H W Zhao

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (800)2768.35 Total impact

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    ABSTRACT: To prepare the upcoming experiment of laser cooling of relativistic 12 C 3+ ion beams at the experimental cooler storage ring (CSRe), a test experiment was performed with 12 C 3+ ion beams at an energy of 122 MeV/u on the CSRe, at the Institute of Modern Physics, Lanzhou, China. In this experiment, the main storage ring of CSRm was employed to accumulate and accelerate the ion beam which was injected into the CSRe for the experiments. The number of 12 C 3+ ions at the CSRe reached 5×10 8 for every injection, which satisfied the experimental requirement. To fulfil the laser cooling experiment, the 12 C 3+ ion beams were bunched by sinusoidal waveforms with fixed and sweeping frequencies, respectively. A resonant Schottky pick-up was employed to record the Schottky spectra of these ion beams. The test experimental results demonstrated that the RF-buncher and diagnostic systems at the CSRe worked well and the CSRe was very stable with 12 C 3+ ion beams, hereby the CSRe is suitable for laser cooling experiment. 1. Introduction Realizing a crystalline ion beam is one of the ultimate goals of laser cooling of heavy ion beams at the storage rings. Laser cooling has been considered to be the only one method to realize the crystalline ion beams at the storage ring because of its extremely narrow and strong cooling force [1, 2]. The other motivation for laser cooling at the experimental cooler storage ring (CSRe) at IMP and the ESR at GSI is to extend this technique to the future large accelerator facilities, such as the Facility for Antiprotons and Ion Research (FAIR) at Darmstadt in Germany [3] and the High Intensity heavy ion Accelerator Facility (HIAF) at Lanzhou in China [4]. The precision nuclear and atomic experiments with highly charged ions will greatly benefit from ion beams with ultra-low momentum spread. Therefore powerful cooling techniques are important for future high-quality relativistic heavy ion beams. Compared to the normal laser cooling experiment at traps [5, 6] and low-energy storage rings [7], laser cooling of relativistic heavy ions can only rely on laser beams counter-propagating with the ion beams and the laser cooling force is predicted to principally increase with the third power of the ion energy due to the fast transition rates in highly charged ions and relativistic Doppler shift [8]. Fortunately, the method by combining only one laser beam and a RF-buncher to cool the ion beams at
    17th International Conference on the Physics of Highly Charged Ions, 31 August to 5 September 2014, San Carlos de Bariloche, Argentina; 01/2015
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    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.
    European Physical Journal C 11/2014; DOI:10.1140/epjc/s10052-014-3026-9 · 5.25 Impact Factor
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    ABSTRACT: Experimental evidence of the property of transverse coupling of beam from Electron Cyclotron Resonance (ECR) ion source is presented. It is especially of interest for an ECR ion source, where the cross section of extracted beam is not round along transport path due to the magnetic confinement configuration. When the ions are extracted and accelerated through the descending axial magnetic field at the extraction region, the horizontal and vertical phase space strongly coupled. In this study, the coupling configuration between the transverse phase spaces of the beam from ECR ion source is achieved by beam back-tracking simulation based on the measurements. The reasonability of this coupling configuration has been proven by a series of subsequent simulations.
    Review of Scientific Instruments 11/2014; 85(11):113305. DOI:10.1063/1.4901591 · 1.58 Impact Factor
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    ABSTRACT: HIRFL, is consists of the ECR ion source, cyclotron of SFC, SSC, and CSRm, CSRe, had been installed and started commission from 2005. Two injection modes of the stripping injection and MMI with electron cooling were tuned successful. The typical gains of accumulation from 7 to 60 were obtained by single multi-turn injection or multiple multi-turn injections (MMI) respectively. The beam momentum spread typical from 4×10-3 is cooling to 2×10-4. The life time of storage beam with electron cooling are about 10 second for 2.86MeV/u Xe and >1000 s for 7MeV/u C. The beams were accelerated by switching the harmonic number 2 (4) to 1during ramping. So far, three kinds of beams, 10^9ppp of 12C6+, 10^8 ppp of 36Ar18+ and 10^8 ppp of 129Xe27+ were accelerated to 1000MeV/u, 235MeV/u and extracted from CSRm respectively. The beam has past RIBLL-II and inject into CSRe. Detail commissioning of CSRe is ongoing. After test run on CSRe, HIRFL-CSR is reviewed before end of this year and will open for user next year.
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    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. DOI:10.1016/j.nima.2014.04.051 · 1.32 Impact Factor
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    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. DOI:10.1016/j.nima.2014.04.031 · 1.32 Impact Factor
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    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 07/2014; 85(7):073304-073304-4. DOI:10.1063/1.4890155 · 1.58 Impact Factor
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    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
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    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
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    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. DOI:10.1016/j.physletb.2014.06.046 · 6.02 Impact Factor
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    Y Yang, L T Sun, X Z Zhang, H W Zhao
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    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.
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    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. DOI:10.1063/1.4847275 · 1.58 Impact Factor
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    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. DOI:10.1063/1.4827113 · 1.58 Impact Factor
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    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. DOI:10.1063/1.4832935 · 1.58 Impact Factor
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    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. DOI:10.1063/1.4824804 · 1.58 Impact Factor
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    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. DOI:10.1063/1.4827575 · 1.58 Impact Factor

Publication Stats

4k Citations
2,768.35 Total Impact Points

Institutions

  • 2000–2015
    • Chinese Academy of Sciences
      • • Institute of Modern Physics
      • • State Key Laboratory of Magnetism
      Peping, Beijing, China
    • Nankai University
      T’ien-ching-shih, Tianjin Shi, China
  • 2011
    • Université Paris-Sud 11
      Orsay, Île-de-France, France
  • 2005–2010
    • National Space Science
      Peping, Beijing, China
  • 2006–2009
    • Université de Savoie
      Chambéry, Rhône-Alpes, France
  • 2001
    • Colorado State University
      • Department of Physics
      Fort Collins, Colorado, United States
    • Aomori University
      Aomori, Aomori Prefecture, Japan
    • Chuo University
      Edo, Tōkyō, Japan
  • 1998
    • Hangzhou University
      Shanghai, Shanghai Shi, China