- Email: [email protected]
14 MeV high intensity cyclotrons: Two projects in progress
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
14 MeV high intensity cyclotrons: Two projects in progress a,⁎,1
a
a
a
a
a
Xianlu Jia , Tianjue Zhang , Guofang Song , Feng Wang , Fei Wang , Guang Yang , Jianjun Yanga, Richard R. Johnsonb, Pengzhan Lia, Shigang Houa, Gaofeng Pana, He Zhanga, Jingfeng Wanga a b
T
China Institute of Atomic Energy, Beijing, China University of British Columbia, Vancouver, BC, Canada
ARTICLE INFO
ABSTRACT
Keywords: Cyclotron PET CYCIAE-14
A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). In order to provide high quality proton beams for instant radiopharmaceutical distribution, and to produce a variety of radioactive ion beams taking use of the solid target, CYCIAE-14 adopts an injection system based on the external H- ion source, axial injection, and spiral inflector with a designed high beam intensity, while most PET cyclotrons adopt internal ion source. With the different using for the cyclotron, there are two projects. One project with 200 μA/14 MeV can be used for isotope production of 11C, 15O, 13N and 18F. Another project with more than 400 μA with 14 MeV can be used for more isotopes produced such as 64Cu, 124I and 99mTc. This paper will introduce the cyclotron of CYCIAE-14 with the two projects, and some experiments finished on the cyclotron will also be given in the paper, for example the 18F and 89Zr production, BNCT test.
1. Introductions A 10 MeV CRM cyclotron has been developed at China Institute of Atomic Energy (CIAE) with an achieved beam intensity of up to 430μA/ 1MeV [1]. Based on it, a 14 MeV high intensity compact cyclotron, CYCIAE-14, has been designed and built at CIAE [2–4]. CYCIAE-14 adopts an injection system based on the external H- ion source, axial injection, and spiral inflector with a designed beam intensity of higher than 400 μA, while the general PET cyclotrons adopt internal ion source providing 50–100 μA proton beams. To meet the needs of different user, the different ion source and injection line are used based on the CYCIAE-14, which bring two projects of the CYCIAE-14. One is a beam intensity of 200uA/14 MeV extracted from the cyclotron with a small multi-cusp H- ion source (CIAECH-I type) [5] and a short injection line, which can produced the usual isotope for PET 11C, 15O, 13N and 18F. Another is a beam intensity of more than 400uA/14 MeV was extracted from the cyclotron with a bigger multi-cusp H- ion source (CIAE-CH-II type) and a longer injection line, which can produced not only the usual isotope for PET, but also the isotopes such as 64Cu, 124I and 99mTc. The isotope 99mTc has wide
usage in the field of nuclear medicine, produced by the reaction (p, 2n)99mTc.
100
Mo
2. General description of the CYCIAE-14 The cyclotron consists 4 poles, a round return yoke, top and bottom yokes. To get strong vertical focusing, a 4-sector structure with variable hill gap is adopted with the fourth harmonic mode of operation for particle acceleration, which will also leave enough space to fix the cavities, and in the meanwhile effectively reducing the power supply. To achieve high intensity, CYCIAE-14 adopts an injection system based on the external H- ion source, axial injection, and spiral inflector with a designed beam intensity of higher than 400μA. A compact structue is adopted by CYCIAE-14, which use high magnetic field to decrease the size of magnet pole. The basic parameters of the cyclotron and the extract beam are tabulated in Table 1. 3. Injection line for two projects The cyclotron will be built to produce radioactive isotopes for PET diagnosis at the hospital. Therefore, it should follow three basic
Corresponding author. E-mail addresses: [email protected] (X. Jia), [email protected] (T. Zhang), [email protected] (G. Song), [email protected] (F. Wang), [email protected] (F. Wang), [email protected] (G. Yang), [email protected] (J. Yang), [email protected] (R.R. Johnson), [email protected] (P. Li), [email protected] (S. Hou), [email protected] (G. Pan), [email protected] (H. Zhang), [email protected] (J. Wang). 1 China Institute of Atomic Energy, Beijing 102413, China. ⁎
https://doi.org/10.1016/j.nimb.2020.01.009 Received 24 June 2019; Received in revised form 7 January 2020; Accepted 13 January 2020 Available online 23 January 2020 0168-583X/ © 2020 Elsevier B.V. All rights reserved.
