Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-04-25
Abstract： Abstract:
Objective: Cone beam CT（CBCT） can provide more accurate target location for patients during radiotherapy. However， due to the low contrast， loud noise and large artifacts caused by many scattered lines， the image quality is poor， and it cannot be used for dose calculation in real-time radiotherapy. This study aims to generate CBCt-based synthetic CT（sCTs） using three kinds of deep learning networks， namely Unet， CyclaGAN and CGAN， and study and compare the image quality of the three sCTs.
Methods: The CBCT and pCTs data of 78 patients with prostate cancer were preprocessed， including 63 training sets， 10 test sets， and 5 validation sets， to train and evaluate the image quality based on the three models， respectively. Image evaluation indexes such as mean absolute error （MAE）， mean error （ME）， mean square error （MSE）， peak signal-to-noise ratio （PSNR）， structural similarity （SSIM） and spatial non-uniformity （SNU） and frequency domain information were used for evaluation.
Results: Among the three models， CGAN model showed the best performance in each index. In terms of image quality under global conditions， the average MAE is reduced to 7.77HU， MSE is reduced to 4.99， PSNR is increased to 54.95， SSIM is increased to 96%.
Conclusion: The deep learning method can significantly modify the HU value of cbct and generate the corresponding high-quality sCT. For patients with prostate cancer， the sCT generated by cGAN has better image quality. The CBCt-based sCT generated by this model can provide the target dose calculation for prostate cancer radiotherapy.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-04-25
Abstract： [Background]: HVE-400 ion implanter is a kind of low energy accelerator as a special ion implantation equipment for semiconductor materials boron and phosphorus doping. The ion source and extraction deflection system are at high voltage platform, while the corresponding control system is at ground voltage position. The control signals and measurement signals of various parameters at the high-voltage end need to be transmitted between ground voltage and high voltage through optical fibers to isolate high voltage. After long time running, the fiber transmission control and monitoring system of the implanter can not work stably, an upgrade is required. [Purpose]: The wireless and digital transformation of the system is carried out, making it stable and easy to operate. [Methods]: Wireless transmission mode is used instead of fiber optic transmission, operating with high-voltage isolation. The transformation replaces the original distributed single-point control method with an advanced distributed centralized control method, and integrates all control and monitoring functions into an industrial control computer for digital operation and display. In the computer software, two kinds of automatic calculation of ion mass number are designed. [Results & Conclusions]: After the systerm updating, the graphical interface is simple and easy to configure and operate. The upgraded system has the characteristics of wireless, digital, centralized control, and simple operation.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-03-29
Abstract： [Background]: The neutron tube with a drive-in target has the advantages of high temperature resistance, stability, and long lifespan. It holds great potential for applications in the field of nuclear logging. [Purpose]: Research on simulating neutron yield from a neutron tube with a drive-in target can serve as a foundation for the physical design of such tubes. However, there is currently no numerical simulation tool available for simulating the desired reaction in a drive-in target neutron tube. [Methods]: Based on the TARGET program, an equivalent simulation method of T-D reaction is established by using the relationship between the integral neutron yield of D-T reaction and the integral neutron yield of T-D reaction under thick target condition. [Results]: Using this method, the effects of beam parameters and target parameters on neutron yield are calculated and analyzed. [Conclusions]: The results indicate that when the mixing ratio of D and T in the incident beam is 1:1, the neutron yield of the neutron tube with a drive-in target reaches its maximum value. Increasing or decreasing the proportion of D will result in a decrease in neutron yield. The parameters such as target atom ratio, beam energy, and single atom ion ratio are positively correlated with neutron yield. To enhance the neutron yield of a neutron tube with a drive-in target, it is advisable to maximize these parameters within the design constraints of the tube.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-03-25
Abstract： [Background]: Photonuclear reactions and compact neutron sources have emerged as promising tools for the production of medical isotopes, providing alternatives to conventional reactor-based high-enriched uranium methods. East China University of Technology (ECUT) is currently constructing an electron accelerator-driven photoneutron source(ECANS) for medical isotope production research. [Purpose]: Investigate the photonuclear reaction with 100Mo isotope and utilize the generated neutrons for isotopic production. [Methods]: The study involves analyzing the photonuclear reactions of 100Mo and investigating the neutron spectrum and activation yield of 99Mo within a high purity 100Mo target. Based on this photonuclear source, a new model to produce medical isotopes is established, comprising neutron energy modulation layer and neutron reflection layer. The study calculates the production yields of 99Mo, 177Lu, and 90Y in various natural oxides and assesses the feasibility of using photonuclear sources for medical isotope production. [Results]: The research results demonstrate that photo-nuclear reactions can effectively produce medical isotopes such as 99Mo, 177Lu, and 90Y, with respective activities of 17.4/day, 18.2 Ci/day, and 57.0 Ci/day. And in the high purity 100Mo target, the daily output of 99Mo reaches 54.1 Ci/day. [Conclusions]: The study demonstrates the feasibility of using the photodisintegration reaction of 100Mo as a neutron source for secondary production of medical isotopes. This approach offers the potential to enhance the economic viability of isotope production. The study analyzed the content of radioactive impurities in natural oxides under irradiation conditions, providing preliminary insights for subsequent separation and purification processes. Therefore, this research has certain reference value for the development of tools for radioactive isotope production.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-03-24
Abstract： X-band high-gradient linear accelerators are a challenging and attractive technology for compact electron linear-accelerator facilities. The Very Compact Inverse Compton Scattering Gamma-ray Source (VIGAS) program at Tsinghua University will utilize X-band high-gradient accelerating structures to boost the electron beam from 50 to 350 MeV over a short distance. A constant-impedance traveling-wave structure consisting of 72 cells working in the 2π/3 mode was designed and fabricated for this project. Precise tuning and detailed measurements were successfully applied to the structure. After 180 h of conditioning in the Tsinghua high-power test stand, the structure reached a target gradient of 80 MV/m. The breakdown rate versus gradient of this structure was measured and analyzed.
