2013年 第30卷 第1期
在强子物理研究中，3π产生的理论和实验有非常重要的意义，是目前世界上很多大型实验设备的重要研究对象。3π强子物理包含丰富的物理内容，可以作为探索低能区强相互作用的有力工具。同时，3π产生过程是寻找奇特轻介子态的主要途径之一。另外，通过研究3π产生反应道还可以寻找“失踪”共振态和重子激发态之间的级联衰变。介绍了目前国际各大高能物理实验室的3π产生过程的实验、理论研究以及分波分析技术现状，重点介绍了美国杰弗逊国家实验室（Jefferson Lab，简称JLab）的CLAS（CEBAF Large Acceptance Spectrometer）实验上的3π反应过程。最后，指出了3π强子物理研究的意义和未来的研究方向。Three pion productions off nucleon are of significance in the research of hadron physics. Meanwhile it is the subject of many big experimental apparatus in the world. Due to the variety of three pion productions, it can be applied as an effective tool to study QCD in low energy region. Three pion productions is one of the main reactions in searching light exotic meson state. Moreover, it is possible to find out the "missing" baryon resonance and the cascaded decay process between baryon excited states. We introduce present experiments and theories of three pion productions as well as the partial wave analysis technique. The emphasis is on the CLAS (CEBAF Large Acceptance Spectrometer) experiment at JLab (Jefferson Lab). In the end, we point out the significance of studying the three-pion hadron physics at JLab.
在非相对论夸克模型内，利用手征超精细相互作用，把原来对五夸克系统qqqq¯q 能谱的预言，扩展到了七夸克系统qqq(q¯q)2 的基态和轨道第一激发态能谱的计算，所使用的参数也是来自于五夸克系统。预言了最低七夸克态的能量大约是2.1 GeV，自旋-宇称是JP =1/2+或者JP =1/2-。由于在这个能区也存在一些三夸克系统和五夸克系统，所以能量在2 GeV 以上的重子激发态可能是这3 种夸克成分的混合。The low-lying energy spectra of 7-quark systems qqq(q¯q)2 is investigated with the schematic flavor-spin interaction, as an extension of the qqqq¯q five quark model. The lowest qqq(q¯q)2 state with an approximate energy 2.1 GeV and the spin-parity JP =1/2+ or JP =1/2-, has been predicted with the parameters used in the five quark system.Because of the overlap with the corresponding qqq and qqqq¯q states above 2 GeV, it is possible for the high excited baryon-resonances to have substantial qqq(q¯q)2 admixtures.
中子星的制动机制是中子星研究中的基本问题。磁偶极辐射模型给出中子星的制动指数为3，而所有观测到的中子星的制动指数都小于3，这表明中子星除磁偶极辐射之外还存在其他的转动能量损失方式。考虑中子星的转动动能损失来自：磁偶极辐射、由于单极感应引起的粒子流逃逸以及中子星和量子真空摩引起的能量损失。基于这3 种辐射机制，给出了改进后的中子星能量损失功率的计算公式和周期对时间一阶导数与周期的依赖关系。考察了6 颗中子星( J1119–6127, B1509–58, J1846–0258,B0531+21, B0540–69 和B0833–45 ) 的周期-周期一阶导数关系，制动指数、表面磁场强度以及磁倾角之间的关系。研究表明，星风效应中，真空间隙电势差为常数时磁倾角只能在有限范围内取值，而其他情况下磁倾角在0s 90°之间连续取值。The neutron stars’ braking mechanism is a fundamental problem in the study of neutron stars. The braking index exactly equal to 3 in pure magnetodipole radiation model, however, all the observed braking index of rotationpowered pulsars is less than 3. This indicates that the additional energy loss ways must exist besides the magnetodipole radiation. The magnetodipole radiation, the ejection of particle outflow and quantum vacuum friction are considered as the source of the loss of rotational kinetic energy of rotation-powered pulsars. Based on the three mechanism of loss of the energy, the relation between the period of pulsars and the first derivative of the period to time and the pulsars’ energy losing power are given. The relationship of the periods and the first derivative of the periods of six pulsars(J1119−6127,B1509−58, J1846−0258, B0531+21, B0540−69 and B0833−45) is studied. The relation between the surface magnetic field intensity and the magnetic inclination is discussed. Research shows that when the electric potential difference of vacuum gap is a constant the inclination angle is limited in a smaller range and in the other cases the inclination is the continuous value between 0∼90 degrees.