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al.
Table 1 Basic parameters for the cyclotron and the extract beam. Maximum Beam Energy Radius of Magnet Poles Outer Radius of the Yoke Magnetic Field Frequency of RF system Accelerating Harmonics RF Resonators Ion Source Beam Injection Beam Extraction Accelerated/Extracted Beam Extracted Beam Energy Beam Intensity Beam Energy Dispersion On Target Beam Spot
Quantity Structure Dee Voltage Method Beam Line
14.6 MeV 0.50 m 0.88 m 2.0 kGs–18.5 kGs 73.02 MHz 4 2 λ/4 40 kV 5 mA Axial Injection Carbon Foil Striping 4 H−/H+ 14–14.6 MeV 400 μA ± 1.5% 8 × 8 mm
Fig. 2. Matching result for the injection line from the ion source extractor to the central region.
principles: (1) the entire system has high reliability; (2) it is easy to operate and control the machine; (3) the costs of constructing and running are economical; (4) the structure is to be sufficiently compact for the hospital environment. Given the H- beam will be provided by the external multi-cusp ion source, a low energy beam transport line is needed to inject the beam into the medium plane of the cyclotron. In our solution, the beam will be injected to the cyclotron axially by the injection line downwards to the spiral inflector which bends beam 90° onto the median plane of the central region.
The beam transport of d1-Q1-d2-Q2-d3-inf-CYCEN, where Q1 and Q2 are quadrupole, d1 and d2 are drift length, inf is the spiral inflector, and cycen is transport from inflector exit to central region matching. The two quadrupoles are placed in the pole of the main magnet. A beam intensity of 4 mA/25 keV from ion source is used to calculation. Fig. 2 shows the calculation result with 95% neutral beam. 3.2. Injection line of 400 μA There are the multi-cusp H- ion source (CIAE-CH-II type) and increase a buncher comparing with the injection line of 200μA. The ion source can supply the maximum of 10 mA H- beam. The layout of the injection line is shown in Fig. 3, which includes a multi-cusp ion source, a vacuum chamber, a Faraday cup, a collimator, a diaphragm, a vacuum valve and two molecular pumps. All of the elements are same except the buncher. The total length of this layout is 290 mm longer than the former one. In order to enable the switching between the two
3.1. Injection line of 200 μA The injection line is designed as short as possible. The total length from the outlet of ion source to the inflector should be less than 1.2 m, as shown in Fig. 1. Since the vacuum of the ion source extraction area is important, the vacuum box is designed as two parts, an ion source vacuum box and a beam diagnostic box. A 1300 L/s turbo-pump is used for vacuum box to improve the vacuum of the ion source. 700 L/s turbo-pump is used for diagnostic box and the injection pipe. A small multi-cusp H- ion source (CIAE-CH-I type) is used in the injection line, which can provide the maximum of 5 mA H− beam.
Fig. 1. The injection line of 200 μA.
Fig. 3. The injection line of 400 μA. 43
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al.
446Gauss. Since the diameter of the main magnet bore is only 120 mm and the fringe field is not negligible. Therefore, the doublet deserves careful treatment. In order to facilitate the manufacturing and installing, the two quadrupoles were designed to fix together and the shape of the pole was design as an arc curve, rather than the theoretical hyperbola curve. The crossing section of a 1/4 part of the quadrupole is shown in Fig. 6a, and the schematic of the setup structure for quadrupole is shown in Fig. 6b. To avoid the gases that leaking out of the coils, the coils as well as the poles and the return yoke of the quadrupole should locate outside of the vacuum. This idea can be achieved by designing a tray which is welded to the pipeline in the center and sealed to the cover plate of the main magnet at the larger radius with O ring for vacuum, Fig. 6b. The experiment shows the heat generated in the stuffed coil could not be transferred only with external assistant cooling, so the inner hollow wire wrapped by insulating lacquer is required to construct the coil. The crossing section is a ring with inner diameter of 2 mm and outer diameter of 3 mm. The water flowing in the hollow will be sufficient to transfer the heat. The pole and the return yoke should be manufactured separately, and they be fixed together after installing the coil onto the pole.
