Heavy Ion Accelerator Research Articles

Influences of well contact on multiple-cell upsets in 28 nm SRAM

In order to study the effects of the feature size reduction and well contact placement on the characterization of topology patterns and the charge collection mechanism of device heavy ion single event multiple upset on a nanometer scale, the heavy ion single event effect experiment on the domestic 28 nm static random-access memory (SRAM) is carried out on the experimental platform of HI-13 heavy ion accelerator in Beijing. Based on the mapping relationship between the logical address and physical address of the device, the experimental data are processed, and the 28 nm SRAM heavy ion single event upset cross section curves, multiple upset percentage, and multiple upset topology patterns are obtained. The results are compared with those of heavy ion single event effect experiments in 65 nm SRAM, showing that under the influences of factors such as feature size reduction and lower operating voltage, the heavy ion single event upset threshold and the bit upset saturation cross section of 28 nm SRAM decrease significantly. In the direction perpendicular to the well, owing to the reduced 28 nm SRAM feature size, even if the single nucleon energy of the incident high LET (linear energy transfer) heavy ion is low, its deposited charge is sufficient to affect the three SRAM cells across the well direction due to the combined effect of ion track coverage, well potential modulation caused by the parasitic bipolar amplification effect and carrier diffusion, resulting in the fact that the 28 nm SRAM topology pattern has a shape of <i>n</i> rows × 3 columns, which poses new challenges and requirements for the anti-radiation hardened technology with scrubbing and EDAC (error detection and correction). Owing to the global well contact deployment, the charge deposited by the incident ions in the well far away from the well contact is difficult to discharge quickly, and the parasitic bipolar amplification effect lasts longer. The charge sharing competition between two p-channel metal oxide semiconductor in SRAM cell causes the single event upset recovery, which is the fundamental reason why the discontinuity of multiple upset topology pattern appears in 28 nm SRAM. This study provides a new anti-radiation hardened idea for suppressing the single event upset by using the parasitic bipolar amplification in the future.

Preparation of different carbon stripper foils and application in beam diagnostics

The production of carbon stripper foils that are mounted at different locations of the heavy-ion accelerator is an important task of the target laboratory, and the process for the preparation of carbon foils is constantly improved. Recently, we tested additional heat treatment of the carbon stripping foils following our standard procedure to reduce stress in the foils, since the performance and the durability of these stripping foils is a crucial factor for effective operation. We investigated the properties of foils produced some time ago and of foils freshly produced with the standard procedure, and foils treated thermally after the standard procedure. For the beam diagnostic department at GSI radiation resistant target materials for transverse ion beam profile measurement is an ongoing research topic. In that framework, the feasibility of Optical Transition Radiation (OTR) generation due to ion beam interaction with metal target for beam profile determination has been investigated. Here, carbon stripper foils are applied to enhance the OTR signal. The differently prepared foils were applied in many different experiments of the beam diagnostic department. We describe the performance of the foils during irradiation and compare the features of foils before and after irradiation.

The 300 MeV proton and heavy ion accelerator complex for SESRI project in China

The 300 MeV proton and heavy ion accelerator complex, which is the key part of SESRI (Space Environment Simulation and Research Infrastructure) project, is currently under construction in China. It comprises an 18 GHz high charge-state ion source, a 108.48 MHz cascaded linac injector consisting of a four-rod RFQ and three interdigital H-mode drift tube linacs, a compact synchrotron, and three irradiation terminals. The extensive ion species from proton to 209Bi32+ will be injected into the synchrotron using multi-turn injection method. The third-order resonance and RF-knockout extraction scheme is adopted to provide quasi-continuous spill for irradiation experiments. The general design of the accelerator complex and simulation results are discussed in this paper.

Creation, evolution, and future challenges of ion beam therapy from a medical physicist's viewpoint (part 1). Introduction and Chapter 1. accelerator and beam delivery system.

