2010年 第27卷 第1期
简要评述了中高能核物理中核子核子（NN）碰撞的国际研究现状, 期望对兰州重离子加速器冷却存储环（HIRFL-CSR）的物理工作有益。 文中主要涉及近年来短程核力研究进展与存在的困难, 及与STAR和PHENIX高能重离子实验新进展相关的若干NN两体碰撞基本问题等, 特别关注奇异性产生与重味产生方面的NN碰撞物理, 以便更好地认识中高能NN碰撞研究的重要性。Some topics on nucleonnucleon(NN) collisions in medium and high energy nuclear physics are reviewed with emphasis on those which are expected to be relevant at the HIRFLCSR Facility. It is mainly concerned with the description of shortrange NN nuclear force， the recent results from STAR and PHENIX experiments in relativistic collisions of nuclei from each other，addressing questions about the role of NN collisions at highenergy，especially for strangeness production and heavy flavor production. Recent progress and some unresolved issues are also concerned. We expect that the results of the present work will lead to a better understanding on the importance of NN collisions at medium and highenergy.
提出了一种夸克胶子等离子体中的喷注光子转换机制。 对于热光子而言， 在热夸克胶子媒介中的喷注光子转换是一个非常重要的热光子来源。 喷注可以通过次级康普顿散射和湮灭过程来实现喷注光子转换。 此外， 还考虑了在快光子产生过程中起重要修正作用的胶子光子贡献， 其中，核遮蔽效应和同位旋效应也被引入到了部分子模型中。We develop a jetphoton conversion mechanism in the expanding quark gluon plasma. The jetphoton conversion in hot quarkgluon medium is a vital source of the thermal photon production. The jet converts into photons via the secondary Compton and annihilation processes in the quarkgluon plasma. The gluonphotons are also considered in the calculation of prompt photons which includes the effect of the shadowing and isospin of nucleus. We find that the prompt gluonphotons are also an important modification to prompt photons.
核-核碰撞可以简单看成核子\|核子碰撞， 每一核子-核子碰撞产生的源可用经典流表示。对于时空函数的经典流系综， 当源部分相干时， 全同两粒子玻色-爱因斯坦关联函数公式应包含混沌和相干项。根据蒙特卡罗的模拟计算思想， 由混沌源2π关联函数的模拟计算出发， 得到部分相干源关联函数的模拟计算方法。 在相对动量q的out和side方向上， 对部分相干源关联函数进行蒙特卡罗模拟计算， 计算得到源的半径Rout在误差范围内近似等于Rside。Nucleus-nucleus collisions are simply regarded as sum of nucleon-nucleon collisions. Particle sources produced by nucleon\|nucleon collisions are treated as classical current. For the classical current formalism ensemble of space-time function there are two terms in two identical particle Bose-Einstein correlation function when sources are partially coherent and one is called coherent term, the other is chaotic one. According to Monte Carlo simulating theory, the algorithm for calculating correlation function of partially coherent sources is derived by generalizing chaotic one. The correlation function of partially coherent sources is simulated by this method at out and side direction of relative momentum, and the out radius of sources from the fitted result is approximately equal to the side one within the error range
在利用TeV能区宇宙射线数值模拟数据研究朝前区强子相互作用时, 需要足够多的低空簇射事例样本。提出了可以通过降低FIXCHI（宇宙射线第一次相互作用高度）来提高高能宇宙射线数值模拟效率，但对相应的能谱指数进行标定是必要的。以1 TeV处直达概率为标准， 得到各能区的能谱强度， 并采用将能谱强度与能量进行线性拟合， 以标定能谱指数的方法， 使宇宙射线数值模拟的效率及准确率都大大提高。 In the study of hadronic interaction in the forward region by the simulation of cosmic ray, it is necessary to simulate large numbers of cosmic ray events with low first interaction height. We confirmed that by reducing the FIXCHI the efficiency of cosmic ray simulation can be improved. But the calibration for energy slope is needed. We got the energy slope based on the probability of direct arrived events with energy of 1 TeV, and fitted the intensity of spectrum with energy to make certain the energy slope of high energy cosmic ray. By this way, the efficiency and precision of cosmic ray simulation is greatly improved.