Fig. 4. The schematic of the layout of the injection line with the buncher.
solutions, the upper part of the injection line can be shifted on the axial direction less than 300 mm. To get better quality beam from the ion source, a collimator with diameter of 8 mm will be setup under the extraction pole of the ion source. In order to extract 400µA, the ion source will provide the 25 keV H− beam with a current of more than 4 mA. Therefore space charge effects will be significant and need to be compensated by charge neutralization. The neutralization of 95% is assumed in the design, which can be achieved with a vacuum of 10−4Pa. Fig. 4 shows the resulting beam profile given by optical design for the solution with buncher. The buncher will be set on the waist of beam, and the waist will be gotten by adjusting the parameter of the ion source. To get a better result, a solenoid has been prepared to be put before the buncher.
4. Local shielding To meet the space requirement for the cyclotron with local shielding, the injection line will be set under the cyclotron, and the local shielding will be installed around the cyclotron. The thickness of local shielding is calculated by the FLUKA code [6], with which get the dose rate distribution of the local shielding for the CYCIAE-14. Both photon and neutron dose rate are calculated by FLUKA. The radiation source term is 14 MeV/150μA proton hit thick water target by one of the extraction port. Neutron spectrum is shown in Fig. 7 and neutron yield is 3.9E-3n/p. The local shielding materials includes ordinary concrete, Boron doped concrete, Boron-containing polyethylene and lead. After design, all the shielding structure are composed with 60 cm ordinary concrete as main shielding wall and 80 cm local shielding including Boron doped concrete, Boron-containing polyethylene and lead. Outside the local shielding, photon is major external irradiation because concrete and PE are not for gamma ray shielding. The total dose rate out of the main shielding is lower than 1.5 μSv/h, the total dose rate distribution is shown in Fig. 8.
3.3. Buncher structure The structure of the buncher is illustrated in Fig. 5. The gap is 2.5 mm and the distance of D is 3/2βλ (the RF frequency is 73 MHz and the energy is 25 keV, so D = 45 mm). The radius of the inner wall is 20 mm and the effective buncher radius is 10 mm formed by eight tungsten wires with the diameter of 0.5 mm. The RF power of the buncher is obtained with a pick-up loop placed in the accelerating cavity of the cyclotron and fed to the middle electrode. The buncher voltage will be varied with an attenuator place between the pick-up and the buncher. The phase of the buncher with respect to the accelerating cavity will be adjusted by varying the cable length between the pick-up loop and the buncher.
5. Some experiments 5.1.
18
F isotope liquid target test
A smaller and easy operation liquid target has been designed at CIAE, which will be used for 18F isotope production. There are no valve on the beam pipe and no helium cooling system for the hava film of the target, which is different with the normal liquid target. The target only need one cooling water, which is enough for it, as shown in Fig. 9. The volume of the target is 2 ml, which got 1.5 Ci 18F ions on the CYCIAE-14 with 60 μA proton beam intensity for two hours. Since the material of the target is copper which only for experiment, so the yield is not well. The second target with seem structure and silver material is being done now, since the thermal conductivity is well and silver is not react with the 18F.
3.4. Quadrupole design In the beam optics design, a quadrupole doublet is used for transverse focusing. The maximum field on the surface of the pole is
5.2.
89
Zr production test
With the development of the biological macromolecules and Supramolecular System Markers in the PET isotopes, the labeled nuclides need matching the half life of the isotope. So, the 89Zr has been found for its important value. However, there is no 89Zr isotope could be supplied for study in China. Based on this, a simple solid target has
Fig. 5. The schematic of the buncher structure (unit: mm). 44
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al.
Fig. 6. (a) (left) The crossing section of the quadrupole, the inner and outer diameter of the coil are 2 and 3 respectively. (b) (right) Schematic of the setup structure.
Fig. 9. The being liquid target on the beam pipe.