Radiation therapy for cancer using the Bragg peak of an ion beam has been making steady progress after being proposed by Robert Wilson in 1946. At the end of 2020, 12 dedicated treatment devices existed in operation worldwide, and approximately 40,000 patients have been treated with ion beams (mostly carbon ions). To date, ion beam therapy is superior to other treatments for rare cancers in the head and neck as well as bone and soft tissues; however, most recently, evidence submitted in Japan for the 2022 revision of public health insurance shows that ion beam therapy outperforms photon therapy for intractable common cancers such as pancreatic cancer and liver cancer. This may greatly expand its indications. Lawrence Berkeley Laboratory in the United States started research of ion beam therapy, National Institute of Radiological Sciences in Japan built the first dedicated device Heavy Ion Accelerator in Chiba and started systematic clinical research, and GSI in Germany developed the scanning irradiation method and rotating gantry for the first time. This paper presents the history and future challenges of ion beam therapy in three fields: accelerator and beam delivery system, physical/biological model and treatment planning system, and clinical research. This study is divided into three parts describing the achievements and roles of the three laboratories. In Part 1, accelerator and beam delivery system are described.

Design of plasma shutters for improved heavy ion acceleration by ultra-intense laser pulses

In this work, we investigate the application of the plasma shutters for heavy ion acceleration driven by a high-intensity laser pulse. We use particle-in-cell and hydrodynamic simulations. The laser pulse, transmitted through the opaque shutter, gains a steep-rising front and its peak intensity is locally increased at the cost of losing part of its energy. These effects have a direct influence on subsequent ion acceleration from the ultrathin target behind the shutter. In our 3D simulations of silicon nitride plasma shutter and a silver target, the maximal energy of high-Z ions increases significantly when the shutter is included for both linearly and circularly polarized laser pulses. Moreover, application of the plasma shutter for linearly polarized pulse results in focusing of ions toward the laser axis in the plane perpendicular to the laser polarization. The generated high energy ion beam has significantly lower divergence compared to the broad ion cloud, generated without the shutter. The effects of prepulses are also investigated assuming a double plasma shutter. The first shutter can withstand the assumed sub-ns prepulse (treatment of ns and ps prepulses by other techniques is assumed) and the pulse shaping occurs via interaction with the second shutter. On the basis of our theoretical findings, we formulated an approach toward designing a double plasma shutter for high-intensity and high-power laser pulses and built a prototype.

The role of collisional ionization in heavy ion acceleration by high intensity laser pulses

We present here simulation results of the laser-driven acceleration of gold ions using the EPOCH code. Recently, an experiment reported the acceleration of gold ions up to 7 MeV/nucleon with a strong dependency of the charge-state distribution on target thickness and the detection of the highest charge states {text {Z}} sim 72. Our simulations using a developmental branch of EPOCH (4.18-Ionization) show that collisional ionization is the most important cause of charge states beyond Z = 51 up to He-like Au.

Status of the SABRE South experiment at the Stawell underground physics laboratory

The SABRE (Sodium iodide with Active Background REjection) experiments aim to detect an annual rate modulation from dark matter interactions in ultra-high purity NaI(Tl) crystals. The SABRE South experiment is located at the Stawell Underground Physics Laboratory (SUPL), Australia, and is the first deep underground laboratory in the Southern Hemisphere. SABRE South is designed to disentangle seasonal or site-related effects from the dark matter-like modulated signal first observed by DAMA/LIBRA in the Northern Hemisphere using an active veto and muon detection system. It is a partner to the SABRE North effort at the Laboratori Nazionali del Gran Sasso (LNGS). SABRE South is instrumented with ultra-high purity NaI(Tl) crystals immersed in a linear alkyl benzene (LAB) based liquid scintillator veto, further surrounded by passive steel and polyethylene shielding and a plastic scintillator muon veto. Significant work has been undertaken to understand the experimental backgrounds and performance of the crystals. The SABRE South experiment is under construction, and will be commissioned from late 2022 to early 2023. We will present the final design of SABRE South, the status of its construction, its expected background, and its sensitivity to a DAMA/LIBRA like modulation. We will also present recent quenching factor measurements of sodium nuclear recoils in NaI(Tl) crystals measured at the Heavy Ion Accelerator Facility, and a report on the status of SUPL.