对149Sm(27Al, 4n)172Re反应产生的172Re在束γ的实验数据进行了重新分析， 新发现了可归属于172Re的3个转动带， 由此建立了由6个转动带构成的172Re高自旋态能级纲图。依据相邻核的带结构知识和推转壳模型分析方法， 对新发现的3个转动带的准粒子组态进行了指定， 讨论了它们的转动特征。We have reanalyzed the experimental data of inbeam γ spectroscopy for 172Re via the 149Sm(27Al, 4n)172Re reaction. Three rotational bands have been newly found and assigned to 172Re. A new level scheme of 172Re, consisting of 6 bands, is thus presented. Based on the existing knowlegde from the neighboring nuclei and the cranked shell model, the quasiparticle configurtions have been assigned to the 3 newly observed bands and their structure properties have been dicussed.
基于球形与轴对称形变的相对论平均场（Relativistic Mean Field， 简称RMF）理论模型， 分别计算了Zr同位素链的基态总能量， 并根据其差值提取了形变修正能后发现， Zr同位素链丰中子区的核具有大的长椭形变， 对应的形变修正能可达到10 MeV。 利用RMF理论计算的基态能量， 在扣除液滴模型计算的结合能后， 得到了Zr同位素链的壳修正能。 通过对壳修正能的分析后发现， 形变使N=50壳效应显著减弱。 特别是在丰中子区， 大形变导致了N=50壳结构的消失。 The total binding energy of nuclei for Zr isotopic chain is calculated by the spherical and axial deformed relativistic meanfield(RMF) theory respectively, and the energy contribution due to the deformation(i.e., deformation correction energy) is extracted. It is found that the neutronrich nuclei in the isotopic chain have large prolate deformation, and corresponding deformation correction energy can be up to 10 MeV. The shell correction energy is obtained by the difference between the binding energies calculated by the liquid model and those by the RMF calculations. Detailed analysis indicates that the deformation weakens the shell effect of N=50 remarkably. Especially for the neutronrich nuclei, large deformation leads to disappearance of the N=50 shell structure.
高效率的电子冷却过程， 要求电子束与离子束位置平行且重叠。 为了同时测量电子束与离子束的位置， 在HIRFLCSR电子冷却装置上研发了以容性圆筒形极板为感应电极的束流位置探测系统。 系统测量束流通过探针时产生的脉冲感应信号， 并进行傅里叶变换得到频谱信号， 分析4个不同电极上频谱信号强度获取束流的位置信息。 测量结果表明， 该束流位置探测系统测量准确， 为定量研究储存环离子累积和电子冷却过程与两种束流相对位置及角度的依赖关系提供了条件。
The efficient electron cooling requires that the ion beam and electron beam are parallel and overlapped. In order to measure the positions of ion beam and electron beam simultaneously， a beam position monitor system is developed for the HIRFL-CSR electron cooler device， which probe consists of four capacitive cylinder linearcut poles. One can get the both beam positions from the picking up signals of four poles by using Fourier transform(FFT) method. The measurement results show that the beam position monitor system is accurate. This system is suitable for investigating the relation between electron cooling processing and the angle of ion beam and electron beam.
近些年来，使用锯齿波直接形成的方法建造非谐振型聚束器在国内及国际均得到了广泛的应用。 由于电子技术及机械加工工艺的飞速发展和更高功率电子管的出现， 可以设计出更高指标的聚束器，进而可以有效提高束线的匹配效率及运行稳定度。 对兰州重离子加速器源束线新的高电压锯齿波聚束器的研制进行了详细阐述， 由于该聚束器具有目前国际同类型设备中最高的电压、 频率以及相对苛刻的现场条件限制， 故还对设计中所涉及的工程实施方案进行了有效补充和完善。
The method which builds a buncher with nonresonant cavity through the direct production of sawtooth wave has already been applied commonly to accelerator technologies all over the world. Recently, with the rapid development of electronic and mechanical manufacture technology during the last few decades, it leads to develop a sawtooth buncher easily, furthermore, it can improve match efficiency and operation stability in HIRFL at IMP. It has been concluded that the design can be applied to more sophisticated specification according to this method and the measurement of building higher voltage buncher is feasible. At last, we complement critical points involved implementation of this project and makes it work efficiently because of the highest demand and more rigorous installation limitation of this new buncher throughout the world.