Fig. 7. The Neutron spectrum for 14 MeV/150 μA proton on the water target.
widely accepted. However, this reaction has a lower yield comparing with the Be(p,n), which the reaction with 1.9 MeV proton about 2.4 × 10−6 (neutron/proton) [10,11]. The CYCIAE-14 is good for the Be(p,n) reaction, so some experiments has been done on it. A beryllium target with diameter of 10 cm and thickness of 6 mm is set at the end of the extraction beam pipe of the CYCIAE-14 with the proton of 40μA for an hour, and the 0°neutron yield is 5.5 × 10−3 (neutron/proton). With this experiment, some data for the BNCT were measured, such as neutron flux density. 6. Conclusions The cyclotron with short injection line has been finished, which can supply 200 μA proton beams through dual extraction with 4 beam lines. It is being installed in Beijing University of China, which will be used for some isotopes research including gas, liquid and solid target. The 400 μA cyclotron will be finished in next year, which plan to increase to 1 mA proton beam intensity at the cyclotron extraction target, and some experiments about BNCT will be done on it. Fig. 8. The total dose rate on the beam plane with CYCIAE-14 running.
Declaration of Competing Interest
been done, which has been used on the CYCIAE-14. 89Zr yield is about 4.5 mCi/(μA·h) on the 14 MeV cyclotron, with which some research results have been shown [7–9].
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
5.3. BNCT test
References
The common neutron-producing reaction 7Li(p,n)7Be at low proton energy for accelerator-based Boron Neutron Capture Therapy(BNCT) is
[1] Li Zhen-guo, et al., Atomic Energy Technol. 45 (5) (2011). [2] Tianjue Zhang, et al., Nucl. Instr. Methods Phys. Res. 269 (1) (2009) 79–85.
45
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al. [3] T. Zhang, et al., Nucl. Instr. Methods Phys. Res. B 269 (24) (2011) 2955–2958. [4] J.Q. Zhong, et al., Sci. China (Phys. Mech. Astronomy) 54 (2 Supplement) (2011) 266–270. [5] Zhang Tianjue, et al., Rev. Sci. Instrum. 85 (2014) 02B110. [6] A. Fasso, A. Ferrari, J. Ranft, et al., FLUKA: A multi-particle transport code. CERN2005-10 (2005), INFN /TC- 05/11, SLAC-R-773.
[7] [8] [9] [10] [11]
46
Y. Shi, et al., ACS Appl. Mater. Interfaces (2018). Dongban Duan, et al., ACS Appl. Mater. Interfaces 10 (49) (2018). Yaxin Shi, et al., Mol. Pharm. 15 (10) (2018) 4426–4433. Minoru Suzuki, et al., Radiother. Oncol. 92 (2009) 89–95. C.L. Lee, et al., Med. Phys. (2000) 192–202.
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
14 MeV high intensity cyclotrons: Two projects in progress a,⁎,1
a
a
a
a
a
Xianlu Jia , Tianjue Zhang , Guofang Song , Feng Wang , Fei Wang , Guang Yang , Jianjun Yanga, Richard R. Johnsonb, Pengzhan Lia, Shigang Houa, Gaofeng Pana, He Zhanga, Jingfeng Wanga a b
T
China Institute of Atomic Energy, Beijing, China University of British Columbia, Vancouver, BC, Canada
ARTICLE INFO
ABSTRACT
Keywords: Cyclotron PET CYCIAE-14
A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). In order to provide high quality proton beams for instant radiopharmaceutical distribution, and to produce a variety of radioactive ion beams taking use of the solid target, CYCIAE-14 adopts an injection system based on the external H- ion source, axial injection, and spiral inflector with a designed high beam intensity, while most PET cyclotrons adopt internal ion source. With the different using for the cyclotron, there are two projects. One project with 200 μA/14 MeV can be used for isotope production of 11C, 15O, 13N and 18F. Another project with more than 400 μA with 14 MeV can be used for more isotopes produced such as 64Cu, 124I and 99mTc. This paper will introduce the cyclotron of CYCIAE-14 with the two projects, and some experiments finished on the cyclotron will also be given in the paper, for example the 18F and 89Zr production, BNCT test.