通过利用日本放射线医学综合研究所( NIRS ) 重离子医用加速器( HIMAC) 产生的束流照射国产的核-4型原子核乳胶，对500 AMeV 56Fe诱发乳胶核反应粒子产生进行了研究。讨论了500 AMeV 56Fe诱发乳胶核反应弹核碎片的多重数分布，并与其他结果进行了比较。结果表明，弹核碎片平均多重数随靶核质量的增加而增加，与入射能量无关。A stack of domestic N-4 nuclear emulsion was exposed to 56Fe ions at 500 AMeV at the HIMAC of NIRS. Particle production was investigated in 56Fe-Em interactions. The multiplicity distribution of projectile fragments was given in this paper and compared with other experimental results of heavy ion induced nuclear reactions in nuclear emulsion. The results show that the multiplicity of projectile fragments increase with the increasing target mass, and there
is no dependence on the projectile energy.
采用修正的Landau 流体力学模型，并考虑到带头粒子效应，对高能重离子碰撞末态带电粒子的赝快度分布进行了讨论。指出：带头粒子的快度分布应为高斯形式，其正规化常数为参与者数。研究表明：流体力学模型本身与BNL-RHIC-PHOBOS 合作组在(NN)½ =200 GeV 的Cu+Cu 碰撞中的实验测量符合得不是很好，只有将参与者的贡献包括在内，实验结果才能得到很好的描述。By using the revised Landau hydrodynamic model and taking into account the effect of leading particles, we discussed the pseudorapidity distributions of final charged particles in high energy heavy ion collisions. We argued that the rapidity distributions of leading particles have the Gaussian form with the normalization constant being equal to the number of participants. The investigations show that the results from the hydrodynamic model alone are not consistent with the experimental data carried out by BNL-RHIC-PHOBOS Collaboration in Cu+Cu collisions at (NN)½ = 200 GeV. Only after the contributions from leading particles are included, can the experimental measurements be described well.
ECR离子源的等离子体阻抗对其微波传输与阻抗匹配设计至关重要。在中国科学院近代物理研究所现有的2.45 GHz ECR 质子源上，对等离子体阻抗进行了测量。首先用水吸收负载代替等离子体负载测量得到了所用微波窗阻抗，然后根据质子源测量数据，推算得到了等离子体阻抗。实验结果表明，脊波导输出端阻抗与后续负载不完全匹配，等离子体阻抗随微波功率变化呈非线性。这些结果为ECR离子源过渡匹配和微波窗的设计提供了参考依据。Plasma impedance of an ECR ion source is important for microwave transmission and impedance matching design. Plasma impedance was measured indirectly with the 2.45 GHz ECR proton source at the Institute of Modern Physics, Chinese Academy of Sciences. In the test, we got microwave window mpedance by using water absorption load instead of plasma load, and the source plasma impedance was derived from the test data with the 2.45 GHz ECR proton source and microwave window impedance. The experimental results show that ridge waveguide output impedance and the subsequent load does not exactly match, plasma impedance variation is nonlinear with microwave power. The achieved
result is useful in the design of ridged waveguide and microwave window.
为了解决兰州重离子研究装置( HIRFL ) 电源控制系统中的MSC1210 控制模块在调束过程中出现的各种故障，对其主芯片程序进行了优化设计。首先介绍了控制器的各种故障现象，分析了形成原因，然后制定了详细的设计方案，最后采用了以状态机为基础的指令接收过程、带校验机制的通信方式及远程指令复位等方法进行程序优化。实验室测试和现场使用结果表明，优化后的控制器运行稳定可靠，满足加速器的需求。The MSC1210 control module is one of the most important power supply controllers of Heavy Ion Research Facility in Lanzhou ( HIRFL ), but there are several problems during beam tuning. In order to deal with the problems,the main chip’s program was redesigned. In this paper we introduced the controller’s fault phenomena, and analyzed the reasons; then scheduled the optimized program in detail. Several methods were employed to improve the system performance, including instruction receiving process which is based on state machine, the communication mode with parity mechanism, and the remote instruction reset method. Both laboratory and commissioning tests indicate that the optimized controller is stable and reliable, and meet the operation requirement of HIRFL.