动力学孔径对环形加速器, 尤其是现代的储存环, 起着越来越重要的作用。采用MAD程序研究了兰州重离子加速器实验环（CSRe）的动力学孔径。通过对比几种情况下的模拟结果， 发现六极铁和二极铁的高阶场对束流的动力学孔径影响较大， 使CSRe的动力学孔径减小， 但减小后的动力学孔径也远大于该环的物理孔径。因此， 束流可以长期、 稳定的存在。Dynamic aperture(DA) is playing a more and more important role in circular accelerators, especially in the modern storage rings. In this paper, the DA of CSRe is analyzed by MAD program. Comparing the DA under various assumptions, we find that the multipole errors in dipoles or quadrupoles, and the sextupoles which bring strong nonlinearities, and limit the DA of CSRe. Fortunately, the DA is larger than the physical aperture in all the cases, and that is large enough to satisfy the high precision physical experimental request.
介绍了一种正电子发射断层成像术实时查找表电路.该电路接收符合电路输出的位置信号和能量信号， 用查表的方法完成重心法中的除法运算，然后再第二次查表得到该γ光子所入射到的晶格的离散化坐标值和能量阈值，并完成能量甄别以剔除部分散射事件。 此外，该电路还结合了呼吸门控和心电门控功能。 查找表存储在flash器件中，由CPLD控制读写。本设计的特点是利用硬件电路来完成查找表功能，效率更高，每次事件的查表寻址的延迟时间小于100 ns， 并且可以在线更新查找表的内容，使用方便。另外，还说明了用CPLD来读写NOR flash的方法，以及该电路与系统中其它模块间的数据通信方法。
A new design of lookuptable(LUT) electronics for a small animal positron emission tomography(PET) system is proposed. Position and energy signals for a coincidence event are generated in a coincidence circuit board and sent to the LUT board， in which the centroid of this event is calculated by the LUT approach. The centroid is used as an index of the crystal element. Corresponding coordinates and energy threshold of this crystal are obtained from the other tables， and the scattered events are rejected. Interfaces for receiving respiratory and electrocardiac gate signals are designed for future use. All the lookup tables are stored in NOR flash memory which is controlled by a Complex Programmable Logic Device. The LUT board communicates with PC through Ethernet board. The advantage of this specific hardware design is that the LUT operation can be performed in a more efficient way， with a <100 ns time delay. The paper also describes the operation of the flashmemory with a CPLD， and the data flow between this LUT and other modules in our PET system.
多阳极位置灵敏光电倍增管（PSPMT）被广泛地用来开发高分辨的小型γ相机模块。探讨了PSPMT的位置读出电路的简化设计研究， 并针对日本滨松的H8500型多阳极PSPMT， 设计和开发了离散位置读出电路（DPC）和均衡电荷分配电路（SCDC）两种简化的位置读出电路， 并在SCDC中加入了局域重心（TCOG）的定位方法， 进一步地优化读出电路的简化设计。初步的实验测试结果表明， SCDC结合TCOG定位法， 能显著地改善探测器的定位非线性及压缩效应， 扩展有效的成像视野（FOV）， 比DPC方法的有效视野增大了约20%。The multianode position sensitive photomultiplier tube(PSPMT) has been used for the development of highresolution γ camera module. This study is aimed to investigate the simplified readout design for the multianode flat panel PSPMT. Based on the Hamamatsu H8500 PSPMT with 64 multianodes, we designed and developed two simplified readout circuits, discretized positioning circuit(DPC) and symmetric charge division circuit(SCDC). The truncated center of gravity(TCOG) positioning method was used to optimize the readout signal processing and then further reduce the readout channels by a resistor chain. The preliminary results show that the SCDC readout with the TCOG could significantly reduce the nonlinearity of positioning and improve the effective fieldofview of the detector by about 20% as compared to the DPC readout.
