2016年 第33卷 第4期
The significance and principle of lifetime measurements of excited states in nuclei are briefly described. By using the recoil-distance Doppler-shift method, the Doppler-shift attenuation method, and the fast-timing technique established at the in-beam γ terminal of HI-13 tandem accelerator, nuclear structure studies on topical subjects including chiral symmetries and magnetic rotation have been performed. Our experimental results indicate that 130Cs shows better chiral characteristics, however, the two candidate bands of 106Ag could not be a pair of chiral doublet bands. For magnetic rotation, the deduced B(M1) values deduced from the measured level lifetimes clearly demonstrate that the yrast positive-parity band in 106Ag and both the yrast positiveand negative-parity bands in 107Ag are magnetic rotation bands. In addition, our lifetime measurement data also provide valuable experimental evidences for the interpretation and understanding of the shape evolution, the shape coexistence, and the critical-point symmetries of shape phase transition in the different isotope chains.
Dynamics of heavy-ion fusion and nuclear fission system in a quantum non-Ohmic environment have been considered and a numerical simulation method to solve the corresponding c-number quantum generalized Langevin equation is proposed. The method of generating quantum colored noise with arbitrary correlation can be applied to generate noise of arbitrary non-Markov process. Calculating fusion probability of heavy nuclei with this method, the result has shown that the passing probability is enlarged (decreased) by the quantum fluctuation when the initial kinetic energy of the particle is less than (greater than) the critical initial kinetic energy. Steady passing probability of particle in non-Ohmic environment versus is nonmonotonic. Quantum fluctuation makes the maximum position of the curve drift towards right (left), when the initial kinetic energy of the particle is less than (greater than) the critical initial kinetic energy. Furthermore, nuclear fission rate is larger in super-Ohmic environment. Quantum fluctuation enlarges nuclear fission rate and makes the the maximum position of nuclear fission rate versus δ drift.
评述了天体物理中暗物质的发现以及标准模型所面临的问题，综述了解决这些问题及标准模型之外可能出现的新物理与暗物质的联系。介绍了暗物质粒子选择条件和可能的暗物质粒子的候选者；对圆柱形暗物质表面密度与星系和星系团暗物质晕的晕核半径的关系进行了讨论，与其他模型进行了比较，得出暗物质晕的特征半径r*的暗物质表面密度分布不是一个普适量；并叙述了近几年暗物质研究中提出的新理论模型-Hidden dark matter，最后叙述了中国暗物质实验探测研究的进展，2016年底DAMPE的第一批数据有可能给出；中国锦屏地下实验室（CJPL）的CDEX和PandaX合作组的第一期实验没有发现暗物质粒子存在的信号，期待他们下期的实验。
A review of the evidence of the dark matter found in universe and the problems faced by the standard model. To address these issues as well as the possible relationship between the new physics beyond the standard model and dark matter, and given the selection condition of dark matter and possible candidates of the weakly-interacting massive particles (WIMPs). The correlation between the column surface density and the halo core radius of the dark matter halos of galaxies and cluster of galaxies is discussed, and the other models are compared. We find that the surface density within the halo characteristic radius r* is not an universal quantity; The new model (hidden dark matter)proposed in the study of dark matter is described. At last, the research progress of dark matter experiment in China is commented. At the end of 2016, the first batch of DAMPE data may be given;No significant excess events of WIMPS were found in the first stage of both the CDEX and PandaX experiments located in the China Jinping Underground Laboratory(CJPL). Look forward to their the next stage of these experiments in CJPL.
We study the scalar meson f0(980) in the γp→pf0(980) reaction within an effective Lagrangian approach. Based on previous studies, we calculate the differential cross sections of this reaction. We take two types of the propagators of vector mesons ρ and ω, one is the Regge form, the other one is the normal Feynman propagator. It is found that our theoretical results for the differential cross sections with the Feynman propagator are in agreement with the current experimental data. For the total cross sections, the results with the two types of propagator are much different. On the other hand, we predict the π+π- invariant mass distribution of the γp→pf0(980)→pπ+π- reaction. We find that the π+π- invariant mass distribution depends sensitively on the value of the coupling constant gf0KK. We hope that the future experiments can test our model calculation and give further constraints on the value of gf0KK and also the nature of f0(980).
