Proton Linear Accelerator Research Articles

Design and thermal-hydraulic analysis of multi-target system with 100 MeV proton linear accelerator for the production of 67Cu and 68Ge radioisotopes

Radioisotopes are widely used in the fields of medicine, science, and industry. The growing demand for medical radioisotopes has driven research on alternative production methods. In particular, both isotopes of 67Cu and 68Ge play vital roles in the medical environment in many countries to be used in the radio-immunotherapy and the positron emission tomography imaging, respectively. This study designed a multi-target system consisting of two Zn and one Ga2O3 plates to enable simultaneous production of the medical radioisotopes 67Cu and 68Ge using 100 MeV proton beams. To understand the thermal effect on the multi-targets, we examined the distribution of energy absorbed in each solid plate target when exposed to an accelerated proton beam through the thermal-fluid analysis based on ANSYS simulation. For confirming thermal stability for two Zn targets and one Ga2O3 target, the modified water flow path inside the multi-target system was designed effectively with the controlled distribution of multiple sub-holes between main inlet and the following four channels. It was confirmed that the newly designed multi-target system of Zn and Ga2O3 solid plates shows higher thermal stability than the case of uniform distribution of water inlet, which means it could be exposed to a higher current beam of 7.57% to decrease the processing time.

Operational Status and Future Plan of Proton Linear Accelerator at KOMAC

Since the second half of 2013, Korea Multi-purpose Accelerator Complex (KOMAC) has been supporting user beam service by using a 100-MeV proton linac and several beam line facilities. Proton beam service fields include various applications and research programs, such as material science, bio-medical science, semiconductor applications as well as nuclear physics and basic science. The 100-MeV linac is composed of an injector based on a 50-keV microwave ion source and two-solenoid LEBT (low energy beam transport), a 3-MeV RFQ with four-vane structure and conventional drift tube linac (DTL), where proton beam is accelerated from 3 MeV to 100 MeV. As the operation period of the proton accelerator exceeds 10 years and the cumulative operating time surpasses 30,000 hours, we judge that it is an opportune time to establish a long-term plan to prepare for the aging of the accelerator. To replace the currently operating RFQ, which shows degradation in performance (especially the beam transmission), we design a new RFQ with some modifications. For DTL, we are supposed to change the quadrupole magnet inside each drift tube from electromagnet type to permanent magnet type because the electromagnet has shown some trouble in view of long term stability. To leap forward in device and utilization technologies, we complete the construction of new facility of a Beam Test Stand (BTS) with a structure similar to the beam injection system (ion source, LEBT, RFQ) of the 100 MeV linear accelerator. We plan to actively conduct beam physics and accelerator research using this facility. Moreover, we are supposed to upgrade the proton linac to 1 GeV for spallation neutron source applications, which will be a long-term plan. In short term, we take phased approach with focusing the first phase at 200 MeV energy upgrade.

Preliminary studies of the MINERVA cryogenic supply system

MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) will be composed of a 600 MeV LINear ACcelerator (LINAC) with a large number of cryomodules and a 100 MW thermal power subcritical nuclear reactor cooled by lead-bismuth. The MINERVA MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility) project is the first phase of the MYRRHA project composed of a 100 MeV, 4 mA continuous-wave proton LINAC. The MINERVA LINAC takes advantage of 60 superconducting radiofrequency (RF) cavities cooled at 2 K by saturated superfluid helium (He II). The MINERVA cryoplant will supply the required cryogenic cooling power of the LINAC through cryogenic lines and cryogenic valve boxes. This paper describes the LINAC cryogenic system supply architecture, the different operating modes, the heat loads, the cryoplant main requirements and the strategy to comply with high reliability requirements. The MINERVA cryoplant shall provide helium flows at 40 K for the thermal shielding, at 5 K for the cooling of the RF couplers and at 2 K for the 60 superconducting cavities installed in 30 cryomodules. The total equivalent refrigeration power of the MINERVA cryoplant is about 3.5 kW at 4.5 K. The cryoplant is composed of a warm compression station including sub-atmospheric volumetric compressors, helium gas storages and a refrigeration cold box with cold centrifugal compressors.

Wide-aperture Faraday Cup for the High-Intensity Linear Proton Accelerator of the Project DARIA

One of the main problems for beam diagnostics in the projected linear proton accelerator for the DARIA compact neutron source is the high pulse and average beam power combined with a relatively low energy, that significantly limits the choice of possible diagnostic instruments and methods. For basic beam current measurements and tuning procedures in the low-energy part of the accelerator, a wide-aperture water-cooled Faraday cup was developed. This paper presents design features, estimations of thermal loads during typical operation and experimental results of the cup tests at a high-intensity proton beam, also the design features of such devices are described, considering the influence of the beam space charge on the measurement results.