研究了多种包装材料和包装工艺对钨酸铅(PbWO4)晶体光输出和能量分辨的影响， 测量结果与基于GEANT4的模拟结果符合很好， 并由此确定了晶体的最佳包装方法。
The light output and energy resolution of PbWO4 crystal are studied with different wrapping materials and methods. The Wrapping condition was optimized by analyzing the experimental data to gain higher light output and better energy resolution. A GEANT4based package has been developed to simulate the corresponding features of PbWO4 crystal, and the simulation results are consistent with the experimental data.
长寿命核素36Cl的半衰期为3.01×105 a， 广泛分布于自然界中。 加速器质谱是目前测量36Cl的最灵敏的方法。 介绍了36Cl的样品制备及加速器质谱测量方法， 重点描述了基于小型化加速器质谱发展起来的测量36Cl的探测方法及其特点， 综述了各实验室利用36Cl在相关领域开展的工作及所取得的成果。 The distribution of longlived isotope 36Cl (T1/2=3.01×105 a) is widely spread in the world. Accelerator mass spectrometry(AMS) is presently the most sensitive method for the measurement of 36Cl. The sample preparation and AMS measurement procedure are briefly introduced. The detection methods based on the “small” AMS are also introduced, as well as their performance. The research progress on applications of 36Cl in various laboratories around the world is reviewed.
在精确放射治疗中， 精确计算楔形挡板的楔形因子是精确修正加入楔形挡板后剂量值的关键。提出了基于衰减系数法思想的改进楔形野剂量修正算法， 首先计算了楔形挡板材料的线性衰减系数， 再根据楔形挡板的实际剖面尺寸， 建立了线性拟合公式计算射线束穿过楔形挡板的实际厚度， 精确计算楔形因子， 并以AAPM55号报告提供的45°楔形挡板进行了验证。该方法在保证计算精度的同时减少了大量离轴测量数据， 减轻了物理师的负担， 可以作为一种有效的楔形挡板修正算法应用于放射治疗计划系统中。 In accuracy radiotherapy, it is difficult to calculate dose accurately during wedge fields. In this paper, an improved corrected algorithm of wedges based on the lineattenuation was proposed. The lineattenuation coefficient of wedges was calculated firstly, then the actual path of radial beam in the wedge was calculated by the “linear fitting” according to the sizes of wedges section. Finally the wedge factors could be determined accurately， and the dose could be corrected. The data of the 45 degree wedge in the report of AAPM 55 were used to make the calculation and verificaton. Using this algorithm,amount of measured data were decreased, the accuracy of calculation could be assured， and the job of physician could be reduced,so this algorithm could be applied in the treatment planning system as an effective calculation method of wedges field.
选用12C6+离子辐照诱变阿维菌素B1a产生菌ZJAV-A1， 研究其诱变效应。 实验结果表明， 12C6+离子辐照剂量50 Gy时致死率97%，正突变率最高可达到34.2%。 通过12C6+离子诱变处理，结合平板培养基及斜面培养基的正突变菌株筛选， 最终获得一株稳定性良好， 阿维菌素B1a组分产量稳定在4460—4588 μg/ml之间， 较出发菌株提高11.1%—14.7%的突变株ZJAVY1203。 Mutagenic effect on avermectin B1a producing strains of ZJAV-A1 by ion beam of 12C6+ has been investigated.The experimental results indicated that the lethality was 97% and the highest rate of orthomutation was 34.2%， when ZJAVA1 was irradiated by ion beam of 50 Gy 12C6+. After the mutagenesis processing by ion beam of 12C6+ and the screening of orthomutation strains by using plating mediums and slant cultures，the mutant ZJAV-Y1203 was obtained with theavermectin B1a yield of 4588—4460 μg/ml. Compared with the original strain， the titer was improved 11.1%—14.7%.
