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The PREF project (Proton Radiation Effects Facility) aims to provide low to medium energy protons from 10–60 MeV, which is an excellent range for experimental research on the displacement damage effect studies of satellites and payload components, and is currently under construction in China. Average proton beam fluxes range from tens of particles/( cm 2 s) up to approximately 1 0 8 particles/( cm 2 s), spot sizes after scanning range from 2 × 2 cm 2 to 20 × 20 cm 2 , and uniformity is better than 95%. It comprises a 2.45 GHz ion source, a 325 MHz four-vane RFQ linac injector, a compact synchrotron, and two irradiation terminals. Protons will be injected into synchrotron using multi-turn injection scheme to obtain high-gain beam accumulation. The third-order resonance slow extraction scheme is adopted to achieve high efficiency and continuous uniform extraction of the beam for irradiation experiments. Several innovative accelerator technologies such as titanium alloy lined thin-wall vacuum chamber and fast ramping rate full energy storage power supply are also adopted. In this paper, the general design and simulation results of the accelerator complex are presented, and the new technology and progress of the PREF project are briefly introduced. [ABSTRACT FROM AUTHOR]

Abstract Heavy ion medical machine (HIMM) is the first Chinese heavy ion accelerator facility developed for cancer therapy. After commissioning, the slow extraction efficiency reached nearly 90% for all energies from 120 to 400 MeV/u. The spill duty factor exceeded 90% at a sample rate of 10 kHz. This paper reports the results of the HIMM's slow extraction commissioning. [ABSTRACT FROM AUTHOR]

Abstract The Isochronous Mass Spectrometry (IMS) based on storage rings is a powerful technique for mass measurement of short-lived exotic nuclei. The transition energy γ t of the storage ring is a vital parameter of the IMS technique. It is difficult to measure the γ t and its relation to momentum spread or circulating length, especially to monitor the variation of γ t during experiments. An experimental investigation on the γ t has been performed for the IMS experiment at the Cooler Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL-CSRe). With the velocity measured by two time-of-flight (TOF) detectors, the γ t as a function of orbital length can be determined. The influences of higher order magnetic field components on the γ t function were inferred for isochronous correction. This paper introduces and investigates the influence of dipole magnetic fields, quadrupole magnetic fields and sextupole magnetic fields on the γ t function. With the quadrupole magnets and sextupole magnets corrections, a mass resolution of 171332 (FWHM) and σ (T) ∕ T = 1. 34 × 1 0 − 6 were reached, which shall be compared with 31319 (FWHM) and σ (T) ∕ T = 7. 35 × 1 0 − 6 obtained without correction. [ABSTRACT FROM AUTHOR]

The Spectrometer Ring (SRing) is an essential part of the High Intensity heavy-ion Accelerator Facility project (HIAF) in China. It is designed as a multi-functional experimental storage ring, which will be able to operate in three ion optical operation modes. The SRing will be used as a time-of-flight mass spectrometer for short-lived, especially neutron-rich nuclei. It will also be used to collect and cool Rare Isotope Beams (RIBs) or highly-charged stable ion beams for nuclear and atomic physics experiments. The design magnetic rigidity is in the range 1.5 to 15 Tm. The beam cooling system consists of stochastic cooling and electron cooling devices. With a help of an electron cooler, stored ions will be decelerated to a minimum energy of 30 MeV/u by RF cavities. The extraction system of the SRing will allow cooled ion beams to be extracted to an external target for further ion manipulations or reaction experiments. The general ion optics design and technical requirements of SRing subsystems are presented and discussed in this paper. [ABSTRACT FROM AUTHOR]

To simulate collective instabilities during the complicated beam manipulation in the BRing (Booster Ring) of HIAF (High Intensity heavy-ion Accelerator Facility) or other high intensity accelerators, a code, named CISP (Simulation Platform for Collective Instabilities), is designed and constructed in China’s IMP (Institute of Modern Physics). The CISP is a scalable multi-macroparticle simulation platform that can perform longitudinal and transverse tracking when chromaticity, space charge effect, nonlinear magnets and wakes are included. And due to its well object-oriented design, the CISP is also a basic platform used to develop many other applications (like feedback). Several simulations, completed by the CISP in this paper, agree with analytical results very well, which shows that the CISP is fully functional now and it is a powerful platform for the further collective instability research in the BRing or other accelerators. In the future, the CISP can also be extended easily into a physics control system for HIAF or other facilities. [ABSTRACT FROM AUTHOR]