应用多源热模型研究了相对论性重离子对撞机（RHIC）上PHENIX合作组测得的每核子对质心能量√sNN=200 GeV的氘-金（d+Au）碰撞中快度长程方位角关联，和大型强子对撞机（LHC）上CMS合作组测得的质心能量√s=0.9，2.36，7 TeV的质子质子（p+p）碰撞中高多重数短程赝快度关联，在误差范围内模型结果很好地重现了实验数据。用4个参数分析了长程方位角关联，结果表明，参数可以清楚地显示出脊结构的变化趋势，说明脊结构与集体效应、流体力学流效应、粒子对的横动量及信号等有关。用3个参数分析了小系统高多重数短程赝快度关联，结果表明，参数σ和c3与能量相关，能量越大，两粒子越靠近，关联越强。
The multi-source thermal model is used in this paper to analyze the long-range azimuth correlation in deutron-gold (d+Au) collisions at center-of-mass energy per nucleon pair √sNN=200 GeV measured by the PHENIX Collaboration at the relativistic heavy ion collider (RHIC), and the short-range pseudorapidity correlation in high multiplicity event in proton-proton (p+p) collisions at center-of-mass energy √s=0.9, 2.36, 7 TeV measured by the CMS Collaboration at the large hadron collider (LHC). The modeling results are in approximately agreement with the experimental data in error ranges. Four parameters are used in the analysis of long-range azimuth correlation, which show that the parameters describe the change trend of ridge structure. The ridge structure is related to the collective effect, hydrodynamic flow effect, transverse momentum and signal of particle pair, and so forth. Three parameters are used in the analysis of the short-range pseudorapidity correlation in high multiplicity event in small system, which show that the parameters σ and c3 are related to collision energy. Large collision energy results in strong correlation due to close distance between particles.
对290 AMeV 12C诱发乳胶核反应末态粒子间的多重数关联进行了研究。实验结果表明：黑径迹粒子、灰径迹粒子、重电离粒子多重数之间存在较强的关联，而且黑径迹粒子和重电离粒子多重数有饱和的趋势，这些特征与高能区实验结果一致；簇射粒子与其他粒子间的关联性较弱，这一特征与高能区实验结果不同，主要归因于弹核能量较低、簇射粒子产额较小；黑径迹粒子、灰径迹粒子在前后半球的平均多重数随靶核的增大而增加；实验结果可用基于碰撞几何的旁观体-反应体模型及级联蒸发模型来解释。
We have investigated the multiplicity correlation of particles produced in 12C-emulsion interactions at 290 AMeV. It is found that there is a strong correlation between black track particle, grey track particle and heavily ionized track particle, and finally black track particles and heavily ionized track particles tend to saturation, which is the same as the experimental results observed at high energies. The multiplicity correlation between shower particle and other particles is weaker, which is different from the experimental results observed at high energies. This discriminating character can be explained by the lower energy of projectile. The productivity of shower particle is lower at intermediate energies compared to that at high energies. The forward-backward averaged multiplicity of black track particle and grey track particle increases with the increasing target size.
超重核的真空衰变对于验证量子电动力学至关重要，由于过去的固定靶实验中，核外电子干扰正负电子对的测量，国际上尚未观测到该现象。提出基于HIAF SRing的并束实验方案，通过238U92+在自由空间碰撞，排除了核外电子的影响。根据亮度理论，结合对交叉角度、Laslett频移和束束相互作用的分析，优化得到1.9×1024 cm-2s-1的峰值亮度，基本满足了实验需求。
Vacuum decay phenomenon of superheavy nucleus is a problem of fundamental interest to verify quantum electrodynamics. As the shell electrons interfere the detection of electron-positron pairs in the fixed target experiments in the past, it's still not corroborated. A new merging experiment scheme is proposed in this paper. The interference of shell electrons is eliminated by collisions of 238U92+ in free space. According to the luminosity theory and the analyses of crossing angle, Laslett tune shift and beam-beam interaction, an optimized peak luminosity of 1.9×1024 cm -2·s -1 is achieved. It meets the requirements of merging experiment essentially.