Eddy current and structural analysis of the beam pipe for the BRing dipole magnet

Fast-ramping magnets will be used in the Booster Ring (BRing) of the High-Intensity Heavy Ion Accelerator Facility (HIAF), which is proposed by the Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS). The dipole magnet will provide the field quality from the injection field of 0.0496 T up to the maximum value of 1.5786 T, with the maximum ramping rate of 12 T/s. The ramping magnetic field induces eddy currents that give rise to eddy loss and large force on the beam pipe, field delay and sextupole field appear to affect the field quality provided by the BRing dipole. An in-detail understanding of these effects is an essential aspect of the design. Based on the finite-element analysis, a simplified model by use uniform background magnetic field was used to the transient simulations, eddy current and the forces on the pipe at different times on the beam pipe were performed. This paper presents the results obtained for the eddy loss and magnetic field delay for different wall thicknesses. Then, mechanical design details are presented, and also stress distribution, the deformation in the beam pipe. The analysis results revealed that the eddy current and thus the field delay and eddy current-induced Lorentz force scales linearly with the derivative of the magnetic field and the thickness of the pipe. The power losses that cause heating of the pipe is linear with the square of the derivative of the magnetic field and the thickness of the pipe.

Research on the layout of primary control network and new measurement method for the HIAF survey and alignment

HIAF (High Intensity heavy ion Accelerator Facility) is one of the major national science and technology infrastructure projects in the “12th Five-Year Plan” undertaken by the Institute of Modern Physics, CAS. The primary control network, as the basic framework of the local coordinate system control of the particle accelerator, is the basis for calculating the coordinates in the process of accelerator construction and implementation, and plays a very important role in the survey and alignment during the construction period and the maintenance and monitoring during the operation period. Based on the multi-dissimilar design structure of HIAF and the unique geological conditions of the construction area, a new high-density layout method of the primary control network and a high-precision 3D(three-dimensional) measurement method were studied, and were successfully applied to the survey and alignment of HIAF. Inside and outside the accelerator tunnel, a high-density 3D primary control network that can form a full envelope for the accelerator beam is respectively laid out. All primary control networks are embedded in the bedrock layer with stainless steel reference inner cylinder and outer protective cylinder, and special waterproof filling layer is set up. All primary control network points in the accelerator tunnel are equipped with measuring intervisible holes and measurement platforms that can directly perform 3D measurements on the ground. By setting up the laser tracker on the horizontal attitude of the measurement platform, the 3D coordinates of the primary control network points inside and outside the accelerator tunnel can be measured directly and with high precision, and the simultaneous adjustment of the measurement data can be completed. The HIAF primary control network layout and measurement method proposed in this paper overcomes the problems of heavy pile foundation, poor crack resistance and poor water seepage resistance of the primary control network laid by the traditional method and solves the problem that the traditional primary control network must separate the plane network and the elevation network for independent measurement. The traditional method of tunnel point and forced centering measurement is avoided. By using a laser tracker to directly measure the 3D coordinates of the primary control network points inside and outside the tunnel, the measurement efficiency and measurement accuracy of the primary control network are improved, and the reliability of primary control network measurements is increased. The feasibility and correctness of the HIAF primary control network layout and measurement method are verified by comparing the actual multi-system measurement results in the field. This method has a certain reference value for the layout of the primary control network of the same type of accelerator.