1. Introductions A 10 MeV CRM cyclotron has been developed at China Institute of Atomic Energy (CIAE) with an achieved beam intensity of up to 430μA/ 1MeV [1]. Based on it, a 14 MeV high intensity compact cyclotron, CYCIAE-14, has been designed and built at CIAE [2–4]. CYCIAE-14 adopts an injection system based on the external H- ion source, axial injection, and spiral inflector with a designed beam intensity of higher than 400 μA, while the general PET cyclotrons adopt internal ion source providing 50–100 μA proton beams. To meet the needs of different user, the different ion source and injection line are used based on the CYCIAE-14, which bring two projects of the CYCIAE-14. One is a beam intensity of 200uA/14 MeV extracted from the cyclotron with a small multi-cusp H- ion source (CIAECH-I type) [5] and a short injection line, which can produced the usual isotope for PET 11C, 15O, 13N and 18F. Another is a beam intensity of more than 400uA/14 MeV was extracted from the cyclotron with a bigger multi-cusp H- ion source (CIAE-CH-II type) and a longer injection line, which can produced not only the usual isotope for PET, but also the isotopes such as 64Cu, 124I and 99mTc. The isotope 99mTc has wide
usage in the field of nuclear medicine, produced by the reaction (p, 2n)99mTc.
100
Mo
2. General description of the CYCIAE-14 The cyclotron consists 4 poles, a round return yoke, top and bottom yokes. To get strong vertical focusing, a 4-sector structure with variable hill gap is adopted with the fourth harmonic mode of operation for particle acceleration, which will also leave enough space to fix the cavities, and in the meanwhile effectively reducing the power supply. To achieve high intensity, CYCIAE-14 adopts an injection system based on the external H- ion source, axial injection, and spiral inflector with a designed beam intensity of higher than 400μA. A compact structue is adopted by CYCIAE-14, which use high magnetic field to decrease the size of magnet pole. The basic parameters of the cyclotron and the extract beam are tabulated in Table 1. 3. Injection line for two projects The cyclotron will be built to produce radioactive isotopes for PET diagnosis at the hospital. Therefore, it should follow three basic
Corresponding author. E-mail addresses: [email protected] (X. Jia), [email protected] (T. Zhang), [email protected] (G. Song), [email protected] (F. Wang), [email protected] (F. Wang), [email protected] (G. Yang), [email protected] (J. Yang), [email protected] (R.R. Johnson), [email protected] (P. Li), [email protected] (S. Hou), [email protected] (G. Pan), [email protected] (H. Zhang), [email protected] (J. Wang). 1 China Institute of Atomic Energy, Beijing 102413, China. ⁎
https://doi.org/10.1016/j.nimb.2020.01.009 Received 24 June 2019; Received in revised form 7 January 2020; Accepted 13 January 2020 Available online 23 January 2020 0168-583X/ © 2020 Elsevier B.V. All rights reserved.
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al.
Table 1 Basic parameters for the cyclotron and the extract beam. Maximum Beam Energy Radius of Magnet Poles Outer Radius of the Yoke Magnetic Field Frequency of RF system Accelerating Harmonics RF Resonators Ion Source Beam Injection Beam Extraction Accelerated/Extracted Beam Extracted Beam Energy Beam Intensity Beam Energy Dispersion On Target Beam Spot
Quantity Structure Dee Voltage Method Beam Line
14.6 MeV 0.50 m 0.88 m 2.0 kGs–18.5 kGs 73.02 MHz 4 2 λ/4 40 kV 5 mA Axial Injection Carbon Foil Striping 4 H−/H+ 14–14.6 MeV 400 μA ± 1.5% 8 × 8 mm
Fig. 2. Matching result for the injection line from the ion source extractor to the central region.
principles: (1) the entire system has high reliability; (2) it is easy to operate and control the machine; (3) the costs of constructing and running are economical; (4) the structure is to be sufficiently compact for the hospital environment. Given the H- beam will be provided by the external multi-cusp ion source, a low energy beam transport line is needed to inject the beam into the medium plane of the cyclotron. In our solution, the beam will be injected to the cyclotron axially by the injection line downwards to the spiral inflector which bends beam 90° onto the median plane of the central region.