研究了能量在100到300 keV区间的低能宽幅电子束从真空引出到空气中的特性。利用EGS5程序模拟了电子束穿过不同厚度钛箔后，在空气中距离钛箔5~10 cm距离处的能量损失、束流损失和束流分布均匀性等。模拟结果显示，对于低能电子，钛箔厚度应该在10 μm左右为宜，其透射率与能量直接相关，在距离钛箔5 cm的位置，电子束的分布不均匀度低于±2%，优于工业应用±10%的标准（特殊情况下要求为5%），完全满足工业辐照要求。
In order to investigate the characteristics of extracting low-energy electron beam from vacuum into air, EGS5 is used to simulate the energy loss, beam loss and spatial distribution uniformity at the irradiation position, which is 5~10 cm to titanium foil with different thickness. The simulation results show that the transmittance is directly related to the incent energy of low-energy electron. When the titanium foil thickness is 10 μm, the inhomogeneity about the energy beam spatial distribution is below 5% on the treatment plane 5 cm away from the titanium foil. And totally meet the industrial needs.
SSC-LINAC是为兰州重离子研究装置（HIRFL）设计的直线注入器，它将U34+离子加速到1 MeV/u注入到分离扇回旋加速器（SSC）中，为冷却储存环（CSR）提供10 MeV/u的U34+。该注入器可以将SSC引出的重离子流强提高一个量级以上。SSC-LINAC由一个RFQ（Radio Frequency Quadrupole）加速器和4个DTL（drift tube linac）组成，设计频率为53.667 MHz。RFQ工作在连续波模式，设计功率30 kW，如果不能有效地冷却，高频电流在电极表面产生的热量会使RFQ的腔壁和电极发生形变，从而导致腔体频率的漂移以及加速和聚焦电场的改变。因此，为了保证连续波工作的RFQ加速器稳定运行，对水冷模式和通道设计提出了很高的要求。作者用有限元软件ANSYS对RFQ进行高频电磁场、温度场、结构应力的耦合分析，验证了冷却方案设计的可行性和可靠性。
Heavy Ion Research Facility at Lanzhou(HIRFL) consists of SFC, SSC, CSRm and CSRe. A new linac injector, which will increase U34+ to 1 MeV/u, is designed for SSC to increase the beam intensity to ten times higher. The new injector, whose frequency is 53.667 MHz, is composed by a RFQ (Radio Frequency Quadrupole) cavity and four DTL(Drift Tube Linac) cavities. The RFQ cavity, whose RF power is 30 kW, is operated at CW(continuous wave) mode. The heat produced by HF (high frequency) electromagnetic will cause deformation of RFQ structure, lead to the resonant frequency shift, and reduce the focusing efficiency of the cavity. An efficient cooling system is necessary to ensure that the RFQ cavity can stably be operated at the nominal frequency. A detailed multi-physics field coupling analysis of RFQ has been finished with 3D finite elements software ANSYS. The result of the analysis shows that the water cooling system can cool the RFQ cavity fully and keep the frequency drift be in a acceptable level.
为了能很好地鉴别碎片质量，建立一个好的飞行时间测量方法是十分必要的。阐述了建立用于裂变碎片质量测量的微通道板（MCP）和金硅面垒探测器（SBD）飞行时间探测系统。对于80 μg/cm2厚的碳膜，241Am的α粒子的探测效率约为39%，252Cf（sf）裂变碎片的探测效率约为98%。在动能为78 MeV条件下，对252Cf（sf）重裂变碎片（138~148 u）得到的时间分辨为（224：1±6：1）ps；在动能为102 MeV条件下，对252Cf（sf）轻裂变碎片（101~111 u），得到的时间分辨为（154：5±5：8）ps。
In order to separate the mass number of fragments in the fission reactions, it is essential to develop a good time-of-flight (TOF) method. The purpose of this article is to set up a TOF detector system including a microchannel plate (MCP) and a Au-Si surface-barrier detector (SBD). The TOF system shows a detection efficiency of 39% for α-particles released from 241Am and 98% for fragments in the spontaneous fission of 252Cf. The experimental results show that the time resolutions of (224:1±6:1) ps for the heavy fragments (Ek=78 MeV, AH=138~148 u) and (154:5±5:8) ps for the light fragments (Ek=102 MeV, AL=101~111 u) can be obtained.