Comparing the effects of irradiation with protons or photons on neonatal mouse brain: Apoptosis, oncogenesis and hippocampal alterations

Background and PurposeMedulloblastoma (MB) is a common primary brain cancer in children. Proton therapy in pediatric MB is intensively studied and widely adopted. Compared to photon, proton radiations offer potential for reduced toxicity due to the characteristic Bragg Peak at the end of their path in tissue. The aim of this study was to compare the effects of irradiation with the same dose of protons or photons in Patched1 heterozygous knockout mice, a murine model predisposed to cancer and non-cancer radiogenic pathologies, including MB and lens opacity. Materials and MethodsTOP-IMPLART is a pulsed linear proton accelerator for proton therapy applications. We compared the long-term health effects of 3 Gy of protons or photons in neonatal mice exposed at postnatal day 2, during a peculiarly susceptible developmental phase of the cerebellum, lens, and hippocampus, to genotoxic stress. ResultsExperimental testing of the 5 mm Spread-Out Bragg Peak (SOBP) proton beam, through evaluation of apoptotic response, confirmed that both cerebellum and hippocampus were within the SOBP irradiation field. While no differences in MB induction were observed after irradiation with protons or photons, lens opacity examination confirmed sparing of the lens after proton exposure. Marked differences in expression of neurogenesis-related genes and in neuroinflammation, but not in hippocampal neurogenesis, were observed after irradiation of wild-type mice with both radiation types.Conclusion.In-vivo experiments with radiosensitive mouse models improve our mechanistic understanding of the dependence of brain damage on radiation quality, thus having important implications in translational research.

Stereotactic radiosurgery for vestibular schwannomas: evolution of the philosophy of treatment

Vestibular schwannomas are the most common tumors in the cerebellopontine angle. Stereotactic radiosurgery is included in the armamentarium of methods for treating these tumors along with surgical treatment. Given the annual incidence of more than 15 radiosurgical cases of vestibular schwannomas per 1 million population, the expected need for stereotactic radiosurgery of these tumors in Russia is more than 2000 cases annually.Stereotactic radiosurgery is located at the intersection of several clinical specialties: neuroradiology, neurosurgery and radiation therapy, each of which has made a significant contribution to the development of this treatment method. The most commonly used for this is the cobalt‑based Leksell Gamma Knife, specifically intended for the treatment of intracranial neoplasms. Treatment is also possible with modern linear accelerators and proton accelerators, which provide high accuracy and conformity of irradiation. The experience gained since the first application of this method in the treatment of vestibular schwannomas has made it possible not only to optimize the radiation doses to the tumor and adjacent critical structures (brain stem, inner ear), but also to study the features of post‑radiation micro‑ and macro‑ changes, their impact on the clinical course, to develop recommendations for radiosurgery with schwannomas of various sizes. All this contributes to high control of tumor growth and a low level of functional disorders, which, along with easy tolerability and minimal hospitalization time, determines lower cost of this treatment compared to the traditional surgical approach and significant social and economic effect.This lecture is intended for neurosurgeons and radiation therapists and focuses on the most significant factors that influenced the development, promotion and active use of stereotactic radiosurgery of vestibular schwannomas in cli nical practice.

Investigation of random beam trips in a linear accelerator at the Japan proton accelerator research complex for the development of an accelerator-driven nuclear transmutation system

ABSTRACT In a proton linear accelerator (linac), the proton beam is sometimes unexpectedly interrupted because of the electrical discharge caused by radio frequency, device/equipment failure, and other factors. Are these beam trips random? Traditionally, beam trips have been implicitly assumed to occur randomly. In this study, we investigated whether beam trips occur randomly in the Japan Proton Accelerator Research Complex (J-PARC) linac. The aim was to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained by the Kaplan – Meier estimation, a reliability engineering method. This reliability function was used to investigate the randomness of beam trips. Analysis of operational data for five subsystems of the J-PARC linac for five years showed that beam trips occurred randomly in some subsystems. However, the beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, which are the primary subsystems of the proton linac.