The beam transport of d1-Q1-d2-Q2-d3-inf-CYCEN, where Q1 and Q2 are quadrupole, d1 and d2 are drift length, inf is the spiral inflector, and cycen is transport from inflector exit to central region matching. The two quadrupoles are placed in the pole of the main magnet. A beam intensity of 4 mA/25 keV from ion source is used to calculation. Fig. 2 shows the calculation result with 95% neutral beam. 3.2. Injection line of 400 μA There are the multi-cusp H- ion source (CIAE-CH-II type) and increase a buncher comparing with the injection line of 200μA. The ion source can supply the maximum of 10 mA H- beam. The layout of the injection line is shown in Fig. 3, which includes a multi-cusp ion source, a vacuum chamber, a Faraday cup, a collimator, a diaphragm, a vacuum valve and two molecular pumps. All of the elements are same except the buncher. The total length of this layout is 290 mm longer than the former one. In order to enable the switching between the two
3.1. Injection line of 200 μA The injection line is designed as short as possible. The total length from the outlet of ion source to the inflector should be less than 1.2 m, as shown in Fig. 1. Since the vacuum of the ion source extraction area is important, the vacuum box is designed as two parts, an ion source vacuum box and a beam diagnostic box. A 1300 L/s turbo-pump is used for vacuum box to improve the vacuum of the ion source. 700 L/s turbo-pump is used for diagnostic box and the injection pipe. A small multi-cusp H- ion source (CIAE-CH-I type) is used in the injection line, which can provide the maximum of 5 mA H− beam.
Fig. 1. The injection line of 200 μA.
Fig. 3. The injection line of 400 μA. 43
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al.
446Gauss. Since the diameter of the main magnet bore is only 120 mm and the fringe field is not negligible. Therefore, the doublet deserves careful treatment. In order to facilitate the manufacturing and installing, the two quadrupoles were designed to fix together and the shape of the pole was design as an arc curve, rather than the theoretical hyperbola curve. The crossing section of a 1/4 part of the quadrupole is shown in Fig. 6a, and the schematic of the setup structure for quadrupole is shown in Fig. 6b. To avoid the gases that leaking out of the coils, the coils as well as the poles and the return yoke of the quadrupole should locate outside of the vacuum. This idea can be achieved by designing a tray which is welded to the pipeline in the center and sealed to the cover plate of the main magnet at the larger radius with O ring for vacuum, Fig. 6b. The experiment shows the heat generated in the stuffed coil could not be transferred only with external assistant cooling, so the inner hollow wire wrapped by insulating lacquer is required to construct the coil. The crossing section is a ring with inner diameter of 2 mm and outer diameter of 3 mm. The water flowing in the hollow will be sufficient to transfer the heat. The pole and the return yoke should be manufactured separately, and they be fixed together after installing the coil onto the pole.
Fig. 4. The schematic of the layout of the injection line with the buncher.
solutions, the upper part of the injection line can be shifted on the axial direction less than 300 mm. To get better quality beam from the ion source, a collimator with diameter of 8 mm will be setup under the extraction pole of the ion source. In order to extract 400µA, the ion source will provide the 25 keV H− beam with a current of more than 4 mA. Therefore space charge effects will be significant and need to be compensated by charge neutralization. The neutralization of 95% is assumed in the design, which can be achieved with a vacuum of 10−4Pa. Fig. 4 shows the resulting beam profile given by optical design for the solution with buncher. The buncher will be set on the waist of beam, and the waist will be gotten by adjusting the parameter of the ion source. To get a better result, a solenoid has been prepared to be put before the buncher.
4. Local shielding To meet the space requirement for the cyclotron with local shielding, the injection line will be set under the cyclotron, and the local shielding will be installed around the cyclotron. The thickness of local shielding is calculated by the FLUKA code [6], with which get the dose rate distribution of the local shielding for the CYCIAE-14. Both photon and neutron dose rate are calculated by FLUKA. The radiation source term is 14 MeV/150μA proton hit thick water target by one of the extraction port. Neutron spectrum is shown in Fig. 7 and neutron yield is 3.9E-3n/p. The local shielding materials includes ordinary concrete, Boron doped concrete, Boron-containing polyethylene and lead. After design, all the shielding structure are composed with 60 cm ordinary concrete as main shielding wall and 80 cm local shielding including Boron doped concrete, Boron-containing polyethylene and lead. Outside the local shielding, photon is major external irradiation because concrete and PE are not for gamma ray shielding. The total dose rate out of the main shielding is lower than 1.5 μSv/h, the total dose rate distribution is shown in Fig. 8.