介绍了兰州重离子加速器冷却储存环（HIRFL-CSR）外靶实验中时间起点探测器（T0）的前端电子学原型模块的设计与测试。探索了基于过阈时间法和专用集成电路NINO芯片进行多气隙电阻板室探测器信号读出的模拟前端电路的设计技术，并实际完成了原型电子学模块的设计。此模块共集成6个测量通道，可以进行前沿甄别及电荷时间变换。目前已经在实验室条件下完成了各项电子学性能测试，包括不同甄别阈值下的时间精度测试以及不同输入信号幅度下的输出脉宽测试。测试结果表明，在100 fC至2 pC的动态范围内，此模块时间精度好于20 ps，满足应用需求，这也为进一步的电子学系统设计做好了准备。
A prototype front end electronics (FEE) module is designed for the T0 detector in the External Experiment in CSR (Cooling Storage Ring) of HIRFL (Heavy Ion Research Facility in Lanzhou). Based on the Time-Over-Threshold method and NINO ASIC, a total of 6 channels are integrated in the module, and both high precision leading edge discrimination and Charge-to-Time Conversion can be achieved, which satisfies the readout requirement of MRPC (Multi-gap Resistive Plate Chamber). A series of tests were also conducted in the laboratory, including time precision tests with different thresholds and output pulse width tests with different input signal amplitudes. Test results indicate that this prototype module functions well, and the time precision is better than 20 ps in the dynamic range from 100 fC to 2 pC, which is beyond application requirement. Through this work, preparation is made for the future readout system design.
在兰州重离子加速器冷却储存环（HIRFL-CSR）的外靶终端（ETF），设计建造了一套多层CsI（Tl）望远镜探测器，用于对轻质量带电粒子的鉴别。这套探测器由7层CsI（Tl）晶体组成，每一层晶体光输出信号由4个光电倍增管分别在晶体4角读出。由于CsI（Tl）晶体对于重离子的响应是非线性的，且与入射离子的种类有关，这些因素使得对这台探测器的能量刻度需要做专门的研究。利用RIBLL2提供的能量在200 s~300 MeV/u的次级束流对探测器进行了测试，并针对第一片CsI（Tl）晶体的光输出以及所有CsI（Tl）晶体光输出的和的刻度方法分别进行了探索。在此能区下，第一片CsI（Tl）晶体猝灭现象可以近似忽略，即光输出与能量沉积近似呈线性。对于所有晶体光输出的和，利用一个经验公式对其进行刻度，利用这种刻度方法计算得到的光输出的值与实验测量值之间的差别小于5%。
A multi-layer CsI(Tl) telescope has been designed and constructed at External Target in Facility (ETF) terminal of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), and is used for identifying light charged particles. The detector consists of seven layers of CsI(Tl) crystals, and the signals of each crystal are read out by four photomultipliers at the corners. Since the response of the CsI(Tl) crystal to the heavy ions is non-linear and also depends on the species of the incident ions, the energy calibration method of the telescope must be carefully studied. With the help of the secondary beams selected by RIBLL2 in the energy ranges from 200 to 300 MeV/u, the telescope has been tested and the energy calibration method for the first-layer crystal together with the whole telescope has been investigated. In this energy region, the quench effect in the first-layer crystal can be neglected and a linear expression can be used to represent the relation between the light output and the energy deposition in the crystal. To the total light output of the telescope, an empirical formula is used for the energy calibration. The difference between the calculated results and the experiment data is globally less than 5%.
暗物质粒子探测卫星（Dark Matter Particle Explorer，DAMPE）的塑闪阵列探测器（Plastic Scintillator Detector，PSD）需要实现高能e/γ粒子的鉴别功能以及对Z=1~20的宇宙线重离子的电荷测量功能。它使用光电倍增管作为读出器件，并从打拿极5和打拿极8同时引出信号来增大读出动态范围。基于该设计方案的探测单元模块在兰州重离子加速器冷却储存环（HIRFL-CSR）上的外靶终端（ETF）进行了束流测试实验。实验得到了PSD单元条在中能轻核区（Z≤8）的能量响应，并证明了单元条的衰减长度与入射粒子种类无关。通过将实验结果外推至高能重核区，同时结合衰减长度、入射角度和能量涨落等因素，可以估算出PSD探测单元模块输出信号幅度的动态范围。结果显示，该范围在PSD前端电子学模块的线性工作区间内，从而验证了PSD大动态范围读出方案设计的合理性。
The Plastic Scintillator Detector (PSD) of DArk Matter Particle Explorer (DAMPE) aims for high energy e/γ identification and charge measurement for cosmic-ray ions from Z=1~20. It adopts photomultiplier tube as the readout device and extracts signals from both dynode5 and dynode8 to enlarge the readout dynamic range. A beam test on a PSD detector unit based this design has been carried out at the External Target Facility (ETF) terminal of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The detector response to light nuclei (Z≤8) at the medium energy scale was extracted and the attenuation length was proved to be irrelevant with the impinging nuclei species. By extrapolating the result to heavy nuclei at the high energy scale and taking into account light attenuation, energy fluctuation and imping angle, the dynamic range of the output signal of PSD detector unit was estimated. The range is well within the linear range of the front-end electronics of PSD, thus verifies the large dynamic range readout design of PSD.