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 209Bi 32 + 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. [ABSTRACT FROM AUTHOR]

The High Intensity heavy ion Accelerator Facility (HIAF) is a new accelerator complex under design at the Institute of Modern Physics (IMP). The facility is aiming at the production of high intensity heavy ion beams for a wide range of experiments in high energy density physics, nuclear physics, atomic physics and other applications. It consists of a superconducting electron-cyclotron-resonance ion source and an intense proton ion source, a linear accelerator, a 34 Tm booster synchrotron ring, a 43 Tm multifunction compression synchrotron ring, a 13 Tm high precision spectrometer ring and several experimental terminals. A magnetized electron cooling device is supposed to be used in the booster ring for decreasing the transverse emittance of injected beams. The conceptual design and main parameters of this cooler are presented in this paper. [ABSTRACT FROM AUTHOR]

Abstract: HIMM, a new compact accelerator facility dedicated to carbon cancer therapy, has been designed and is presently under construction. The synchrotron has a compact structure that exhibits a circumference of only 56.2m. The charge exchange injection (CEI) method is adopted for synchrotron injection with a carbon-ion energy of 7MeV/u. The third-order resonance and RF-Knock Out scheme are adopted in this machine. The general design of the machine and injection/extraction simulation results is discussed in this paper. [Copyright &y& Elsevier]

In this paper the closed orbit correction of the Heavy Ion Medical Machine (HIMM) synchrotron is described. Results of simulations and measurements are presented. Consistently with simulations, it is possible to correct the maximum closed orbit distortion of the HIMM synchrotron down to 2.4mm in the horizontal direction and 0.7mm in the vertical one. The errors of dipole magnets, especially the longitudinal alignment errors (Δ s), have large impact on the horizontal correction results. A Singular Value Decomposition (SVD) algorithm is adopted for computing the correction. The residual orbits and the effects of reducing the number of singular values are analytically expressed and simulated. In addition, the influences of BPM reading errors as well as corrector setting errors are analyzed. For further optimization, the method to estimate the dipole errors is studied. In the commissioning, the maximum closed orbits at BPMs can also be well corrected to within 1mm through SVD algorithm. [ABSTRACT FROM AUTHOR]

Abstract The dynamic vacuum effect induced by the charge exchange beam loss will seriously limit the ion intensity and beam lifetime in the Booster Ring (BRing) of the High-Intensity Heavy Ion Accelerator Facility (HIAF). A dedicated collimation system has been designed to decrease the ion-induced gas desorption to suppress the dynamic vacuum effect. In order to reach 100% collimation efficiency, the optics lattice of BRing has been changed from original FODO to DBA structure. The distance between dipole and quadrupole in each lattice cell of BRing was optimized to maintain the high collimation efficiency. The hardware structure of the collimator was designed based on the simulation result and mechanical instrument control principle in the UHV vacuum system. The vacuum chamber and pump installment with collimators has been designed. A prototype collimator with vacuum chamber has been installed on the beamline to measure the gas desorption with beam and verify the availability and reliability of mechanical design. This prototype collimator has passed factory field tests and used to measure the gas desorption rate with the beam 112Sn 26 + at the energy 150 MeV/u successfully. [ABSTRACT FROM AUTHOR]

Heavy ion beam lost on the accelerator vacuum wall will release quantity of gas molecules and make the vacuum system deteriorate seriously. This phenomenon is called dynamic vacuum effect, observed at CERN, GSI and BNL, leading to the decrease of beam lifetime when increasing beam intensity. Heavy ion-induced gas desorption, which results in dynamic vacuum effect, becomes one of the most important problems for future accelerators proposed to operate with intermediate charge state beams. In order to investigate the mechanism of this effect and find the solution method for the IMP future project High Intensity heavy-ion Accelerator Facility (HIAF), which is designed to extract 1 × 1 0 11 uranium particles with intermediate charge state per cycle, two dedicated experiment setups have been installed at the beam line of the CSR and the 320 kV HV platform respectively. Recently, experiment was performed at the 320 kV HV platform to study effective gas desorption with oxygen-free copper target irradiated with continuous Xe 10 + beam and O + beam in low energy regime. Gas desorption yield in this energy regime was calculated and the link between gas desorption and electronic energy loss in Cu target was proved. These results will be used to support simulations about dynamic vacuum effect and optimizations about efficiency of collimators to be installed in the HIAF main synchrotron BRing, and will also provide guidance for future gas desorption measurements in high energy regime. [ABSTRACT FROM AUTHOR]

