[Show abstract][Hide abstract] ABSTRACT: In isochronous mass spectrometry (IMS) established in heavy-ion storage rings the revolution times of the stored secondary ions should be independent of their velocity spread. However, this isochronous condition is fulfilled only in first order and in a small range of revolution times. To correct for the non-isochronicity an additional measure of the velocity or magnetic rigidity of each stored ion is required. For this purpose two new time-of-flight (TOF) detectors were installed in a straight section of the experimental Cooler Storage Ring CSRe in Lanzhou. The performance of the new time-of-flight (TOF) detectors, which is crucial for the achievable efficiencies and mass resolving power, was significantly improved. The time resolution of the TOF detector in offline tests was σ=18.5±2ps. The detector setup was put into operation with a stable beam of 78Kr.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 08/2014; 756:1. · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Accuracy of nuclear mass measurements in storage rings depends critically on the accuracy with which the revolution times of stored ions can be obtained. In such experiments, micro-channel plates (MCP) are used as timing detectors. Due to large phase space of injected secondary beams, a large number of ions cannot be stored in the ring and is lost within the first few revolutions. However, these ions interact with the detector and can saturate the MCP and thus deteriorate its performance. In order to eliminate such effects, a fast, pulsed high-voltage power supply (PHVPS) has been employed which keeps the detector switched-off during the first few revolutions. The new detector setup was taken into operation at the Experimental Cooler-Storage-Ring CSRe in Lanzhou and resulted in a significant improvement of the detector amplitude and efficiency characteristics.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 08/2014; 755:38. · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This work is on the Physics of the B Factories. Part A of this book contains
a brief description of the SLAC and KEK B Factories as well as their detectors,
BaBar and Belle, and data taking related issues. Part B discusses tools and
methods used by the experiments in order to obtain results. The results
themselves can be found in Part C.
[Show abstract][Hide abstract] ABSTRACT: The project of SSC-LINAC RFQ has important progresses in the past year. The machine has been moved to the Institute of Modern Physics in the first season of 2013. The cavity measurement including tests of RF performance and field distribution is carried out again in the laboratory. The Q 0 is 6440, and the unflatness of the electric field in longitudinal is ±2.5%. The results demonstrated a good agreement with simulation. The RF and beam commissioning of the RFQ has been carried out in the first half of 2014. The duty factor rose from 5% to CW gradually. By now, the cavity has been operated with 35 kW on CW mode. The measurement of the bremsstrahlung spectrum reveals that the 35 kW power is needed to generate the 70 kV inter-vane voltage. The beam transmission efficiency and energy spread has been obtained in beam commissioning by accelerating 16 O 5+ and 40 Ar 8+ beams. The efficiency of 40 Ar 8+ is as high as 94%, and the output energy is 142.78 keV/u. All the processes and results of the experiments will be discussed in details.
International Particle Accelerator Conference, 2014; 06/2014
[Show abstract][Hide abstract] ABSTRACT: A powerful heavy ion injector SSC-linac is under constructing at IMP in Lanzhou. The continuous wave (CW) 4-rod RFQ operating at 53.667 MHz has been developed as the low beam energy injector linac. The 40 Ar 8+ ion beam extracted from the ECR ion source was used for the RFQ commissioning. The particle energy 142.8 keV/u and the 198 ePA beam current were measured at the exit of RFQ with the 94% transmission. In this paper, the recent R&D progress of the SSC-LINAC including the development of key components and the beam commissioning results are presented.
International Particle Accelerator Conference, 2014; 06/2014
[Show abstract][Hide abstract] ABSTRACT: Revolution frequency measurements of individual ions in storage rings require sophisticated timing detectors. One of common approaches for such detectors is the detection of secondary electrons released from a thin foil due to penetration of the stored ions. A new method based on the analysis of intensities of secondary electrons was developed which enables determination of the charge of each ion simultaneously with the measurement of its revolution frequency. Although the mass-over-charge ratios of 51Co27+ and 34Ar18+ ions are almost identical, and therefore, the ions cannot be resolved in a storage ring, by applying the new method the mass excess of the short-lived 51Co is determined for the first time to be ME(Co51)=−27342(48) keV. Shell-model calculations in the fp-shell nuclei compared to the new data indicate the need to include isospin-nonconserving forces.