Handling the Functional Features of Accelerator Components Using ISO GPS Situation Features

The building blocks of a scientific facility based on particle beams comprise magnets and electro-magnetic devices. The optical design usually imposes a demanding accuracy with respect to their theoretically exact position and orientation. It happens that the functional features are either not clearly defined – what is the « axis » of a magnet –, or not explicitly used along their lifecycle. Improving how to handle these functional features would contribute to meeting demanding challenges. The European Spallation Source (ESS) is aiming at providing a powerful proton linear accelerator and a target system to produce pulsed neutrons. The challenging complex design and integration yielded to introducing a tool shared in common by all stakeholders along the lifecycle: the “situation features”, as defined in ISO GPS (Geometrical Product Specifications) standards. They are here developed, and extended to beyond-mechanics use cases. Two examples of fiducialization and installation phases are presented for neutron beam guides and quadrupole magnets. Perspectives of generic use are also highlighted.

CONCEPTUAL DESIGN OF A RADIATION-FREE 800 MeV PROTON LINAC

Presented is the concept of a 800 MeV proton linear accelerator as a result of long-term research in ion linacs based on alternating-phase focusing (APF) in H-mode structures. Particle motion stability in the medium energy range of 5…100 MeV where the space charge effects are essential and main radiation losses occur, is provided by a combination of modified APF and magnetic focusing. This combined focusing technique can effectively prevent emittance growth and minimize radiation losses.

Contributions of MYRRHA to the European Fusion Energy Roadmap

One of the main objectives of the EUROfusion Roadmap to Fusion Energy during Horizon Europe is to finalize the conceptual design (thus preparing the engineering design phase) and initiate the construction of a fusion spectrum neutron source (IFMIF-DONES). The Belgian Nuclear Research Center is currently developing the MYRRHA research facilities, which include a subcritical accelerator-driven system ignited by a 600 MeV superconducting linear proton accelerator coupled to a 100 MeV proton injector. The implementation of the multipurpose fast spectrum reactor MYRRHA will proceed in phases, with phase I, covering 2019–2027, including the deployment of the 100 MeV proton accelerator and associated fusion material research facilities. The research on fusion materials on the basis of the 100 MeV proton beam and with hot cell facilities will focus on innovative materials and composites and will be fully complementary to IFMIF-DONES as well to the planned research program on using currently available nuclearized facilities such as BR2 (Belgian Research Reactor 2) and Hot Cells for mechanical, microstructural and chemical analysis. A bespoke fusion irradiation module is also foreseen on the MYRRHA reactor, the construction of which is planned in the third phase of the implementation of the project (i.e. after 2035). Provisions have been made in the core of the MYRRHA reactor to include so-called In-Pile Sections around the central core or at the central core position below the spallation target when operating in subcritical mode. In this contribution, we review the role and technical capabilities that MYRRHA facilities may provide in the framework of the European Fusion Electricity Roadmap and specifically for DEMO Engineering Design, Material's Development and enhancement of Technology Readiness Level. Aspects of education and training, being an integral part of the European nuclear fusion program, are also touched upon. Finally, the synchronization of the timelines for the implementation of MYRRHA and the EU fusion facilities are discussed.

Cryogenic distribution system design for cryomodules and cavities test in HIAF project

ABSTRACT High-intensity heavy-ion accelerator facility (HIAF) is an accelerator-driven high-current heavy ion facility, currently under construction in Guangdong, China. The proton linear accelerator of HIAF linac has 96 superconducting cavities and 17 cryomodules cooled by 2 K saturated superfluid helium. Cryogenic tests should be carried out in a test cryogenic system prior to the online operation of each cavity and cryomodule. The cryogenic distribution system (CDS) is the main part of the test cryogenic system, which is used for transporting cryogenic fluid between helium refrigerator and test terminals. A specific CDS is developed due to the long cryogenic test time. Each test terminal can be independently cooled and heated up, saving quite a bit of time without impacting the others. This article provides comprehensive explanations for the process design, process analysis, and special structure design which enhance the system’s maintainability. Furthermore, particular technical designs, such as measuring system, helium guard, and elimination of thermoacoustic oscillations, are described in detail.

Neutron facilities of the compact neutron source DARIA: parameters and features

The compact neutron source DARIA based on a linear proton accelerator is designed to create neutron beams for a diffractometer, a reflectometer, and a small-angle scattering setup. The experimental setups are optimized in terms of the range of momentum transfer, instrumental resolution, geometric dimensions, as well as in terms of the repetition rate and duration of neutron pulses.

