Design of the CAS-LIBB Single-Ion Microbeam Endstation Ⅱ

Cellular micro-irradiation is now recognized as a powerful technique to unveil the mechanisms of interaction between ionizing radiation and living cells or tissues. The single-ion microbeam （SIM） is uniquely capable of delivering precisely the predefined number of charged particles （precise doses of radiation） to specific individual cells or sub-cellular targets in situ. No active research in the field concerning the original process of the interaction between low-energy ions and complicated organisms has been reported yet. To address this challenge, the aim of the present design is to further wrestle with multi-dimensional quantitative information from living cells traversed by an exact number of ions real-time rather than endpoints, in the time scale from milliseconds to days.     

Cell Locating with the Image Analysis System of the CAS-LIBB Single-Particle Microbeam Facility

A single-particle microbeam facility has been constructed at the Key Laboratory ofIon Beam Bioengineering (LIBB), Chinese Academy of Sciences (CAS). At the CAS-LIBB microbeam facility, we have developed protocols to place exact numbers of charged particles through nuclear centroids of cells, at defined positions in the cytoplasm relative to the nucleus, and through defined fractions of cells in a population. In this paper, we address the methods for nucleus, cytoplasm and bystander (either a single or an exact number of ions is delivered to a certain percentage of cells in a population to study the bystander effects of radiation) irradiation in detail from theprecision of target finding and cell locating in the image analysis system. Moreover, for cells touching slightly in an image, a watershed method is used to separate these touching objects;after that, the number of objects in an image is counted accurately and the irradiation points are located precisely.     

Experimental Status of the HANBIT Facility

HANBIT is a magnetic mirror confinement device. Recent physics experiments have been mainly focused on identifying discharge characteristics and on getting stable plasma production and operation modes, by using a 500 kW slot antenna system at a fixed RF frequency of 3.5 MHz and varying discharge conditions such as fueling rate, RF power, and B-field intensity in central cell. Two distinct operation modes are found to be very sensitive to the RF power as well as the ratio of the RF frequency to the ion cyclotron frequency. A MHD interchange mode of m- -1 is clearly observed and the stabilizing mechanism can be explained by the sideband coupling theory.     

Alterations of mtDNA copy number and 4977 bp deletion induced by ionizing radiation in human peripheral blood

Alterations of mitochondria DNA （mtDNA） 4977 bp common deletion （CD） and mtDNA copy number induced by ionizing radiation were observed in human different cell lines and total body irradiation patients. However, only few experiments have evaluated the levels of the CD and mtDNA copy number in human peripheral blood exposed to ionizing radiation till now. The aim of this study is to analyze the mtDNA alterations in irradiated human peripheral blood from healthy donors as well as to explore their feasibility as biomarkers for constructing new biodosimeter. Peripheral blood samples were collected from six healthy donors, and exposed to 6~Co gamma ray with the doses of 0 Gy, 1 Gy, 2 Gy, 3 Gy, 4 Gy and 5 Gy. Levels of the CD and mtDNA copy number in irradiated samples after 2h or 24h incubation were detected using TaqMan real-time PCR, and the CD ratio was calculated. The results showed that the mean of the CD ratio and the CD copy number exhibited a dose-dependent increase 2 h in the dose range from 0-5 Gy, and of the mtDNA copy number significantly increased 24 h in irradiated groups compared with 0 Gy group after irradiation. It indicates that the parameters in human peripheral blood may be considered as molecular biomarkers to applying construction of new biodosimeter.     

Transient Ablation Regime in Circuit Breakers

Nozzle wall ablation caused by high temperature electric arcs is studied in the context of high voltage SF6 circuit breakers. The simplified ablation model used in litterature has been updated to take into account the unsteady state of ablation. Ablation rate and velocity are now calculated by a kinetic model using two layers of transition, between the bulk plasma and the ablating wall. The first layer （Knudsen layer）, right by the wall, is a kinetic layer of a few mean-free path of thickness. The second layer is collision dominated and makes the transition between the kinetic layer and the plasma bulk. With this new coupled algorithm, it is now possible to calculate the temperature distribution inside the wall, as well as more accurate ablation rates.     

Dosimetric Analyses of Single Particle Microbeam in Cell Irradiation Experiment

Single particle microbeam （SPM） is uniquely capable of delivering precisely the predefined number of charged particles to determined individual cells or sub-cellular targets in situ. It has been recognized as a powerful technique for unveiling ionization irradiation mechanisms of organism. This article describes some investigations on the irradiation quality of SPM of major world laboratories by means of Monte Carlo method based on dosimetry and microdosimetry. Those parameters are helpful not only to improve SPM irradiating cell experiments but also to study the biological effects of cells irradiated by SPM.     