Peer Review Status:
Awaiting Review
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-03-19
Abstract： Superconducting synchrocyclotron has an ultra small structure, lower cost and is more suitable for use in proton therapy systems used in hospital environments. Compared with the current proton therapy system, the proton therapy system using the superconducting synchrocyclotron has a lower cost for single tumor treatment and has a huge application prospect, so it has been highly valued by many accelerator research and development institutions and enterprises. Regeneration extraction system is the key system of superconducting synchrocyclotron, and it is also the key and difficult point in the design of superconducting synchrocyclotron. In this paper, a regeneration extraction system was designed for a 230MeV proton superconducting synchrocyclotron for proton therapy. Because the regeneration extraction system is closely related to the main magnetic field, the design of the main magnet is carried out in the first part of this paper, and the related dynamic calculation results are given. The existing cyclotron design program does not have the design function of synchrocyclotron regenerative extraction system, so this paper develops a program that can design the regenerative extraction system. The design results show that the design of 230 MeV proton superconducting synchrocyclotron regeneration extraction system meets the extraction requirements, which can provide a reference for the design and engineering construction of other systems of superconducting synchrocyclotron.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-01-02
Abstract： The Shanghai high-repetition-rate X-ray free-electron laser and extreme light facility (SHINE) operates at a maximum repetition rate of 1 MHz. Kicker magnets are key components that distribute electron bunches into three different undulator lines in a bunch-by-bunch mode. The kicker field width must be less than the time interval between bunches. A lumped-inductance kicker prototype was developed using a vacuum chamber with a single-turn coil. The full magnetic-field strength was 0.005 T. This paper presents the requirements, design considerations, design parameters, magnetic field calculations, and measurements of the kicker magnets. The relevant experimental results are also presented. The pulse width of the magnetic field was approximately 600 ns, and the maximum operation repetition rate was 1 MHz. The developed kicker satisfies the requirements for the SHINE project. Finally, numerous recommendations for the future optimization of kicker magnets are provided.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-12-21
Abstract： The superconducting proton synchrotron is one of the most advanced domestically developed medical radiation therapy devices in China. As a crucial subsystem of the accelerator, the vacuum system provides the necessary operational environment for particle acceleration. This study aims to design the vacuum control system for the accelerator to maintain a stable high vacuum environment. Based on the vacuum design requirements of the accelerator, the design of the vacuum control system was accomplished using Siemens Programmable Logic Controller (PLC) hardware and the Experimental Physics and Industrial Control System (EPICS) software framework. The content includes the overall structure of the control system, system operational logic, user interface design, and safety interlocks. The results indicate that, during long-term operation, the system maintains a high vacuum level, and the control performance and stability meet the design requirements, ensuring the stable operation of the accelerator.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-12-14
Abstract： The space charge effect is the core problem of high intensity proton accelerator, especially at injection and initial acceleration stages. Using the phase space painting with optimized process, will effectively eliminate the influence of space charge effect on injection and acceleration efficiency, and emittance increase. Transverse phase space painting methods can be divided into correlated painting and anti-correlated painting. In this paper, firstly, the transverse phase space paintings for the high intensity proton synchrotron are discussed in detail, including different painting methods and different implementation methods. Secondly, based on the injection system of the China Spallation Neutron Source, the beam injection process and anti-correlated painting design scheme are studied in detail. The reasons for the reduction of the actual vertical painting range and the influence of edge focusing effects of the bump magnets on the painting and beam dynamics are deeply explored. In addition, the method to perform the correlated painting based on the mechanical structure of the anti-correlated painting scheme and its key role in realizing the CSNS design goal are briefly introduced. Finally, according to the requirement of switching between different painting methods online in future accelerators, a new injection scheme that can realize correlated and anti-correlated painting simultaneously has been proposed. The new painting injection scheme has been demonstrated, simulated and optimized in detail.