Radiation shielding design for the target area in the pre-separator of HFRS at HIAF

High energy FRagment Separator (HFRS), an essential part of High Intensity heavy-ion Accelerator Facility (HIAF), is used to produce, separate and identify the Radioactive Ions Beams (RIBs). The target area in the pre-separator of HFRS can produce very strong secondary radiation, which seriously threatens the radiation safety of the environment, public and personnel. In this work, the FLUKA code is used to complete the radiation shielding calculation and design of the target area. Firstly, the secondary radiation produced by 25 different typical beam–target combinations are compared. The parameter of 78Kr in fast extraction mode is determined as the basis for the radiation shielding design based on its strongest secondary radiation. Then, the secondary neutron spectrum and the induced radioactivity of the production target and the beam dump are analyzed. The results show that the maximum neutron energy is close to 3 GeV, and special attention should be paid to high-energy neutrons in shielding design, as well as the maximum residual dose rates on the surface of the production target and the beam dump are 3.93 × 107μSv/h and 9.58 × 107μSv/h, respectively, after one month of continuous irradiation. Furthermore, the radiation shielding design is completed using the Q235 steel compact shielding together with the ordinary concrete and sand soil, based on the Monte Carlo simulations and the relevant dose limits. Finally, the radiation effects under this shielding scheme are analyzed. The results show that the shielding design meets the relevant design goals and can provide reliable radiation protection for the environment, public and personnel.

SPIRAL2 Cryomodule Models: A Gateway to Process Control and Machine Learning

From simple physical systems to full production lines, numerical models could be used to minimize downtime and to optimize performances. In this article, the system of interest is the SPIRAL2 heavy ion accelerator cryogenic system. This article illustrates three different applications based on a SPIRAL2 cryostat model: optimal controller synthesis, virtual sensor synthesis, and anomaly detection. The two first applications have been deployed on the system. Experimental results are used to illustrate the benefits of such applications. The third application is a case study based on data generated from a thermodynamic twin model.

DCT&CCT Superconducting Multiplets for HIAF-HFRS

HIAF (High Intensity heavy ion Accelerator Facility) is the new generation heavy ion accelerator under construction in China. The HFRS (FRagment Separator of HIAF) is a fragment separator and also a transfer-line between the Booster Ring and the Spectrometer ring, which has magnetic rigidity up to 25 Tm. HFRS magnet system is composed of 11 superconducting dipoles and 13 sets of triplets. Several multipole magnets (an octupole coil, a quadrupole coil, and a sextupole coil) are nested together to compact the length of the HFRS-line. All of them feature high field gradients (13 T/m, 25 T/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 105 T/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) and large bores (320 mm). To reduce the cold mass and ensure the field quality, the whole multipole magnets are all designed with coil-dominated magnets of CCT (Canted Cosine Theta) and DCT (Discrete Cosine Theta). This paper will introduce the general design process of an HFRS multipole module. The development process and test results of the prototype will be presented.

Electro-Thermal Coupling Model of Quench Protection With a Quench-Back for DCT&amp;CCT Superconducting Magnets

As promising magnet types, discrete-cosine-theta and canted-cosine-theta (DCT&CCT) superconducting magnets are designed for the High Energy Fragment Separator (HFRS), a fragment separator of the High Intensity Heavy Ion Accelerator Facility (HIAF). Quench protection is one of the key issues for DCT&CCT superconducting magnets due to low thermal conductivity between each turns and slow transverse quench propagation. Thermal quench-back induced by the center cooper wire as a heater automatically is a feasible quench protection option for the magnet wound with 6+1 type superconducting cables (six superconducting wires and one center cooper wire). In the present paper, an electro-thermal coupling model is developed and validated to deal with the dynamic coupling behaviors of electrical and temperature fields inside the superconducting magnets during quench protection process. The transient evolutions of current and voltage-to-ground are numerically obtained by finite element method, which shows obvious quench-back behaviors and agree well with the experimental measurements of the prototype magnet L800 in first round test. The hot-spot temperature can be reduced significantly considering quench-back effect. Furthermore, the quench protection baselines of temperature and quench integral are analyzed and predicted for L800, indicating that the magnet can be protected properly by the protection method with a quench-back at ultimate current 466A.