室温下用80 keV N离子注入ZnO薄膜样品， 注量分别为5.0×1014， 5.0×1015和5.0×1016 ions/cm2， 然后用X射线衍射和透射电镜技术对样品的结构特性进行了表征。实验结果表明， 由高度(002)择优取向的致密柱状晶构成的薄膜中， 注入5.0×1015 ions/cm2时， 观测到缺陷生成和局域无序化现象， 但薄膜总体结构仍保持柱状晶和(002)择优取向； 随着注量的增大， 晶格常数c和压应力呈增大趋势。对注入N离子对ZnO薄膜结构特性的影响机理进行了简单的讨论。ZnO thin films were implanted at the room temperature by 80 keV N-ions to 5.0×1014, 5.0×1015 or 5.0×1016 ions/cm2, the structural characteristics of the samples were investigated using X-ray diffraction(XRD) spectrometer and transmission electron microscopy(TEM). It was found that the un-implanted ZnO films are constituted of columnar crystals which are very compact and of preferred c-axis orientation. After N-ion implantation, the crystal lattice constant and the biaxial compressive stress increased with the increasing of the N-implantation dose. In the 5.0×1016 N-ions/cm2 implanted ZnO sample, a new XRD peak due to defects or N-dopants appeared. Moreover, defects and localized disordering in the 5.0×1015 N-ions/cm2 implanted ZnO films have been observed under high resolution TEM measurement. However, N-ion implantation could not change significantly the crystal structure of the ZnO films. Possible mechanism of the structural modification of ZnO films by N-ion implantation was briefly discussed.
室温下， 用94 MeV的Xe离子辐照纳米晶和非晶硅薄膜以及单晶硅样品， 辐照量分别为1.0×1011，1.0×1012 和1.0×1013 ions/cm2。 所有样品均在室温下用UV/VIS/NIR光谱仪进行检测分析。 通过对比研究了纳米晶、 非晶、 单晶硅样品的光学带隙随Xe离子辐照量的变化。 结果表明， 不同结构的硅材料中Xe离子辐照引起的光学带隙变化规律差异显著： 随着Xe离子辐照量的增加， 单晶硅的光学带隙基本不变， 非晶硅薄膜的光学带隙由初始的约1.78 eV逐渐减小到约1.54 eV， 而纳米晶硅薄膜的光学带隙则由初始的约1.50 eV快速增大至约1.81 eV， 然后再减小至约1.67 eV。 对硅材料结构影响辐照效应的机理进行了初步探讨。
Monocrystalline silicon(cSi), thin films of amorphous silicon(aSi) and nanocrystalline silicon(ncSi) were irradiated at room temperature(RT) by using 94 MeV Xeions at 1.0×1011, 1.0×1012 or 1.0×1013 Xeions/cm2, respectively. All samples were analyzed at RT by an UV/VIS/NIR spectrometer (Lambda 900, PE, Germany), and then the uariation of the optical bandgap with the irradiation fluence was investigated systematically. The results show that the optical bandgap of the silicon samples irradiates by Xeion changed dramatically with different crystalline structures. For the aSi thin films, the optical bandgap values decreased gradually from ~1.78 to ~1.54 eV with increasing Xeion irradiation fluence. For the ncSi thin films, the optical bandgap values increased sharply from ~1.50 (origin) to ~1.81 eV(Φ=1.0×1012ions/cm2), and then decreased to ~1.67 eV(Φ=1.0×1013 ions/cm2). However, there is no observable change of the optical bandgap of the cSi after Xeion irradiations. Possible mechanism on the modification of the silicon thin films was briefly discussed.
通过25 MeV/u 86 Kr离子辐照叠层结晶聚对苯二甲酸乙二醇酯膜（PET）， 在不同的电子能损（3.40-7.25 keV/nm）和离子注量(5×1011----3×1012 ions/cm2)辐照条件下， 对Kr离子在PET中引起的辐照损伤效应进行了研究。借助傅里叶变换红外光谱分析，通过对样品的红外吸收峰进行扣除基底后的Lorentz拟合，分析了与主要官能团对应的吸收峰强度的变化趋势， 研究了化学结构与组分在重离子辐照下的变化规律； 利用X射线衍射光谱仪测量， 研究了Kr离子在PET潜径迹中引起的非晶化过程，并通过对吸光度和非晶化强度随离子注量的指数衰减规律的分析， 获得了不同电子能损离子辐照PET时主要官能团的损伤截面和非晶化截面及对应的潜径迹半径。
At room temperature， polyethylene terephthalate(PET) foil stacks were irradiated by 25 MeV/u Kr ions in the electronic stopping power range(3.3--7.66 keV/nm) and the fluence range from 5×1011 to 3×1012 ions/cm2. The behaviour of the main function groups with fluence and electronic stopping power were studied by using Fouriertransforminfrared(FTIR) spectroscopy， the degradation of the function group was investigated with the Lorentz fitting subtracted baseline. The amorphous processes in the latent tracks of PET were studied by Xray diffraction(XRD) measurements. The Kr ion induced degradation crosssection and amorphisation crosssections(radii) for different electronic energy loss were acquired from the experimental data(FTIR and XRD) by exponential decay function respectively.
