used as a monitor target.

[Comparative Example 3]
A monitor electrode provided with a titanium foil having a thickness of 5 μm was used as a monitor target.

[Evaluation of beam loss]
Since it is difficult to measure the beam loss directly and quantitatively, the trial calculation was evaluated by the following method.
Evaluation was made based on ΔE, which is an amount proportional to the energy loss obtained from the atomic number Z, mass number A, density ρ [g / cm ³ ] and thickness t [cm] of the material used for the monitor target. The difference in the lateral spread of the foil and the wire is 0.1 [cm] in the case of the foil, and the width W [cm] in the case of the wire having the same width as the wire diameter t [cm]. Evaluation was made by treating the multiplied product as ΔE. The results evaluated in the following four stages are shown in Table 1.
ΔE [g / cm] = ρ [g / cm ³ ] × Z / A × W [cm]
◎: Less than 1 × 10 ^-5 ○: 1 × 10 ^-5 or more Less than 1 × 10 ^-4 △: 1 × 10 ^-4 or more Less than 1 × 10 ^-3 ×: 1 × 10 ^-3 or more

[Evaluation of heat resistance]
The heat resistance of the material used for the monitor target was evaluated using the following four melting point values. The evaluation results are shown in Table 1.
◎: 3000 ° C or more ○: 2000 ° C or more to less than 3000 ° C △: 1000 ° C or more to less than 2000 ° C ×: 1000 ° C or less

[Evaluation of detection efficiency]
The detection efficiency of the monitoring electrode is considered as the total amount of secondary electron emission,
Total amount of secondary electron emission = P x [secondary electron emission rate of material] x [cross-sectional area of wire or foil]
Was estimated and evaluated. However, P is a proportionality constant. Although the total amount of secondary electron emission for each material has a gap of several times, it was clear that the difference in the cross-sectional area of the foil and the wire was dominant over the detected amount. It was evaluated in two stages. The results are shown in Table 1.

  As shown in Table 1, it was found that the monitor electrodes of the examples had low beam loss and were excellent in heat resistance, radiation resistance, and detection efficiency.

[Example 2]
The positive charge detected by the monitor electrode of the beam monitoring apparatus of the first embodiment is amplified by 400 times with a charge integrator, integrated with a time constant of 33 μm, and this is multiplexed and displayed on an oscilloscope. Attempt to monitor profile. An example of the oscilloscope display is shown in FIG. Thus, according to the beam monitor apparatus of Example 1, it turned out that the profiling of a proton beam can be measured with high sensitivity. From the profile of FIG. 3, it was found that the horizontal beam size was about 25 mm. Moreover, in the beam monitor apparatus of Example 1, even when 10 ²⁰ or more protons are irradiated with a 500 MeV proton beam in 10 months, no abnormality is observed in the waveform of the profile, and as a monitor over a long period of time. I found it to work.

[Comparative Example 4]
Using the monitoring electrode of Comparative Example 2, proton beam irradiation was performed under the same conditions as in Example 2. As a result, when the proton irradiation of the order of 10 ¹⁷ pieces was performed, the monitoring electrode was damaged and measurement was impossible.

  INDUSTRIAL APPLICABILITY The present invention is used for various types of quantum beam monitoring devices and quantum beam monitoring electrodes attached to a particle accelerator, an electromagnetic wave generating device that interacts with a carbon graphite thin film, which is used for medical use, industrial use, and the like. be able to.

It is a figure which shows typically one Embodiment of the quantum beam monitor apparatus of this invention. It is a perspective view which shows typically the arrangement state of the electrode for a monitor and the electrode for a capture | acquisition in the quantum beam monitor apparatus of this invention. It is a figure which shows the state which displayed the profile of the proton beam measured by the beam monitor apparatus of an Example on the oscilloscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Quantum beam monitoring apparatus 2 Electrode for quantum beam monitoring 21 Monitor target 210 Carbon graphite thin film 22 Frame substrate 23 Printed wiring 3 Secondary electron capture electrode 31 Capture electrode 310 Carbon graphite thin film 32 Frame substrate 33 Printed wiring 4 Charge integrator 5 DC Power supply

Claims (6)

  An electrode for quantum beam monitoring, comprising a monitor target in which a plurality of ribbon-like carbon graphite thin films are arranged in parallel along one direction at predetermined intervals.   2. The quantum beam according to claim 1, wherein the carbon graphite thin film has a thickness of 0.5 to 100 μm, a width of 0.05 to 50 mm, and a distance between adjacent carbon graphite thin films of 0.01 to 100 mm. Monitor electrode.   The electrode for quantum beam monitoring according to claim 1 or 2, wherein the carbon graphite thin film has a length of 5 to 300 mm. It is a manufacturing method of the electrode for quantum beam monitors according to any one of claims 1 to 3,
After fixing the carbon graphite thin film on the frame substrate having a quantum beam passage space so as to straddle the passage space, the carbon graphite thin film is irradiated with a laser beam, and the carbon graphite thin film is arranged along one direction at predetermined intervals. A method for manufacturing an electrode for quantum beam monitoring, wherein the monitor target is formed by processing into a plurality of ribbon-like forms arranged side by side.   The quantum beam monitor apparatus which comprises the electrode for quantum beam monitors of any one of Claims 1-3. A method of measuring a quantum beam profile using the quantum beam monitor device according to claim 5.

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