Example Radiation Oncology Policy for Managing Patients With Implanted Electronic Devices Other Than Implantable Cardiac Pacemakers or Defibrillators

This article describes a community-based hospital's policy for the management of patients with medical implanted electronic devices other than pacemakers or implanted cardiac defibrillators (ICDs). The policy may be adapted as needed for other radiation oncology groups requiring a practical solution for managing the care of patients with implanted devices, noting the need for changes for departments offering proton, neutron, heavy ion, or magnetic resonance-guided linear accelerator (MR-linac) treatment modalities. The policy was developed using a risk-based approach, with each patient's risk level determined based on the patient's dependence on the device, the anticipated dose to the device, and the type of treatment used. A similar approach is used for patients with pacemakers or ICDs, but this policy was designed to accommodate patients with other types of devices with care managed outside the department. Such devices include, but are not limited to, hepatic pumps, intrathecal pain pumps, neurostimulators, cochlear implants, and loop recorders. The resulting definitions, guidelines, and proposed workflow were presented at the institution's multidisciplinary radiation oncology quality assurance committee monthly meeting and adopted as department policy in 2022. Recommendations incorporated in the policy include levels of patient monitoring and timing of device interrogation to minimize the risk of device malfunction. The policy was written to guide the management of treatment of patients with a range of medical implanted electronic devices. This policy is currently in operation at a community-based hospital.

DYNAMION—A Powerful Beam Dynamics Software Package for the Development of Ion Linear Accelerators and Decelerators

Numerous ambitious particle accelerator facilities, based on proton and ion linear accelerators, have recently been in development for fundamental research, as well as for industrial applications. The advanced design of such new machines, as well as the upgrade and optimization of existing linacs, requires adequate, precise and reliable tools to simulate beam dynamics. The software package DYNAMION, created about 30 years ago, is undergoing systematic improvement and further development in order to characterize modern ion linacs and to provide solutions for its intrinsic complex problems. The DYNAMION code features Front to End beam dynamics simulations under space charge conditions in a linac system, comprising an arbitrary sequence of accelerating-focusing structures and beam transport lines. The evolution of a macroparticle ensemble could be analyzed at a high level of specification. A 3D distribution of the external electrical field (RFQ, DTL) is modeled using integrated internal solvers. Optionally, a 3D electromagnetic field mapping, supplied by specialized external codes, could be used. The recent status of the DYNAMION software package is presented in this paper. Furthermore, the performance of the code is demonstrated on the basis of its application for various linear accelerator/decelerator projects.

Concept of Beam Instrumentation System for High-Intensity DARIA Proton Linac

Beam diagnostics is one of the main tasks during operation of charged particle accelerators. The paper presents a concept of a beam instrumentation system that provides diagnostic procedures and allows to measure and adjust the clue beam parameters in a linear resonant proton accelerator of a compact neutron source DARIA: current, position, profile, emittance, energy, phase characteristics. An important requirement is to provide measurements during the accelerator tuning procedure, when the beam parameters can be changed in a wide range. It is proposed to include in the main structure of the system such types of diagnostic devices as beam current transformers, stripline beam position monitors, wire scanners, ionization beam cross-section monitor, slit emittance meter, bunch shape monitor, water-cooled Faraday cup. A particular attention is paid to a non-destructive method due to a high pulse and average beam intensity in conjunction with a relatively low beam energy to provide continuous operational control of the beam parameters. Main physical principles of operation, typical characteristics, as well as features of the practical implementation of the devices are included. A possible arrangement layout of diagnostic units along the accelerator is proposed, taking into account peculiarities of using the proposed types of detectors in various parts of the accelerator.

Design of the Prototype of the Radio Frequency Quadrupole Sections for the Compact Neutron Source DARIA

The DARIA compact neutron source project based on a linear resonant proton accelerator is aimed at creating a serial facility capable of providing the Russian scientific community with pulsed neutron beams with intensities comparable to those of research nuclear reactors. The absence of fissile material makes it possible to significantly reduce the radiation safety requirements for such installations and, consequently, to place them at the site of leading scientific centers and universities that train specialists in the field of neutron physics. Under a grant from the Ministry of Science and Higher Education, key elements of the facility are being developed. The design and sequence of manufacturing for a full-scale model of an accelerator section with radio frequency quadrupole focusing and a resonator with drift tube linac are presented.