3.3. Buncher structure The structure of the buncher is illustrated in Fig. 5. The gap is 2.5 mm and the distance of D is 3/2βλ (the RF frequency is 73 MHz and the energy is 25 keV, so D = 45 mm). The radius of the inner wall is 20 mm and the effective buncher radius is 10 mm formed by eight tungsten wires with the diameter of 0.5 mm. The RF power of the buncher is obtained with a pick-up loop placed in the accelerating cavity of the cyclotron and fed to the middle electrode. The buncher voltage will be varied with an attenuator place between the pick-up and the buncher. The phase of the buncher with respect to the accelerating cavity will be adjusted by varying the cable length between the pick-up loop and the buncher.
5. Some experiments 5.1.
18
F isotope liquid target test
A smaller and easy operation liquid target has been designed at CIAE, which will be used for 18F isotope production. There are no valve on the beam pipe and no helium cooling system for the hava film of the target, which is different with the normal liquid target. The target only need one cooling water, which is enough for it, as shown in Fig. 9. The volume of the target is 2 ml, which got 1.5 Ci 18F ions on the CYCIAE-14 with 60 μA proton beam intensity for two hours. Since the material of the target is copper which only for experiment, so the yield is not well. The second target with seem structure and silver material is being done now, since the thermal conductivity is well and silver is not react with the 18F.
3.4. Quadrupole design In the beam optics design, a quadrupole doublet is used for transverse focusing. The maximum field on the surface of the pole is
5.2.
89
Zr production test
With the development of the biological macromolecules and Supramolecular System Markers in the PET isotopes, the labeled nuclides need matching the half life of the isotope. So, the 89Zr has been found for its important value. However, there is no 89Zr isotope could be supplied for study in China. Based on this, a simple solid target has
Fig. 5. The schematic of the buncher structure (unit: mm). 44
Nuclear Inst. and Methods in Physics Research B 466 (2020) 42–46
X. Jia, et al.
Fig. 6. (a) (left) The crossing section of the quadrupole, the inner and outer diameter of the coil are 2 and 3 respectively. (b) (right) Schematic of the setup structure.
Fig. 9. The being liquid target on the beam pipe.
Fig. 7. The Neutron spectrum for 14 MeV/150 μA proton on the water target.
widely accepted. However, this reaction has a lower yield comparing with the Be(p,n), which the reaction with 1.9 MeV proton about 2.4 × 10−6 (neutron/proton) [10,11]. The CYCIAE-14 is good for the Be(p,n) reaction, so some experiments has been done on it. A beryllium target with diameter of 10 cm and thickness of 6 mm is set at the end of the extraction beam pipe of the CYCIAE-14 with the proton of 40μA for an hour, and the 0°neutron yield is 5.5 × 10−3 (neutron/proton). With this experiment, some data for the BNCT were measured, such as neutron flux density. 6. Conclusions The cyclotron with short injection line has been finished, which can supply 200 μA proton beams through dual extraction with 4 beam lines. It is being installed in Beijing University of China, which will be used for some isotopes research including gas, liquid and solid target. The 400 μA cyclotron will be finished in next year, which plan to increase to 1 mA proton beam intensity at the cyclotron extraction target, and some experiments about BNCT will be done on it. Fig. 8. The total dose rate on the beam plane with CYCIAE-14 running.
Declaration of Competing Interest
been done, which has been used on the CYCIAE-14. 89Zr yield is about 4.5 mCi/(μA·h) on the 14 MeV cyclotron, with which some research results have been shown [7–9].
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
5.3. BNCT test
References
The common neutron-producing reaction 7Li(p,n)7Be at low proton energy for accelerator-based Boron Neutron Capture Therapy(BNCT) is
[1] Li Zhen-guo, et al., Atomic Energy Technol. 45 (5) (2011). [2] Tianjue Zhang, et al., Nucl. Instr. Methods Phys. Res. 269 (1) (2009) 79–85.
45
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