Physics Letters B 06/2014; 735:327-331. · 4.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Heavy-Ion Advanced Research Facility (HIAF) is a new project proposed at Institute of Modern Physics (IMP) in China. HIAF project accelerator is composed of intense ion beam sources, injector superconducting LINAC, acceleration and accumulation storage ring, a collection ring and a collider ring. To achieve the ultimate project goal, HIAF accelerator requires the ion source to provide very high intensity of heavy ion beams, such as 1.7 emA 238 U 34+ with a repetition rate of 5 Hz and pulse length of 0.5 ms. No state-of-the-art ion source can meet the needs. As a baseline of the project, a high performance superconducting ECR ion source, which is designed to be operational at the microwave frequency of 40-60 GHz will be adopted to produce the pulsed beam of interest for the HIAF accelerator. To transport and match the beams from ECR to the downstream RFQ, a low energy beam transport (LEBT) is needed. This paper presents a preliminary design of the LEBT and the beam dynamics in the LEBT.
[Show abstract][Hide abstract] ABSTRACT: Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou (SECRAL) is an advanced fully superconducting ECR ion source at IMP designed to be operational at the microwave frequency of 18-24 GHz. The existing SECRAL beam transmission line is composed of a solenoid lens and a 110° analyzing magnet. Simulations of particle tracking with 3D space charge effect and realistic 3D magnetic fields through the line were performed using particle-in-cell code. The results of the beam dynamics show that such a low energy beam is very sensitive to the space charge effect and significantly suffers from the second-order aberration of the analyzing magnet resulting in large emittance. However, the second-order aberration could be reduced by adding compensating sextupole components in the beam line. On this basis, a new 110° analyzing magnet with relatively larger acceptance and smaller aberration is designed and will be used in the design of low energy beam transport line for a new superconducting ECR ion source SECRAL-II. The features of the analyzer and the corresponding beam trajectory calculation will be detailed and discussed in this paper.
The Review of scientific instruments 02/2014; 85(2):02A719. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Superconducting ECR ion sources can produce intense highly charged ion beams for the application in heavy ion accelerators. Superconducting Electron Resonance ion source with Advanced Design (SECRAL) is one of the few fully superconducting ECR ion sources that has been successfully built and put into routine operation for years. With enormous efforts and R&D work, promising results have been achieved with the ion source. Heated by the microwave power from a 7 kW/24 GHz gyrotron microwave generator, very intense highly charged gaseous ion beams have been produced, such as 455 eμA Xe(27+), 236 eμA Xe(30+), and 64 eμA Xe(35+). Since heavy metallic ion beams are being more and more attractive and important for many accelerator projects globally, intensive studies have been made to produce highly charged heavy metal ion beams, such as those from bismuth and uranium. Recently, 420 eμA Bi(30+) and 202 eμA U(33+) have been produced with SECRAL source. This paper will present the latest results with SECRAL, and the operation status will be discussed as well. An introduction of recently started SECRAL II project will also be given in the presentation.
The Review of scientific instruments 02/2014; 85(2):02A942. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Evaporative cooling technology utilizes phase-change heat transfer mode to achieve the cooling for heating equipment. The heat transfer capacity of evaporative cooling technology is far more than air or water cooling technology. The Electron Cyclotron Resonance ion source magnet is a typical super-high power density magnet, and the evaporative cooling technology is an ideal cooling method for the coils of magnet. In this paper we show the structure and process of coils and the special design of flow channels of coolant for an experiment magnet model. Additionally, the heat transfer circulation is presented and analyzed. By the finite element method, the flow channels are optimized to rationally allocate coolant and to reduce the temperature of coils. For the experiment model, the current density of copper wire of coils is 19 A/mm(2), and the coil-windows current density is larger than 12 A/mm(2). The max temperature of coils is below 80 °C, and the total heat is about 200 kW.
The Review of scientific instruments 02/2014; 85(2):02A913. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A new room temperature ECR ion source, Lanzhou Electron Cyclotron Resonance ion source No. 4 (LECR4, previously named DRAGON), is under intense construction at Institute of Modern Physics. LECR4 is designed to operate with 18 GHz microwave frequency. The maximum axial magnetic fields are 2.3 T at injection and 1.3 T at extraction, and the radial field at the plasma chamber wall of 76 mm inner diameter is 1.0-1.2 T. One of the unique features for LECR4 is that its axial solenoids are winded with solid square copper wires which are immersed in a kind of special evaporative cooling medium for cooling purpose. Till now, a prototype of the cooling system has been successfully constructed and tested, which has demonstrated that the cooling efficiency of the designed system could meet the requirements of LECR4 under the routine operation conditions. All the main components of the ion source have been completed. Assembly and commissioning is ongoing. The latest developments and test results will be presented in this paper.