Design and Test of a Half-Aperture Canted-Cosine-Theta Multipole Prototype Magnet for the HIAF FRagment Separator

A novel Canted-Cosine-Theta (CCT) coil technology is first proposed and applied to the HIAF (High Intensity heavy-ion Accelerator Facility) FRagment Separator, which can offer an arbitrary multipole fields and meet the requirements of high magnetic stiffness (25 Tm). In this paper, a half-aperture CCT multipole prototype magnet was built and successfully tested by the Superconducting Magnet Group at Institute of Modern Physics (IMP). This magnet consists of four CCT formers that produces the gradients of 20 T/m@500 A and 120 T/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> @385 A, with a clear bore diameter of 200 mm.Two types of conductor placement methods are chosen and wound into the grooves of formers. The goal of the R&D of prototype is to verify the fabrication process, including coil winding, joints, assembly and impregnation. The detailed design and analysis for the half-aperture prototype magnet will be presented, along with results for the first stage of tests.

Superconducting Magnet Development for the HIAF Accelerator Complex

The High Intensity Heavy-ion Accelerator Facility (HIAF) is a new project under construction in China, which will provide beams of stable and unstable heavy ions with high energies, high intensities, and high quality. This paper discusses the superconducting magnet system for this accelerator complex. It will consist of a Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn magnet with the peak field of 12 Tesla for the ECR ion source operated at 45 GHz, 52 solenoids typically 676 mm long with an operating field of 7.5 Tesla for the superconducting Linac called iLinac, 11 superferric dipoles with 320 mm wide good field region, 13 coil-dominated multiplets with an aperture of 320 mm, gradient 13 T/m for the fragment separator HFRS. This paper reports the design and prototype development status of the main components.

The Study on the Quench Helium Release Process of HFRS Superconducting Magnet

The quench phenomenon of the accelerator superconducting magnet may occur in operation, which will cause the liquid helium in the cryostat to evaporate rapidly and release in the atmosphere. High-pressure helium will result in serious damage on significant components in the transmission line, and the released helium in the tunnel will lead to the ODH (Oxygen Deficiency Hazard), threatening the safety of operators. In this paper, the species transport model was used to study the 2D helium discharge process of fragmentation separator in HIAF (High-Intensity heavy-ion Accelerator Facility) by using the platform of computational fluid dynamics software FLUENT. To verify the effectiveness of the species transport model for the FLUENT in simulating the mixing jet process of different components, a 2D FLUENT simulation results of the LHC helium release process was compared with the experimental results and the 3D OpenFOAM simulation results. The results show that the species transport model based on FLUENT could predict the helium release process effectively. Then the distributions of helium concentration, temperature, and velocity in the HFRS (High energy FRagment Separator) tunnel were studied and obtained by the present work. Based on the above analysis, a reasonable design scheme of the accelerator superconducting magnet relief system can be accomplished for HFRS.

Research on automatic positioning technology for magnetic field measurement of multipole magnet harmonic coil in heavy ion accelerator

In the magnetic field measurement of accelerator magnets, efficient and accurate positioning of the magnetic field measurement system and the magnet is a critical process. By analyzing the mechanical structure and working principle of harmonic coil magnetic field measurement system, an automatic positioning technology is proposed in this research for the high-precision and fast positioning of multipole magnet and harmonic coil magnetic field measurement system. Through the special design and comprehensive application of multi-camera photogrammetry system, control system and six-degree-of-freedom (6DoF) attitude automatic adjustment system, fast non-contact measurement and automatic attitude adjustment of harmonic coil magnetic field measurement system and multipole magnet can be realized. The proposed automatic positioning system and operation scheme can not only save labor costs, but also improve the reliability of harmonic coils and the positioning efficiency of magnetic field measurement system. The proposed research can also monitor the position changes of the harmonic coil and the multipole magnet in the magnetic field measurement process in real time through the multi-camera photogrammetry system, and further control the accuracy of the magnetic field measurement of the harmonic coil.