HIAF-BRing, a new multipurpose accelerator facility of the High Intensity heavy-ion Accelerator Facility project, requires an extremely high vacuum lower than 10 −11 mbar to fulfill the requirements of radioactive beam physics and high energy density physics. To achieve the required process pressure, the bench-marked codes of VAKTRAK and Molflow+ are used to simulate the pressure profiles of the BRing system. In order to ensure the accuracy of the implementation of VAKTRAK, the computational results are verified by measured pressure data and compared with a new simulation code BOLIDE on the current synchrotron CSRm. Since the verification of VAKTRAK has been done, the pressure profiles of the BRing are calculated with different parameters such as conductance, out-gassing rates and pumping speeds. According to the computational results, the optimal parameters are selected to achieve the required pressure for the BRing. [ABSTRACT FROM AUTHOR]

Abstract: HIRFL-CSR is a new ion cooler-storage ring system in China''s Institute of Modern Physics (IMP). This facility can accelerate all ions from protons up to the heaviest element, uranium, with variable energies for nuclear physics experiments, material irradiation research, and heavy ion particle therapy and so on. With the completion of this project, a new accelerator control system has been developed to accomplish the beam injection, accumulation, acceleration, extraction and manipulation. In this paper, the architectures of the HIRFL-CSR control system and timing system, the basic function of operation software, the data cycles of power supplies and the RF cavity are described in detail. Furthermore, to fulfill the requirements of special physics experiments and enhance the facility reliability, several operation software improvements, including eliminating the magnetic hysteresis effects, dipole magnets field slow feedback and super-period slow extraction, are also introduced in this paper. [Copyright &y& Elsevier]

Cooling efficiency in electron cooling systems is closely related to the velocity of electron. The velocity of electron has offset due to the space charge of the intense electron beam in the drift tube of the cooling section and thus increases the temperature of electrons. In order to minimize this effect, a new type of electron gun is adopted to produce a hollow electron beam in HIRFL-CSR e-cooler project. The hot ion beam is cooled by Coulomb interaction with intense and cold hollow electron beams. Using typical parameters of the CSRm e-cooler, theoretical calculations comparing the impact of the space charge field on electron velocity for solid and hollow electron beam are carried out. [Copyright &y& Elsevier]

As many diverse accelerator facilities are designed, constructed and operated by IMP (Institute of Modern Physics, Chinese Academy of Sciences), the existing physics control system cannot cover all requirements of these facilities. In order to save the construction time, improve the commissioning efficiency, simplify the operation and reach higher beam intensity and better beam quality, a new physics control system, PACS (Physics-oriented Accelerator Control System), is proposed, designed and implemented in the IMP. With the control layer in three layers, i.e. application layer, physics layer and control layer, the PACS is protocol neutral and can be deployed to all accelerator facilities in the IMP without massive reprogramming. The physics layer encapsulates all physics control processes, including device-level physics and system-level physics, into highly usable interfaces, which makes the development of the application layer and the customized applications simpler, more robust and efficient. Due to the OOP (Object-oriented Programming) technology used in this layer and specific designs, the PACS is highly scalable and can keep pace with the rapidly changing hardware and software. As the application layer is built upon the physics layer interfaces, no matter what is updated in the physics layer, the applications remain unchanged. Many new physics control processes can be tested and implemented in the physics layer by the developers or the users without influencing the operation of these facilities. Now, a version of PACS for miniature facilities is implemented and tested in the CSR, a heavy ion accelerator facility for scientific research in the IMP. It meets the expected goals and provides a solid base for following versions. In the future, the PACS will become a general-purpose physics control system for all heavy ion accelerator facilities. [ABSTRACT FROM AUTHOR]