Subjects: Engineering and technical science >> Engineering Physics Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-12-13
Abstract： The China Spallation Neutron Source (CSNS) upgrade project (CSNS-II) aims to enhance the beam power from 100 to 500 kW. A dual-harmonic accelerating method has been adopted to alleviate the stronger space-charge effect in rapid-cycling synchrotrons owing to the increased beam intensity. To satisfy the requirements of dual-harmonic acceleration, a new radiofrequency (RF) system based on a magnetic alloy-loaded cavity is proposed . This paper presents design considerations and experimental results regarding the performance evaluation of the proposed RF system through high-power tests and beam commissioning. The test results demonstrate that the RF system satisfies the desired specifications and affords significant benefits for CSNS-II .
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-11-29
Abstract： The accelerator vacuum monitoring system is an important subsystem in the accelerator control system, which plays an important role in maintaining the normal operation of the accelerator. The design, development and development process of traditional large-scale control systems are highly dependent on physical entities, and the functional testing and performance verification of the whole system are all concentrated in the late stage of the project, resulting in a long development cycle of the control system, higher risks, and a tight time for late field debugging. To this end, industrial virtual debugging and virtual machine technologies were introduced to build a full-level virtual simulation debugging platform for the accelerator vacuum monitoring system. In the early stage of development, parallel collaborative development, full-level virtual debugging and logic rehearsal of the accelerator air monitoring system began to be carried out. Finally, the debugging results were applied to the site through on-site configuration, significantly shortening the time of on-site debugging. Reduce equipment loss and commissioning risk, improve project implementation efficiency and engineering design reliability.
Subjects: Nuclear Science and Technology >> Particle Accelerator Subjects: Electronics and Communication Technology >> Electron Technology submitted time 2023-11-29
Abstract： In light of the current international energy scarcity, nuclear power has emerged as a crucial source of clean energy. Proton accelerators have therefore become a pivotal technology in nuclear waste management. During beamline orbit correction processes, precise calculations of beamline orbit parameters are required. Given the demonstrated effectiveness of neural networks in a wide variety of industry domains, they offer promising potential for high-accuracy data fitting and prediction. Hence, this study proposes a novel direct linear accelerator beamline orbit parameter prediction technique based on edge intelligence computing nodes. This technique leverages BPNN to learn from historical data and generate a powerful model that can be seamlessly deployed to edge computing nodes, thereby accelerating the prediction of BPM location parameters. Furthermore, the proposed approach may be complemented by an adaptive compensation system in the future, which, in combination with edge computing nodes, could enable automatic beamline position correction, thereby achieving beamline orbit correction. Our experimental results demonstrate that FPGA, as an edge acceleration node, can achieve an inference speed of 2.5us, which represents a remarkable performance enhancement of approximately 165.6 times compared to CPU and approximately 7.9 times compared to GPU. The predicted results exhibit an average error of only 0.5%, and they exhibit the desired latency and accuracy characteristics.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-11-07
Abstract： EPICS, a software tool extensively used in large-scale scientific experiments such as particle accelerators. Depending on the scale of the facility, the number of EPICS PV can range from tens of thousands to millions. The ability to swiftly retrieve information related to EPICS PV can notably enhance the operational efficiency and maintenance of particle accelerators. To address this requirement, we designed and developed the EPICS PV information platform. This platform provides a unified user interface that supports the querying of PV lists, real-time statuses, historical data, put logs, IOC statuses, and IOC network information. It integrates these data points to offer a comprehensive view. The user interface of the platform leverages Web technology, with the server-side developed in the Node.js environment. This is complemented by software modules from the EPICS community. In addition, programs for network information collection and other cyclical executions are developed using the Python language. At present, the EPICS PV information platform has been successfully implemented in the CSNS accelerator, where it has significantly contributed to its effective operation and maintenance.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-08-21
Abstract： The purpose of this study was to design a rapid cycling synchrotron, making it capable of proton beam ultra-high dose rate irradiation, inspired by laser accelerators. The design had to be cheap and simple. We consider our design from six aspects: the lattice, injection, extraction, space charge effects, eddy current effects and energy switching. Efficiency and particle quantity must be addressed when injected. The space charge effects at the injection could affect particles’ number. The eddy current effects in the vacuum chambers would affect the magnetic field itself and generate heat, all of which need to be taken into account. Fast extraction can obtain 1010 protons/pulse, equal to instantaneous dose rate up to 107 Gy/s in a very short time, while changing various extraction energies rapidly and easily to various deposition depths. In the further research we expect to combine a delivery system with this accelerator to realize the FLASH irradiation.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-07-25