利用蒙特卡罗程序MCNPX模拟计算了纯聚乙烯球和加入辅助材料的聚乙烯球对不同能量中子的响应函数曲线，使用计算出来的响应函数作为U-M-G软件解谱所需输入文件。研发了一套专门为此多球谱仪进行数据采集的放大甄别一体化电路，该电路可为SP9管提供900 V的工作高压，甄别阈设为0.5 V，总的放大倍数为200倍。使用研制的Bonner球谱仪对已知源强的Pu-Be中子源进行能谱测量，测量结果显示解出的能谱数据与实际Pu-Be源中子能谱较为符合，实验结果验证了该套多球谱仪可用于测量Pu-Be能区的中子谱。
Neutron response of Bonner spheres which include pure polyethylene and polyethylene with auxiliary material was calculated with Monte Carlo code MCNPx, the calculated response was used as the input le of U-M-G code for neutronspectrum unfolding. A special screening of ampli cation integrated circuits was developed, which can provides high voltage 900 V working for the SP9 tube, the screening threshold is set to 0.5 V and total magni cation is 200. Neutron energy spectrum of a Pu-Be source were measured with the developed Bonner spheres spectrometer,good agreement was found in the measured result of the spectrum datasolutionand the real spectrum, which indicated that the multi-sphere spectrometer was reliable in the neutron measurement at energy region of Pu-Be neutron source.
微束装置可以为生命科学研究提供微米定位、剂量特定的电离辐射，在生物体内的电离辐射靶物质及其敏感度、靶物质的损伤及修复机制研究中具有独特的作用。概述了生物微束装置和实验技术的发展及其在低剂量辐射效应、旁观者效应、信号传导研究中的主要应用；介绍了中国科学院近代物理研究所（IMP）重离子微束装置，该装置可以提供能量7~ 80 MeV/u、传能线密度为30~ 3000 keV/μm的重离子微束，实现了活细胞辐照和在线观察、小鼠定位辐照的实验技术；利用IMP微束装置在重离子诱导旁效应实验、小鼠下丘脑重离子辐照效应和DNA损伤快速修复动态等方面取得了一些实验成果。
The microbeam facility can provide micrometer scale localized and predefined ionizing radiation in the life science study, and the microbeam techniques play a unique role in determining the target substances of ionizing radiation, as well as in the study of radiation sensitivity, mechanisms of radiation damage response and repair. This paper summarizes the technical developments of biological microbeam facilities and their applications in the studies of low-dose radiation effect, bystander effect and cellular signaling. This paper also introduces the recent developments at the heavy-ion microbeam facility in the Institute of Modern Physics (IMP), which can provide heavy ion microbeam irradiation with energy of 7~80 MeV/u and LET of 30~3000 keV/μm. The facility can perform radiobiological irradiation and online investigation in living cells and mice, including bystander effect study, sleeping system influence after irradiation to mice hypothalamus and the recruitment dynamics of XRCC1 protein.
BTG1, an important anti-proliferative gene, plays critical roles in cellular response to stresses, including ionizing radiation (IR). However, the long term expression of BTG1 induced by IR and its upstream/downstream signal pathways have not been elucidated clearly until now. The qRT-PCR results showed that the expression level of BTG1 in 786-O cells was rapidly elevated by IR in a short time, and then decreased slowly. In addition, upregulation or downregulation by transfection of BTG1 overexpression vector or siRNA could significantly affect the carbon ion radiation-induced genomic instability. Further study indicated that IRinduced BTG1 expression may be regulated by NF-B-mediated activation of SKA2 indirectly; On the other hand, expression of BTG1 may cause epigenetic changes by activating PRMT1, and subsequently influence the genomic stability, cell cycle regulation and apoptosis.