BRing is the booster ring of the HIAF project in which the beam intensity is designed up to 1.0 × 1011 ppp (238U34+). In order to reach the required intensities, an efficient injection scheme is crucial and the beam loss during injection must not exceed the limits defined by machine protection and dynamic vacuum requirements. An injection scheme called two-plane painting multiturn injection is consequently proposed, which exploits both the horizontal and vertical acceptance of the BRing by a tilted electrostatic septum. The influence of the space charge on the injection process is important for the two-plane multiturn injection scheme which should provide the required intensity with a minimal beam loss. The impact of the space charge on the efficiency of the injection process is investigated using a modified ORBIT code. In order to achieve lower beam loss, the particle swarm algorithm is proposed for a detailed injection optimization with space charge effect. Detailed studies on the two-plane painting multiturn injection scheme and the dependence on the lattice tune, the injected beam current, and the injected beam emittance are also presented. The results provide an important guideline for the design optimization of the injection system for the HIAF-BRing. [ABSTRACT FROM AUTHOR]

Abstract The longitudinal dynamics of electron-cooled and radio-frequency (RF)-bunched 12 C 6 + and 16 O 8 + ion beams have been investigated at a heavy-ion experimental cooler storage ring CSRe. An rf-buncher was employed to longitudinally modulate the ion beams. A new resonant Schottky pick-up was applied to monitor the intensities and longitudinal dynamics of stored and electron-cooled ion beams. Using electron-cooling, the separated Schottky noise signals of the 12 C 6 + and 16 O 8 + ions were clearly observed in the Schottky spectrum. The storage times and the particle numbers of both ion beams were measured by Schottky noise, which demonstrated the ability to perform Schottky mass spectrometry measurements and also the measurement of highly charged ions at the CSRe. In addition, an enhancement of the Schottky noise signals was observed for rf-bunched ion beams, which could be used to diagnose the intensity ion beams at storage rings. Finally, a broadly longitudinal manipulation of the ion beams by scanning the bunching frequency was realized. The investigation of electron–ion recombination experiment at ultra-low collision energies by scanning the bunching frequency of the ion beams at the storage ring CSRe is proposed. Highlights • The individual lifetimes and numbers of the 12 C 6 + and 16 O 8 + ions were measured. • An enhancement of the Schottky noise signals was observed for rf-bunched ion beams. • A broadly longitudinal manipulation of the ion beams was realized. [ABSTRACT FROM AUTHOR]

All operational electron cooling systems employ a DC electron beam that generated by an electrostatic electron gun. This paper is devoted to the simulation of the electron cooling process with a pulsed electron beam, in which the electron cooling, Intra Beam Scattering and the space-charge field of the pulsed electron beam are included. A simulation of coasting ion beam cooling with a pulsed electron beam showed that the ion beam is cooled down to a small momentum spread, and all ions are captured by the bucket created by the pulsed electron beam space-charge field simultaneously. Finally, a cold pulsed ion beam with length the same as the electron pulse is obtained. In this article, the structure of the particle tracking simulation code is described and the simulation results of coasting and bunched ion beam cooling with a pulsed electron beam are presented and analyzed. Moreover, the preliminary experiment on CSRm is introduced and the result shows an agreement with the simulation. [ABSTRACT FROM AUTHOR]

The precise calibration of angular distribution of heavy-ion elastic scattering induced by Radioactive Ion Beams (RIBs) at energies around Coulomb barrier on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL) is presented. The beam profile and the scattering angles on the target are deduced by a measurement with two Multi Wire Proportional Chambers (MWPC), and four sets of detector telescopes (including Double-sided Silicon Strip Detectors (DSSD) placed systematically along the beam line, incorporating with Monte Carlo simulation. The MWPCs were used to determine the beam trajectory before the target, and the energies and the positions of scattered particles on the detectors were measured by the DSSDs. Minor corrections on the beam spot and the detector position are performed by assuming the pure Rutherford scattering at angles which are smaller than the related grazing angle. This method is applied for the elastic scattering of 17 F on 89 Y target at E lab =59 MeV and 50 MeV. [ABSTRACT FROM AUTHOR]

A significant deceleration effect on a stored coasting ion beam by a continuous-wave laser light was observed in the Schottky-noise spectrum during the laser experiments with lithium-like oxygen ion beams stored at a relativistic energy of 275.7 MeV/u at the heavy-ion storage ring CSRe in Lanzhou, China. The observed deceleration range of the laser (Δ p / p ≈ 5. 7 × 1 0 − 6 ) is much broader than the expected capture range (Δ p / p ≈ 3. 6 × 1 0 − 8 ), as calculated from the natural linewidth of the O 5 + ion's electronic transition (2 S 1 / 2 − 2 P 1 / 2). In order to explain this huge deviation, a phase space tracking code has been developed to investigate the interaction between the stored coasting ion beam and the laser light. Simulations reveal that the deceleration range of the typically narrow CW laser force is highly enlarged by taking into account the transverse betatron oscillation of the ions with larger emittance and the angular misalignment of the laser light direction. The experimental observation is well described by the systematic simulations. The present work is crucial for forthcoming laser cooling and precision laser spectroscopy experiments and simulations on heavy highly charged ions at the CSRe and the future facility HIAF. [ABSTRACT FROM AUTHOR]