Abstract： Based on KONUS dynamics, the beam dynamic design of a compact IH-DTL with built-in permanent magnet quadrupole lens was completed. The DTL is comprised by 37 acceleration gaps and two sets of permanent magnet quadrupole lenses, which can accelerate C6+ ion beam of 20 emA from 0.5 MeV/u to 4 MeV/u. To control the transverse and longitudinal emittance growth of the low-energy heavy ion beams, the gap voltage, injection phase, magnet parameters, and energy and phase settings of the 0-degree reference particles have been optimized so that the transverse normalized RMS acceptance of the IH-DTL reaches 0.37π mm·mrad, and the transmission efficiency is above 95%.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-07-08
Abstract： Radio-frequency (RF) breakdown analysis and location are critical for successful development of high-gradient traveling-wave (TW) accelerators, especially those expected to generate high-intensity, high-power beams. Compared with commonly used schemes involving dedicated devices or complicated techniques, a convenient approach for breakdown locating based on transmission line (TL) theory offers advantages in the typical constant-gradient TW-accelerating structure. To deliver such an approach, an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fundamental theory of the TL transient response in the time domain. An equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit simulations. Furthermore, to validate the proposed fault-locating method in practical applications, an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and Technology. In addition, further considerations and discussion for extending the applications of the proposed method have been given. This breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supplement to existing methods, facilitating solution to construction problems at an affordable cost.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-25
Abstract： In this study, an X-band standing-wave biperiodic linear accelerator was developed for medical radiotherapy that can accelerate electrons to 9 MeV using a 2.4 MW klystron. The structure works at π/2 mode and adopts magnetic coupling between cavities, generating the appropriate adjacent mode separation of 10 MHz. The accelerator is less than 600 mm long and constitutes 4 bunching cells and 29 normal cells. Geometry optimizations, full-scale radiofrequency (RF) simulations, and beam dynamics calculations were performed. The accelerator was fabricated and examined using a low-power RF test. The cold test results showed a good agreement with the simulation and actual measurement results. In the high-power RF test, the output beam current, energy spectrum, capture ratio, and spot size at the accelerator exit were measured. With the input power of 2.4 MW, the pulse current was 100 mA and the output spot root-mean-square radius was approximately 0.5 mm. The output kinetic energy was 9.04 MeV with the spectral FWHM of 3.5%, demonstrating the good performance of this accelerator.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-20
Abstract： With the development of high-performance photon sources which have extremely low emittance,
autotuning magnet girders have drawn more and more attention, especially for diffraction-limited storage
rings and free-electron lasers. The biggest challenge is to simultaneously obtain high stability and high
flexibility. In this paper, an autotuning magnet-girder prototype has been designed and developed.
Topological optimization, multipoint supports, and locking systems have been applied for magnet-girder
design to improve the stability. The modal analysis accords with the vibration test well. The natural
frequency of the magnet-girder assembly is deduced as high as 45.6 Hz, which demonstrates good stability.
Ball-cam movers have been chosen as adjustment mechanisms, and a closed-loop control scheme has been
used to pursue high accuracy. The kinematic resolution is better than 1 μm, and the accuracy is better than
1 μm within the adjusting range of #1;5 mm. Besides, it can eliminate most of the calibration, which can
save much manpower and time. The tests demonstrate that the magnet girder can be used for beam-based
girder alignment with high stability and high accuracy.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
YANG Yao
YUAN You-Jin
FENG Yu-Chen
SUN Liang-Ting
FANG Xin
LU Wang
ZHANG Wen-Hui
CAO Yun
ZHANG Xue-Zhen
ZHAO Hong-Wei
Abstract： The operation of the HIRFL accelerator has shown that the beam transmission efficiency of the sector focusing cyclotron (SFC) injector line is rather poor. Beam simulations have been performed to investigate the possible causes for this low transmission. It is predicted that the property of transversal coupling of the ion beam from electron cyclotron resonance (ECR) ion source can be an important factor to degrade the beam quality by increasing the beam emittance, resulting in a serious particle loss. An improved operation scheme for the SECRAL associated line has been proposed, and the corresponding experiment was carried out. This paper presents the test results.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract： In this work, natural neutron spectra at nine sites in Tibet region were measured using a multi-sphere neutron spectrometer. The altitude-dependence of the spectra total fluence rate and ambient dose equivalent rate were analyzed. From the normalized natural neutron spectra at different altitudes, the spectrum fractions for neutrons of greater than 0.1 MeV do not differ obviously, while those of the thermal neutrons differ greatly from each other. The total fluence rate, effective dose rate and the ambient dose equivalent rate varied with the altitude according to an exponential law.
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