筛选低Cd积累水稻品种是控制稻米Cd含量的最直接有效的办法之一。本研究对重离子辐照的中籼9311（Oryza sativa L）后代，利用石墨炉原子吸收光谱法检测，对曝露在不同Cd含量（含Cd量为19.8 mg·kg-1镉池和含Cd量为2.721 mg·kg-1的污染农田）中进行M2代Cd低吸收突变单株筛选，研究重离子辐照水稻籽粒Cd吸收的突变率以及比较不同Cd含量曝露下的筛选效率。结果显示：重离子辐照可以诱发水稻籽粒Cd积累量的变异，其突变频率为3：398%±0：009（P<0：05）；初筛获得78株籽粒较WT Cd吸收差异显著的突变体，进一步对其种植，分析M3代籽粒Cd含量。结果表明，重离子辐照诱变水稻突变体突变率高，遗传稳定，高Cd含量曝露下筛选效率更高，突变体水稻籽粒中Cd的积累存在着明显的差异，产生Cd积累差异的基因型丰富；相关性分析表明，M2代和M3代糙米中Cd含量存在显著相关性r=0：8210（P<0：01），M3代获得23株遗传性良好且Cd含量差异显著的突变体水稻，其中Cd含量低于国家标准0.2 mg·kg-1突变体3株。表明筛选出的水稻突变体，在吸收转运Cd的过程中，存在差异且能稳定遗传，可供进一步研究培育籽粒Cd低积累的水稻品种。
Screening low-cadmium rice cultivar is the most directly and effective way to control cadmium content in rice grain. We screened low-cadmium rice mutant of M2 generation exposed in different Cd concentration (the pool contaminated with 19.8 mg Cd·kg-1 and the paddy field contaminated with 2.721 mg Cd·kg-1) from rice mutants(9311, Oryza sativa L) induced by 12C6+ ion beam, and explored the mutation rate of 12C6+ ion beam irradiation and the screening efficiency of different Cd concentration exposed, all of the detections were carried out by Graphite Furnace Atomic Absorption Spectrum(GFAAS). The results showed that the mutation rate is 3:398%±0:009(P<0:05) and high Cd concentration exposed has more efficiency in screening low-Cd rice mutant. Correlation analysis show significant correlation of Cd in rice grain between M2 and M3 generations, r=0:8210(P<0:01); We obtained 23 mutant strains with significant Cd concentration difference and they had a great genetic stability. Among them, three strains' Cd concentrations were lower than the national standard (0.2 mg·kg-1). They can used for further study on cultivating new rice varieties of low Cd accumulation in rice gain.
本研究以拟南芥（Columbia野生型）干种子为材料，利用兰州重离子研究装置（HIRFL）产生的碳离子束对材料进行辐射处理，统计其存活率、根长、下胚轴长及每果荚种子数，以探讨不同传能线密度（Linear Energy Transfer，LET）的碳离子束辐照对拟南芥当代损伤效应的影响。结果表明，在相同LET辐射条件下，随着辐射剂量的增大，拟南芥的存活率、根长、下胚轴长度、每果荚种子数都呈现下降趋势。在相同剂量不同LET辐射处理情况下，随着LET的增大，存活率、根长、下胚轴长、每果荚种子数都显著下降，可见高LET辐射严重抑制了拟南芥的生长和发育。研究表明，当LET为50 keV/μm时，碳离子束辐射拟南芥干种子对应的最佳诱变剂量为200 Gy，为后续开展碳离子束辐射的诱变效率研究奠定了前期基础。
Aimed to study the biological effects of carbon ion beams with different linear energy transfer (LET) values provided by Heavy Ion Research Facility in Lanzhou (HIRFL), dry seeds of Arabidopsis thaliana (Columbia-WT) were irradiated and a series of biological effects of postembryonic development, such as survival rate, primary root length, hypocotyls length and number of seeds per silique, were investigated. The results showed that, under the radiation condition of the same LET value, the survival rate, root length, hypocotyls length and number of seeds per silique were decreased with the increasing dose. In addition, under the radiation conditions with different LET values, but same dose, the extent of the decline of the survival rate, root length, hypocotyls length and number of seeds per silique were reinforced with the increasing LET. It was also found that high LET radiations inhibited the subsequent growth and development of Arabidopsis thaliana severely. In brief, it was suggested that the optimum dose of carbon ion beam with 50 keV/μm value on Arabidopsis thaliana dry seeds was 200 Gy. This research complemented the preliminary theoretical foundation for the comparative study of the highest mutation efficiency of carbon ion beam irradiations at IMP, CAS(Institute of Modern Physics, Chinese Academy of Sciences).