The Progress of a Microbeam Facility in the Institute of Plasma Physics

The progress of a microbeam facility in the institute of Plasma Physics was discussed in this paper.This kind of equipment can supply single-particle beam which may be implanted into cells in micrometer-radius and measured by a new outstanding detector among global microbeam systems.Measurements by some plain targets showed that the highest current after the accelerator tube can be larger than 20μA ,the H2^ current before the second bending magnet is near 0.9μA ,the current after the second bending magnet is near 0.8μA,and the current of the beam line(after a 2-mm diameter aperture)is near 0.25nA which is enough for the single-particle microbeam experiment.It took scientists 3 months to do their microbeam experiment after setting up the qccelerator beam line and get the microbeam from this equipment.Two pre0collimators were installed between the 2-mm diameter aperture and the collimator to survey the beam.Tracks on the CR39 film ectched in the solution of NaOH showed that the beam can go through the collimator including a 10μm diameter aperture and the 3.5μm thick vacuum sealing film(Mylar).A new method,which is called optimization of the beam quality,was put forward in this paper,in order to get smaller diameter of beam-spot in microbeam system.     

Typical Nuclear Material Accounting Simulation of Spent Fuel Reprocessing Plant

<正>The nuclear material accounting in spent fuel reprocessing plant,equipped with huge number measurement points,is a complex system.It is difficult to obtain the dynamic process of the material accounting by the MUF orσMUF calculation as well as analyze the system systematically.The simulation is an effective method to study complex systems,by which a simulation model can be built with the reprocessing logic directly and avoiding the mathematical abstract difficulty.     

Measurement of electron density and electron temperature of a cascaded arc plasma using laser Thomson scattering compared to an optical emission spectroscopic approach

As advanced linear plasma sources, cascaded arc plasma devices have been used to generate steady plasma with high electron density, high particle flux and low electron temperature. To measure electron density and electron temperature of the plasma device accurately, a laser Thomson scattering(LTS) system, which is generally recognized as the most precise plasma diagnostic method, has been established in our lab in Dalian University of Technology. The electron density has been measured successfully in the region of 4.5?×?10(19)m~(-3) to7.1?×?10~(20)m~(-3) and electron temperature in the region of 0.18 eV to 0.58 eV. For comparison,an optical emission spectroscopy(OES) system was established as well. The results showed that the electron excitation temperature(configuration temperature) measured by OES is significantly higher than the electron temperature(kinetic electron temperature) measured by LTS by up to 40% in the given discharge conditions. The results indicate that the cascaded arc plasma is recombining plasma and it is not in local thermodynamic equilibrium(LTE). This leads to significant error using OES when characterizing the electron temperature in a non-LTE plasma.     

Pulsed intense electron beam emittance measurement

Recently we measured with the Modified Three Gradient Method(MTGM) the beam emittance of an injector constructed in 2012, which was designed to provide a 2.4 kA, 2.6 MeV electron beam. The MTGM is a non-intercept indirect method, which is based on the three gradient type measurements of beam profiles and subsequent data processing which helps to get the least square solution to the beam emittance. Beam profiles under different currents of guiding coil are measured using Cerenkov radiation given off by a piece of quartz glass in the beam tube, which is recorded with a CCD camera. MTGM Code is developed to realize the data fitting as well as beam transport simulation, in which both the σ matrix method and the numerical solution of root-mean-square beam envelope equation are used. The error is also analyzed.     

α粒子微束定点照射--细胞的放射生物学效应及精确性分析

进行微束试验的关键是能够精确地控制照射的粒子数和将粒子准确地射入受照射位点.该研究通过对哥伦比亚大学单粒子微束装置在精确性、准确性以及各项指标的分析发现该装置可精确地控制照射粒子数,精确率为98.4%.同时,它可将α粒子准确地射入受照射位点,束半径为34,达到设计4的标准.在对细胞特定位点如细胞质照射上,粒子击中细胞质至少一个位点的概率为90%,在这一过程中的偶然核击中率,对大多数照射剂量(8个粒子)均小于0.8%.应用该微束装置的放射生物学研究发现单个α粒子仅导致大约20%的致死率,其存活率曲线类似于用常规照射获得的平均粒子存活曲线.诱变试验首次证实单个α粒子在AL细胞的CD59基因位点可诱导出比对照高出3倍数量的诱变子,诱变率随粒子数的增加而增加.这一结果不同于常规照射中,诱变率在高剂量照射后下降的结论.     