The Review of scientific instruments 02/2014; 85(2):02A926. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A negative hydrogen (H(-)) ion source with hot cathode arc discharge was designed and fabricated as a primary injector for a 10 MeV PET cyclotron at IMP. 1 mA dc H(-) beam with ɛ N, RMS = 0.08 π mm mrad was extracted at 25 kV. Halbach hexapole was adopted to confine the plasma. The state of arc discharge, the parameters including filament current, arc current, gas pressure, plasma electrode bias, and the ratio of [Formula: see text] were experimentally studied. The discussion on the result, and opinions to improve the source were given.
The Review of scientific instruments 02/2014; 85(2):02B120. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: At Institute of Modern Physics, a cw 35 keV, 20 mA intense proton source and the low energy beam transport system (LEBT) have been developed for China Initiative Accelerator Driven Sub-Critical reactor system. In order to ensure high quality transmission of the intense ion beam from the exit of ion source to Radio Frequency Quadrupole (RFQ), a low energy beam transport line is used to focus beam to the RFQ entrance and match the Twiss parameters to the RFQ requirements. The 35 keV, 20 mA ion beam extracted by a three-electrode extraction system from the ion source passes through the LEBT to the RFQ entrance and the root-mean-square emittance is measured to be less than 0.2 π mm mrad. The commissioning results of the ion source and low energy beam transport system are described in this paper. The beam quality and transmission efficiency are also studied.
The Review of scientific instruments 02/2014; 85(2):02A703. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The direct plasma injection scheme (DPIS) has been being studied at Institute of Modern Physics since several years ago. A C6+ beam with peak current of 13 mA, energy of 593 keV/u has been successfully achieved after acceleration with DPIS method. To understand the process of DPIS, some simulations have been done as follows. First, with the total current intensity and the relative yields of different charge states for carbon ions measured at the different distance from the target, the absolute current intensities and time-dependences for different charge states are scaled to the exit of the laser ion source in the DPIS. Then with these derived values as the input parameters, the extraction of carbon beam from the laser ion source to the radio frequency quadrupole with DPIS is simulated, which is well agreed with the experiment results.
Review of Scientific Instruments 01/2014; 85(7):073304-073304-4. · 1.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The HIRFL–CSR, as an upgrade of the HIRFL, has been put into operation since 2008. Together with a series of improvements of injector cyclotrons, the HIRFL is in a very good state and can provide all ion species from proton to uranium with energy variable from ion source energy to 1 GeV/u (A/q = 2). Present status of the HIRFL–CSR complex is given. Main features realized during the commissioning and operation are described in detail. The progress on physics experiments and cancer therapy are also presented.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 12/2013; 317:214-217. · 1.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: HIAF (High Intensity heavy ion Accelerator Facility), a new facility
planned in China for heavy ion related researches, consists of two ion
sources, a high intensity Heavy Ion Superconducting Linac (HISCL), a 45
Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage
ring system. The key features of HIAF are unprecedented high pulse beam
intensity and versatile operation mode. The HIAF project aims to expand
nuclear and related researches into presently unreachable region and
give scientists possibilities to conduct cutting-edge researches in
these fields. The general description of the facility is given in this
article with a focus on the accelerator design.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 12/2013; · 1.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An electron diode using a short section of dielectric wall accelerator
(DWA) has been under development at the Institute of Modern Physics
(IMP), Chinese Academy of Sciences. Tests have been carried out with
spark gap switches triggered by lasers. The stack voltage efficiency of
a four-layer of Blumleins reached about 60-70% with gas filled spark gap
switching. The generated pulse voltage of peak amplitude of 23 kV and
pulse width of 5 ns is used to extract and accelerate an electron beam
of 320 mA, measured by a fast current transformer. A nanosecond pulse
width electron diode was achieved successfully. Furthermore, the
principle of a DWA is well proven and the development details and
discussions are presented in this article.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2013; · 1.14 Impact Factor