用能量11.4 MeV/u和注量1×108 ions/cm2的197Au离子垂直辐照聚丙烯薄膜， 通过电导测量法监测温度、 硫酸浓度和重铬酸钾浓度对径迹蚀刻速率的影响，得到合适的蚀刻条件； 成功制备出孔径范围在600—1000 nm的重离子径迹聚丙烯孔膜，并用场发射扫描电镜对孔的形状及孔径大小进行了表征，对孔洞锥角的形成进行了分析，为重离子辐照技术制备锂离子电池隔膜提供了实验数据。The polypropylene membranes were irradiated by 197Au ions of energy 11.4 MeV/u and fluences 1×108 ions/cm2 at a normal incidence. Sulfuric acid and potassium dichromate solution were employed as the etchant to etch the ion tracks. The influences of the temperature and the concentration of each ingredient were systematically investigated by recording the electrical current during etching process. The nanoporous with different shapes were successfully prepared with homogenous porous of diameters from 600 nm to 1 μm. The morphology of the porous was analyzed by scanning electron microscopy(SEM). The experiment has provided a method for production of the lithiumion battery separator.
在经典物理框架内和偶极近似下， 导出了超晶格量子阱沟道辐射频率和辐射谱分布。指出了对于自发辐射谱分布， 存在一个普适的线型因子， 而粒子的最大辐射能量与相对论因子γ 有关， 且与γ3/2成正比。以正弦平方势为例进行了具体讨论。结果表明， 由于势阱深度和噪音的影响， 谐波数l只取少数几个值。超晶格量子阱沟道辐射只存在不多的几条谱线， 为进一步应用提供了可能。最后， 还给出了一种可能的实验方案， 讨论了如何利用弯晶把超晶格量子阱的沟道辐射改造为相干辐射。 In the frame of classical physics and the dipole approximation the radiation frequency and the spectral distribution are derived for the channeling radiation of a charged particle in a superlattice quantum well. It indicated that there is a linetype factor f(ξ) suited to various cases in the spontaneous radiations spectrum. Results also show that the maximum radiation energy is proportional to γ3/2 , but the relativistic effects have double effects in the spontaneous radiation of a charged particle. The case for the sinesquared potential is discussed specifically. The harmonic number can be defined as a few variable values by the effects of the potential well depth and noise. In general there is a few spectral lines in the channeling radiation spectrum for the superlattice quantum well, and possibilities are provided for further application. Finally, a possible experimental scheme is proposed, and it is discussed that how to transform the channeling radiation in the quantum well into the cohenent radiation by the bent crystal.
在p+58Ni反应的理论计算中考虑了集体态和转移反应机制， 利用大型程序MEND计算了Ein≤ 200 MeV能区6种轻粒子（n, p, α, d, t及3He）出射的能谱和双微分截面。计算结果与实验数据基本一致； 与以前的工作相比， 解释了能谱和双微分截面中出现的尖峰， 并减小了单粒子态密度修正因子ccg1(v)。
Collective state and transfer reaction are considered in this paper. The energy spectra and double differential cross sections of neutron, proton, alpha, deuteron, triton and helium\|3 emissions are calculated for p+58Ni reaction below 200 MeV with the theoretical model code MEND. The theoretical results agree with the corresponding experimental data. This work accounts for the peaks of the energy spectra and the double differential cross sections, and reduced the values of the single particle state density parameter ccg1(v).