At the heavy ion storage ring HIRFL-CSRe an electron cooler is operated to improve the beam conditions for experiments. The properties of cooled beams have been studied. The longitudinal beam dynamics during the cooling process was measured by a resonant Schottky detector. The dependencies of the parameters electron beam density and profile on cooling times were investigated. The friction force was measured directly with the aid of the high voltage system of the cooler and with the application of the beam bunching system as well. An experiment with bunched cold beam showed a dependence of the bunch length on the beam density. [ABSTRACT FROM AUTHOR]

Abstract: The longitudinal dynamics of RF-bunched and electron cooled ion beams have been studied at the experimental cooler storage ring (CSRe), at IMP Lanzhou. By RF-bunching the ion beam at the 50th and 100th harmonic of the revolution frequency, the longitudinal momentum spread and the bunch length of the 22Ne10+ ion beam with an energy of 70MeV/u were measured by the new resonant Schottky pick-up and the capacitive pick-up, respectively. A minimum momentum spread of has been reached with less than 107 ions stored in the ring. By using the harmonic potential extracted from the Taylor expansion and the real sinusoidal potential of the bucket, the trend of momentum spread and synchrotron frequency as well as the bunch length as a function of beam current can be interpreted very well. According to this experiment, the RF-buncher is suitable for upcoming experiments on laser cooling of relativistic heavy ion beams at the CSRe. [Copyright &y& Elsevier]

The construction of the high-intensity heavy-ion accelerator facility (HIAF) Yang et al. (2013) [1] at the Institute of Modern Physics, Chinese Academy of Science (IMP, CAS), has begun recently in Huizhou, Guangdong province, China. One of the devices of the HIAF is the Spectrometer Ring (SRing). Designed with two magnetic alloy (MA) loaded cavities to decelerate the heavy-ion beams, such as a 238U + 92 beam from 800 to 30 MeV/u, the SRing will serve as a multi-functional experimental storage ring. The MA cavity design works in the frequency range of 1.006-0.503 MHz with a maximum voltage of 50 kV and peak power of 220 kW. This study describes the variable-harmonic RF deceleration cavity design and a performance test of Chinese MA cores. [ABSTRACT FROM AUTHOR]

The CAFE2 (China Accelerator Facility for superheavy Elements) is a new facility constructed at IMP-CAS (Institute of Modern Physics, Chinese Academy of Sciences). It is based on the upgrade of a superconducting linear accelerator. A new gas-filled recoil separator SHANS2 (Spectrometer for Heavy Atoms and Nuclear Structure-2) with a total flight length path of 5.85 m at the CAFE2 is designed to synthesize and study the superheavy elements, including their physical and chemical properties. The maximum acceptable divergence angles of the SHANS2 are ± 70 mrad and ± 113 mrad in horizontal and vertical directions, respectively, and the maximum magnetic rigidity is 2.5 Tm. The ion-optical design and simulation are investigated in detail, including the first and the fifth order beam optics. The magnets design and magnetic field calculation are presented. Using the 3D field maps, a multiparticle tracking study is carried out for the design validation, trajectory analysis, and performance evaluation. [ABSTRACT FROM AUTHOR]

In the isochronous mass spectrometry (IMS) performed at storage rings, masses of short-lived nuclides are determined through precision measurements of their mean revolution times. However, the distribution of revolution times could be seriously deteriorated by instabilities of the ring's magnetic fields. This becomes a significant obstacle for the particle identifications and mass determinations. A data analysis method is described in this paper which is able to largely remove the uncertainties caused by the magnetic field instabilities in the particle identifications and the mean revolution times. We show that this method is very effective for the IMS experiments even when the magnetic fields of a storage ring vary slowly up to a level of Δ B ∕ B ∼ 1 0 − 4. [ABSTRACT FROM AUTHOR]