复旦大学单粒子微束研制进展

建设了一基于复旦大学2×3 MV串列加速器的单粒子微束装置。离子束经分析磁铁30°水平偏转传输后再经90°偏转磁铁竖直上行至辐照终端,以内径1.5 μm的毛细玻璃管微准直器获取离子微束。采用薄膜闪烁体结合光电倍增管的探测结构对微束离子进行精确探测和计数,并以高压静电偏转开关快速关断束流以实现对离子数目的精确控制。目前实验已获得在质子能量为3 MeV时,能散（能量分布曲线中半高宽FWHM）<60 keV、束分辨<2.2 μm、定量照射精度>95%的质子微束。本文对复旦大学单粒子微束的束流管道设计、微束获取、束开关及单粒子探测等核心环节的研制进展进行介绍。     

微束单细胞照射的研究和发展

了解低剂量辐射效应等辐射生物学基本问题的关键是研究单一粒子与生物体的相互作用。然而 ,由于粒子在能量、径迹上的随机分布 ,这种单一粒子与生物体的相互作用很难在实验室中用常规照射的方法进行。微束的发展 ,特别是单粒子微束通过将精确数量的粒子准确地射入细胞或细胞的特定位置为回答这些问题提供了一个直接 ,有用的手段。该文论述了微束的历史 ,现状和未来发展 ,以及微束在辐射生物学研究中的应用。     

The Columbia University proton-induced soft x-ray microbeam

A soft X-ray microbeam using proton-induced X-ray emission (PIXE) of characteristic titanium (K_α 4.5 keV) as the X-ray source has been developed at the Radiological Research Accelerator Facility (RARAF) at Columbia University. The proton beam is focused to a 120 μm × 50 μm spot on the titanium target using an electrostatic quadrupole quadruplet previously used for the charged particle microbeam studies at RARAF. The proton induced X-rays from this spot project a 50 μm round X-ray generation spot into the vertical direction. The X-rays are focused to a spot size of 5 μm in diameter using a Fresnel zone plate. The X-rays have an attenuation length of (1/e length of ∼145 μm) allowing more consistent dose delivery across the depth of a single cell layer and penetration into tissue samples than previous ultrasoft X-ray systems. The irradiation end station is based on our previous design to allow quick comparison to charged particle experiments and for mixed irradiation experiments.     

Application of heavy-ion microbeam system at Kyoto University: Energy response for imaging plate by single ion irradiation

A heavy-ion microbeam system for cell irradiation has been developed using an accelerator at Kyoto University. We have successfully developed proton-, carbon-, fluorine- and silicon-beams in order to irradiate a micro-meter sized area with ion counting, especially single ion irradiation. In the heavy-ion microbeam system, an imaging plate (IP) was utilized for beam diagnostics on the irradiation. The IP is widely used for radiography studies in biology. However, there are a few studies on the low linear energy transfer (LET) by single ions, i.e., low-intensity exposure. Thus we have investigated the energy response for the IP, which can be utilized for microbeam diagnostics.     

Heavy-ion microbeam system for cell irradiation at Kyoto University

We have developed a heavy-ion microbeam system for cell irradiation that uses an 8-MV tandem Van de Graaff accelerator at Kyoto University. Using a pair of apertures as the final collimator, microbeams of carbon, fluorine, and silicon were extracted to the atmosphere with few background particles. We used a thin transmission scintillator and a photomultiplier detector to accurately measure the number of extracted particles. To examine beam spreading, the beam profile was measured by observing tracks of an irradiated CR-39 track detector. The two disks with holes which were added to the collimating apertures reduced background radiation due to secondary X-rays and electrons from the apertures.     

The PTB single ion microbeam for irradiation of living cells

At the PTB's ion accelerators, a new microbeam facility is now in operation that is capable of delivering single ions, for example, to the nuclei of individual living cells. The wide range of proton and ⁴He²⁺ ion energies affords LET-values between 3 and 200 keV/μm. A beam diameter of less than 2 μm outside the vacuum system has been measured and a targeting accuracy of better than 2 μm has been determined. In contrast to other microbeam facilities operated for radiobiological research using mechanical collimators in front of the target to define the beam, the PTB facility utilises beam focusing by quadrupole magnets. The microbeam has a unique ion optical design that incorporates a 90° bending magnet in the beam transport system. This design has the advantage of providing a microbeam basically without scattered particles. Every ion reaching the target is detected by a thin scintillating foil and a photomultiplier tube with efficiency close to 100%. Presently up to 1500 single cells per hour can be automatically irradiated with a chosen number of particles. Procedures and results of first cell irradiations are described as an example.     

Pseudo-cubic thin-plate-type spline method for analysing experimental data

This paper recalls the statistical origins of the minimum departure from nucleate boiling ratio (MDNBR) concept and Owen's coefficients, as used in CHF studies. The way in which they are currently used may be incorrect, and we shall present a new approach in which the lower tolerance interval limit depends on a number of parameters. The use of least-square regressions and smoothing splines is explained. We also include an example, based on a CHF EPRI test, from the Columbia University data bank.     

同步辐射硬X射线微束技术

同步辐射硬X射线微束(微探针)技术是目前很多学科领域的主流分析技术,本文介绍了同步辐射硬X射线的各种微束技术以及微束的应用研究情况,阐述了各种微束技术的基本聚焦原理,并对其优势和不足以及发展状况作了简要的概述.