Electron Cooling Experiments in CSR

The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u 129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force was measured in different condition.Comment: 5 pages 11 figure

BEAM-PHASE MEASUREMENT SYSTEM FOR HIRFL

The beam phase measurement system in HIRFL is<br />introduced. The system had been improved using RFsignal<br />mixing and filtering techniques and noise<br />cancellation method. Therefore, the influence of strongly<br />RF disturbing was eliminated and the signal to noise rate<br />was increased, and a stable and sensitive phase<br />measurement system was developed. The phase history of<br />the ion beam was detected by using 15 sets of capacitive<br />pick-up probes installed in the SSC cyclotron. The beam<br />phase information was necessary for tuning purposes to<br />obtain an optimized isochronous magnetic field, where<br />the beam intensity was increased and the beam quality<br />was optimized. The measurement results before and after<br />optimized isochronous magnetic field for 40Ar15+ ion and<br />12C6+ ion in SSC were given. The phase measurement<br />system was reliable by optimizing isochronous magnetic<br />field test, and the precision reached &plusmn;0.5o, the sensitivity<br />of beam signal measurement was about 10nA as well

Beam position measurement system at HIRFL-CSRm

Beam position measurement system can not only provide the beam position monitoring, but also be used for global orbit correction to reduce beam loss risk and maximize acceptance. The Beam Position Monitors (BPM) are installed along the synchrotron to acquire beam position with the front-end electronics and data acquisition system (DAQ). To realize high precision orbit measurement in the main heavy ion synchrotron and cooling storage ring of heavy-ion research facility in Lanzhou (HIRFL-CSRm), a series of alignment and calibration work has been implemented on the BPM and its DAQ system. This paper analyzed the tests performed in the laboratory as well as with beam based on the developed algorithms and hardware. Several filtering algorithms were designed and implemented on the acquired BPM raw data, then the beam position and resolution were calculated and analyzed. The results show that the position precision was significantly improved from more than 100 μm to about 50 μm by implementing the new designed filtering algorithm. According to the analyzation of the measurement results and upcoming physical requirements, further upgrade scheme for the BPM DAQ system of CSRm based on field programmable gate array (FPGA) technology was proposed and discussed

Beam loss distribution calculation and collimation efficiency simulation of a cooler storage ring in a heavy ion research facility

The Heavy Ion Research Facility in Lanzhou is an ion cooler storage ring facility in China’s Institute of Modern Physics. The beams are accumulated, electron cooled, accelerated, and extracted from the main cooler storage ring (CSRm) to the experimental ring or different terminals. The heavy ion beams are easily lost at the vacuum chamber along the CSRm when it is used to accumulate intermediate charge state particles. The vacuum pressure bump due to the ion-induced desorption in turn leads to an increase in beam loss rate. In order to avoid the complete beam loss, the collimation system is investigated and planned to be installed in the CSRm. First, the beam loss distribution is simulated considering the particle charge exchanged process. Then the collimation efficiency of the lost particles is calculated and optimized under different position and geometry of the collimators and beam emittance and so on. Furthermore, the beam orbit distortion that is caused by different types of errors in the ring will affect the collimation efficiency. The linearized and inhomogeneous equations of particle motion with these errors are derived and solved by an extended transfer matrix method. Actual magnet alignment errors are adopted to investigate the collimation efficiency of the lost particles in the CSRm. Estimation of the beam loss positions and optimization of the collimation system is completed by a newly developed simulation program

Preparations for laser cooling of relativistic heavy-ion beams at the CSRe

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Laser cooling is one of the most promising techniques to reach high phase-space densities for relativistic heavy-ion beams. Preparations for laser cooling of relativistic lithium-like ions, such as C3+ and N4+, are being made at the experimental cooler storage ring (CSRe) in Lanzhou, China. In December 2011, a new buncher was installed and tested with a 70 MeVu(-1) Ne-22(10+) ion beam by electron cooling at the CSRe. The longitudinal momentum spread of the bunched ion beam was measured by the new resonant Schottky pick-up. As a result, Delta p/p approximate to 2 x 10(-5) has been reached at ion numbers less than 10(7). According to this test result, the RF-buncher is suitable for the upcoming experiment of laser cooling at the CSRe. Laser cooling of heavy-ion beams will also be applied at future storage ring facilities, e. g. FAIR in Darmstadt, and HIAF in Lanzhou.</span

重离子储存环CSRe上激光冷却相对论能量类锂 ~(12)C~(3+)离子束的实验研究进展

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">激光冷却储存环中相对论能量的重离子束是最有希望得到高相空间密度离子束、实现离子束相变并且获得有序束和晶化束的一种方法. 相对于已经比较成熟的随机冷却和电子冷却技术, 储存环上重离子束的激光冷却具有冷却速度快, 冷却作用力强的特点, 可以将离子束冷却到极低温度(mK), 在激光冷却的同时还可以开展高电荷态离子的精细激光谱学实验. 本文介绍了中国科学院近代物理研究所大科学装置重离子冷却储存环CSRe上开展激光冷却重离子束的实验原理和实验方法, 给出了在CSRe上首次激光冷却能量为122 MeV/u的类锂~(12)C~(3+)离子束测试性实验结果, 并且展望了在未来大型加速器HIAF上开展类锂类钠高电荷态离子的激光冷却和精细激光谱学实验.</span><span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Laser cooling of relativistic heavy ion beams at storage rings is one of the most promising techniques to reach high phase-space densities and achieve phase transition, ordered beam even crystalline beam. Compared with the established cooling schemes at storage rings, such as stochastic cooling and electron cooling, laser cooling has many advantages such as fast-cooling, ultra-strong cooling force and providing an ultra-low temperature (mK) ion beams. In addition, the precision laser spectroscopy of the highly charged ions can be performed by using the laser-cooled ion beams during the laser cooling experiments. We introduce the experimental principal and methods of laser cooling of relativistic ion beams at the experimental cooler storage ring of the CSRe at the Institute of Modern Phyics, Chinese Academy of Sciences. The first experimental results from a beam time aiming for laser cooling of 122 MeV/u Li-like ~(12)C~(3+) at the CSRe with a pulsed laser are presented, and laser cooling and precision laser spectroscopy of relativistic Li-like and Na-like highly charged ions at the future large facility HIAF and FAIR are outlined.</span

An online monitor ionization chamber used in particle therapy

The clinical trials of tumor therapy using heavy ions beam C-12 are now in progress at Institute of Modem Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy C-12 beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy C-12 beam in active pencil beam scanning mode.National Nature Science Foundation of China 10305015 10475098 Major Program of the Chinese Academy of Science 0701050YZ