利用马尔可夫链蒙特卡罗（Markov Chain Monte Carlo，MCMC）方法估计Logistic回归模型中的参数，就是要构造一个以参数的后验分布为其平稳分布的非周期不可约的马尔可夫链，然后用该平稳分布中抽出的样本点计算蒙特卡罗积分。上述理论方法可以解决实验样本数据由于存在定和约束和多重共线性、在进行经典的logistic回归建模时的困难问题。基于此方法，研究了丁酸梭菌株对于给定辐照区间剂量的应答趋势，用模型挖掘数据所隐含的内在信息并导出了Logistic回归模型参数的贝叶斯框架下的50%，90%，95%和99%的置信区间。结果表明，运用Logistic与马尔可夫链耦合模型在有关给定辐射剂量对于微生物作用效果问题的logistic回归建模中具有较大的科学性与很好的使用性，从而可以为辐照诱变处理微生物制定辐照剂量区提供理论支持和回归技术借鉴。
Using the Markov Chain Monte-Carlo method to estimate the parameters in the Logistic regression model, we constructed a non-periodic irreducible Markov Chain with the posterior distribution of the parameters as stationary distribution, and then used the sample points extracted from the stationary distribution to calculate the Monte-Carlo integral. The above theoretical method can solve the difficult problem of classical logistic regression modeling because of the existence and limitation of the experimental sample data and the multicollinearity. In the classical regression setup with a continuous response, the predicted values can range over all real numbers. Therefore, a different modelling technique is needed. In this work, the results describe in detail a previously unknown lethality trend following 12C6+ heavy-ion irradiation of Clostridium tyrobutyricum. By Markov Chain Monte-Carlo can calculate the model fit for a randomly selected subset of the chain and calculate the predictive envelope of the model. The grey areas in the plot correspond to 50%, 90%, 95%, and 99% posterior regions. More importantly, although this study focused on the use of the method in heavy-ion irradiation of microbial, its results are broadly applicable.
Excitation temperature of fragmenting atomic clusters can been extracted from the initial kinetic energies of ionic products. To improve the accuracy of the temperature measurements, we have designed an ionic velocity map imaging spectrometer with high kinetic energy resolution. Firstly, based on the simulations using Simion8.0 software, the high resolution is obtained by adjusting the structure of the electrostatic lenses and collimation of molecular beam. According to theoretical analysis, it is proved that the spectrometer has a well defined kinetic energy resolution. Then, we have studied the delay ionization processes of C60 induced by nanosecond laser. A series of narrowed two-dimensional time-sliced velocity images of the C60+ with increasing the delayed time were recorded. Analysis revealed that Coulomb force between C60+ clusters in same laser shots will broadening the transverse distribution of 2D image. Considering the influence of Coulomb force on initial kinetic energy of C60+ clusters, the high resolution has been proved by analysing the negative relationship between Coulomb force and delayed time. It indicates that the establishment of the spectrometer builds up a good basis for next experiments on the studies for molecular thermodynamics in atomic clusters.
利用反应显微成像谱仪，研究了50 keV/u Ne8+碰撞CO转移电离反应中生成的CO2+碎裂过程。通过重构分子离子爆炸碎片C+和O+的三维动量，获得了质心系中CO2+碎裂过程中释放的动能（KER）。在KER谱中发现了来自亚稳态1Σ+，1Π，3Π解离的峰、3Σ+态解离的峰和1Σ（II）+态解离的峰，同时发现了排斥态3Σ-的贡献。在3Σ-态解离的分子轴取向分布中，首次观测到CO2+解离的分子轴取向效应。
The fragmentations of CO2+ are studied in transfer ionization processes of 50 keV/u Ne8+ impact on CO with reaction microscopes. The 3D momenta of C+ and O+ were measured, and the kinetic energy release (KER) of dissociative(CO2+) was obtained accordingly. The peaks resulted from the metastable states of 1Σ+, 1Π and 3Π, of 3Σ+, and of 1Σ(II)+ are identified in KER spectrum. Meanwhile, the repulsive state of 3Σ- was also observed, which forms a broad peak lying between the peaks of 3Σ+ and 1Σ(II)+. In the CO2+ dissociations from 3Σ- state, the orientation effect of CO molecular axis was observed for the first time.