Hybrid Quadrupole Lens for the Focusing Channel of the DARIA Complex

The results of synthesis and electromagnetic calculation of a hybrid quadrupole lens for a proton linear accelerator of a compact neutron source DARIA are presented. The lens includes a permanent magnet quadrupole with a fixed magnetic field gradient and an auxiliary electromagnetic quadrupole excited by a pulsed current. The permanent magnet quadrupole is made of radiation-resistant rare-earth magnet, and the electromagnetic quadrupole is designed to compensate for permanent magnet magnetization losses resulting from radiation degradation as neutron fluence accumulates during accelerator operation. A hybrid quadrupole lens can be applied for fast adjustment of the focusing channel when accelerating ion beams with different ion mass-to-charge ratios.

The design of the ESS neutrino Super Beam ESS[formula omitted]SB for leptonic CP violating measurement and the plans for its further development ESS[formula omitted]SB+

A EC-supported conceptual design study ESSνSB has been carried out during the years 2018–2022 of how the 5 MW linear proton accelerator of the European Spallation Source, currently under construction in Lund, Sweden, can be used to generate a world-uniquely intense neutrino Super Beam for precision measurement of the leptonic CP violating phase δCP. Support for a continuation of this study 2023–2026 has recently been granted by EC. The uniquely high power of the ESS proton linac will allow for the neutrino oscillation measurements to be made at the second oscillation maximum, rather than at the first maximum where other experiments measure, and thereby for a more precise measurement to be made of δCP. This paper describes the results of the conceptual design of ESSνSB lay-out, infrastructure and components as well as of the evaluation of the physics performance for leptonic CP violation discovery and, in particular, for the precision in the measurement if the CP violation phase δCP as well as the plans for the continuation of the work, which will include design studies of a Low energy nuSTORM and an Low Energy Monitored Neutrino Beam.

Fusion-dedicated material irradiation facilities at MYRRHA: Conceptual design and damage equivalence studies

The Belgian Nuclear Research Centre is currently developing MYRRHA - a subcritical accelerator driven system ignited by a 600 MeV superconducting linear proton accelerator, cooled with an eutectic lead bismuth. The implementation of MYRRHA will take place in phases, where phase I, covering 2019–2027, includes the deployment of the 100 MeV proton accelerator and beam-added research facilities. Development of the dedicated facilities to enable irradiation of fusion materials and components is in the portfolio of this R&D block. The baseline concept of the 100 MeV fusion-dedicated facilities has been presented for the first time in 2019 and in this contribution, we extend its description and provide main elements of the conceptual design of the irradiation installations, preliminary configuration of the hot cell facilities (required to load/unload the irradiation modules), information on the irradiation envelope. In addition, we summarize the results of the computational study performed to investigate the equivalence (in terms of damage rate, nuclear transmutation, temperatures and expected irradiation-induced microstructure) of the irradiation conditions at MYRRHA facilities in comparison with other material test facilities such as IFMIF and ESS, and in DEMO as well as in the mixed-spectrum material test reactors. The aspects related to miniaturization of the sample geometries are also discussed to substantiate the feasibility and relevance of this facility for fusion material's R&D programme.

Non-destructive measurement of the beryllium thickness of the iBNCT neutron-generation target using negative muons

Accelerator-based boron neutron capture therapy (BNCT) has recently been studied by several researchers. In BNCT, a neutron-generation target is an important component because an intense neutron flux of more than 109n/cm2/s is required to complete medical treatments within an acceptable treatment time. In the Ibaraki BNCT (iBNCT) project, a proton linear accelerator (linac) consisting of a 3-MeV radio-frequency quadrupole and an 8-MeV drift-tube linac based on J-PARC linac techniques was used. As for the neutron-generation target, beryllium was adopted with an incident proton energy of 8 MeV. The target has a three-layer structure fabricated using hot-isostatic pressing (HIP). The first layer consists of 0.5 mm-thick beryllium, which is slightly shorter than the 8-MeV proton range in beryllium for neutron generation. The second is a 0.5 mm-thick palladium, which was selected owing to its durability against blistering, and the third is a 10 mm-thick copper for heat removal purposes with cooling water circulation. The thickness of the beryllium is very important because a shortage of thickness reduces the yield of neutrons, while an excess of thickness results in damage by stopped protons owing to a blistering effect. Despite its importance, this thickness has not yet been confirmed because it is not realistic to measure it destructively in terms of the construction cost of the iBNCT target; thus, a non-destructive measurement is desirable. This paper describes a method for measuring the thickness of the beryllium layer of a mockup of an iBNCT neutron target, which was constructed in the same way as the actual iBNCT, in a non-destructive manner using negative muon X-rays. The experiment was performed in the J-PARC MLF muon facility, and the obtained thickness was 0.48 ± 0.02 mm, which corresponds to the designed value of 0.50 ± 0.05 mm.