A prototype of beam profile measurement system for HIAF-HFRS beam line

ABSTRACT A prototype of beam profile measurement system developed by the Institute of Modern Physics, which can work in the proportional region and ionization region, respectively, by adjusting the pressure and voltage, has been tested several times and achieved the design expectation. When the working pressure of the detector is low enough, the system can work in the secondary electron mode to measure the fast extraction beam profile too. The measurement system has been used to measure the profile of carbon ion beam in the Second Radioactive Ion Beam Line in Lanzhou in slow extraction mode and fast extraction mode, respectively. It is confirmed that the measurement system can measure the profile of carbon ion beam with a dynamic range of beam intensity up to six orders of magnitude. We used the X-ray beam to simulate the Gaussian-like distribution for laboratory testing, and the results show that the measurement system has a better resolution than 0.1 mm for the beam position with a Sigma of about 1.6 mm. This measurement system, together with the harps measurement system, will be able to meet needs of most beam profile measurements in High energy Fragment Separator (HFRS) at High Intensity heavy-ion Accelerator Facility (HIAF).

Design of a radio frequency quadrupole for a high intensity heavy-ion accelerator facility

We report a design work of a continuous-wave (cw) radio frequency quadrupole (RFQ) for the injector linac of the High Intensity heavy-ion Accelerator Facility project. The rf design and multiphysics analysis were conducted to enhance the long-term stability and reliability of the cavity. To minimize the peak modified Poynting vector and peak surface electric field associated with the rf breakdown rate, the cross section and the vanes segmentation of the RFQ cavity were optimized. Pi-mode stabilizing loops (PISLs) were adopted for the cavity to increase the mode separation between the quadrupole and the neighboring dipole modes, intending to reduce the emittance growth and beam loss caused by the field asymmetry of the quadrupole mode. Due to the lack of a universal criterion of acceptable mode separation, the field asymmetry of the quadrupole mode was directly used as the design criterion for the PISL. Tuners were designed to tune the cavity frequency and longitudinal field flatness. Thermal distributions on tuners with and without rf sealing were investigated, and we found that rf sealing was indispensable in decreasing the tuner's temperature. A multiphysics analysis was carried out to maintain the cavity frequency while running with different rf power, in an attempt to avoid frequently adjusting the cooling water temperature when accelerating different ions. The analysis also verified that a large wall thickness could make the cavity possess a low stress and a minor deformation.

Accelerator mass spectrometry measurements of 93Zr for astrophysical and nuclear technology applications

Zirconium-93 is a long-lived radionuclide with a half-life of (1.61 ± 0.05) × 106 yr. Production cross sections for 93Zr by neutron capture on stable 92Zr in the keV and thermal energy ranges are important input parameters for astrophysical network calculations and nuclear industry, respectively. Despite their importance, existing experimental data suffer from large uncertainties. Here, the combination of neutron activation and accelerator mass spectrometry (AMS) is presented as an alternative method to online time-of-flight measurements for the determination of these cross sections. The main challenges for AMS of 93Zr are the interference from the stable isobar 93Nb and the production of suitable reference material. At the Heavy Ion Accelerator Facility (HIAF) the first challenge is tackled with the available high particle energies and by investigating different Zr compounds and extracted molecular beams. Using ZrF5− beams extracted from ZrF4 sample material, it is shown that the Nb background can be reduced by up to two orders of magnitude relative to the extraction of ZrO− beams from ZrO2. Using the 13+ charge state and particle energies of ∼190 MeV, 93Zr/Zr background levels in the 10−12 range are regularly achieved at HIAF. The ZrF5− output from ZrF4 samples may be highly variable but can be stabilised using an intimate mixture of ZrF4 and PbF2 at a ratio of 1:10 that has been dried down from a concentrated hydrofluoric acid solution. An option to produce a well-characterised 93Zr reference material by utilising the well-known 235U-fission yield of 93Zr is discussed. Once this remaining challenge is resolved, accurate measurements of the astrophysically and technologically relevant neutron-capture cross sections of 92Zr using AMS will be possible at HIAF.