175Lu（n；2n）174m，gLu（n；2n）173Lu反应在高能中子通量监测中具有重要作用，其产物的放射性活度通常用HPGe探测器测量，这就需要174m，gLu和173Lu的半衰期和γ射线发射率等衰变数据必须准确无误。在主要的评价核数据库中，只有ENDF/B 7.1和JEFF 3.1.1数据库给出了173Lu和174Lu的半衰期和γ射线的发射几率等衰变数据，其中173Lu的射线发射几率ENDF/B 7.1库比JEFF 3.1.1库总体偏高，其他评价数据两个数据库非常一致。在中国原子能研究院的串列加速器上用20 MeV质子辐照金属Yb靶生产了含有173Lu，174m，gLu的放射性溶液，用激光共振电离质谱（LRIMS）和热表面电离质谱（TIMS）两种同位素稀释法测定了该溶液中173Lu和174m，gLu核素浓度，然后制备测量源在HPGe探测器上进行了近7年的跟踪测量，发现173Lu的半衰期为1.45 a，比目前评价的数据1.37 a高6.1%，636.1 keV射线发射几率的偏差最大，比ENDF/B 7.1的评价数据偏高7%。174gLu半衰期的测量结果3.37 a175Lu（n；2n）174m，gLu（n；2n）173Lu反应在高能中子通量监测中具有重要作用，其产物的放射性活度通常用HPGe探测器测量，这就需要174m，gLu和173Lu的半衰期和γ射线发射率等衰变数据必须准确无误。在主要的评价核数据库中，只有ENDF/B 7.1和JEFF 3.1.1数据库给出了173Lu和174Lu的半衰期和射线的发射几率等衰变数据，其中173Lu的射线发射几率ENDF/B 7.1库比JEFF 3.1.1库总体偏高，其他评价数据两个数据库非常一致。在中国原子能研究院的串列加速器上用20 MeV质子辐照金属Yb靶生产了含有173Lu，174m，gLu的放射性溶液，用激光共振电离质谱（LRIMS）和热表面电离质谱（TIMS）两种同位素稀释法测定了该溶液中173Lu和174m，gLu核素浓度，然后制备测量源在HPGe探测器上进行了近7年的跟踪测量，发现173Lu的半衰期为1.45 a，比目前评价的数据1.37 a高6.1%，636.1 keV γ射线发射几率的偏差最大，比ENDF/B 7.1的评价数据偏高7%。174gLu半衰期的测量结果3.37 a，比评价数据3.31 a高约1.8%，174gLu 76.5 keV和1 241.8 keV γ射线的发射几率比ENDF/B 7.1的评价数据分别低1.87%和12.8%。
175Lu(n,2n)174m,gLu(n,2n)173Lu are important neutron reactions to monitor the high energy neutron fluxes and the residual nuclei, 174m,gLu and 173Lu, are usually measured by a HPGe spectrometer conveniently so that the decay data such as half lives and gamma-ray emission probabilities of 174m,gLu and 173Lu must be accurate. There are evaluated decay data only in ENDF/B 7.1 and JEFF 3.1.1 among the major evaluated nuclear data libraries, where the most data are almost same besides the gamma-ray emission probabilities of 173Lu are higher in ENDF/B 7.1 than that in JEFF 3.1.1. Yb metal as a target was irradiated by 20 MeV proton beams on a tandem accelerator in CIAE to produce 174m,gLu and 173Lu, and 176Lu isotopic dilution methods based upon a laser resonance ionization mass spectrometer (LRIMS) and a thermal surface ionization mass spectrometer (TIMS) were employed to determine the numbers of nuclides of 174Lu and 173Lu in a solution containing the irradiated target. Several radioactive sources made from the solution had been measured by a HPGe detector during the past 7 years and the peak intensities of the characteristic gamma-rays from 174gLu and 173Lu were analyzed to determine the half lives and gamma-ray emission probabilities. According to the measurements, the half life of 173Lu is 1.45 a, which is about 6.1% longer than the evaluated 1.37 a, and the gamma-ray emission probabilities of 173Lu is also different from the evaluated data, especially the emission probability of 636.1 keV gamma-ray of 173Lu is 7% higher than the value in ENDF/B 7.1. The half life of 174gLu is 3.37 a, about 1.8% longer than the evaluated 3.31 a, and the emission probabilities of 76.5 keV and 1 241.8 keV gamma-rays of 174Lu are 1.87% and 12.8% lower than the evaluated data in ENDF/B 7.1, respectively.