中国散裂中子源( CSNS ) 的建造对中子探测器提出了非常高的要求，如更大的有效面积、二维位置灵敏、高计数率、高探测效率和低的 灵敏度等。与传统的模拟读出方法相比，数字法读出具有更高的计数率， 更小的数据传输量，更简单的电子学设计以及更高的信噪比。对数字法读出进行了理论计算，利用GEM探测器的原始数据分析了数字法读出的位置分辨率与读出条宽度的关系。结果表明，数字法读出对于位置分辨要求较低( 小于4 mm) 的大面积位置灵敏探测器是一种较好的选择，如CSNS 小角谱仪探测器。Efficient thermal neutron detectors with large area, two-dimensional position sensitive, high counting rate high detection efficiency and low gamma sensitivity are required to satisfy the demands for the China Spallation Neutron Source (CSNS). Compared with the traditional analog readout method, the digital readout method has the advantages of higher counting rate, smaller quantity of data transmission, simpler readout system and higher signal to noise ratio. The theoretical analysis of the digital readout method is reported in this paper. Used the raw data of GEM detector, the relationship between the position resolution and the width of the readout strip was studied. The results indicate that the digital readout method could be a good choice for the large area position sensitive detector where the requirement of position resolution is less than 4 mm, e.g. the detector of Small-Angle Neutron Scattering (SANS) diffractometer of CSNS.
冷中子三轴谱仪( CTAS ) 的屏蔽体对于保障工作人员安全、降低散射大厅本底及提高信噪比具有重要的意义。采用蒙特卡罗程序MCNP5 对谱仪各部分屏蔽体进行了计算，并结合Mcstas 程序确定了CTAS 入口处的中子源，大大提高了计算效率。经过模拟计算和优化表明：单色器后端使用厚350mm、密度4.6 g/cm3 的重混凝土，衔接屏蔽体使用厚300 mm、密度3.6 g/cm3的重混凝土，生物屏蔽采用厚150 mm、密度3.6 g/cm3 的重混凝土可保证屏蔽体外表面的剂量率满足散射大厅的剂量要求。The shielding of Cold neutron Triple-Axis Spectrometer( CTAS ) is important for radiation safety of workers, and reduce the background of scattering hall as well as enhancing the ratio of signal-to-noise. In this study,Monte-Carlo simulation was performed to conduct the calculation on the shielding of CTAS. To increase the calculation efficiency, neutron source was obtained by using Mcstas code. The results indicate that, in the case of heavy concrete ( density 4.6 g/cm3 ) with thickness of 350 mm for the shielding behind the monochromater, and heavy concrete ( density 3.6 g/cm3 ) with thickness of 300 mm for the other monochromater shielding, as well as the heavy concrete ( density 3.6 g/cm3 ) with thickness of 150 mm for biological shielding, the dose rate outside shielding may meet the requirement of national standard of China.
应用FLUKA 软件包对NE213 液体闪烁体中子探测器的探测效率进行了蒙特卡罗模拟，通过Birks 公式将中子产生的次级粒子的能量沉积转化为相应的光输出。根据不同探测阈值对模拟得到的光输出进行积分处理，计算出给定能量下探测器的中子探测效率。将模拟得到的闪烁体光输出、中心探测效率和平均探测效率随中子入射到探测器前表面位置的变化与实验数据进行比较，结果显示，FLUKA 模拟结果与实验值符合得很好，这为中子探测器的设计提供了可靠保证。A NE213 liquid scintillation neutron detector was simulated by using the FLUKA code. The light output of the detector was obtained by transforming the secondary particles energy deposition using Birks formula. According to the measurement threshold, detection efficiencies can be calculated by integrating the light output. The light output, central efficiency and the average efficiency as a function of the front surface radius of the detector, were simulated and
the results agreed well with experimental results.
采用蒙特卡罗方法模拟计算光子的探测效率需对高纯锗( HPGe ) 探测器进行准确的建模。模拟计算研究了HPGe 晶体长度对探测效率的影响，并在空间不同的测量位置对放射源进行测量，将模拟计算与实验测量相结合，对探测器晶体的尺寸进行调整，获得了HPGe 探测器晶体的模拟计算的准确尺寸，并在122s1 332 keV 能量范围内对模拟结果进行了验证。结果表明，在此能量范围内HPGe 探测器的探测效率的模拟计算值与实验测量值的相对偏差大多数在5% 内，并建立点源探测效率与探测器轴向距离的关系。The accurate shape of HPGe detector is needed in order to calculate its detection efficiency with Monte Carlo methods. In our calculation, the influence of the HPGe crystal size on efficiency has been investigated; the final crystal sizes were determined by comparison with experiments and were validated by the experimental efficiency obtained at several source-to-detector positions. The results show that when the crystal dimensions determined are used to calculate the detection efficiency in the energy range 122s1 332 keV, the relative deviations between simulated and most experimental results were within 5%. In addition, the relationship between detection efficiency and axial distance to detector was established.
测量了动能为2.0 MeV 的高电荷态离子152Eu20+入射Au 表面产生的Au 的Mζ，Mα 和Mβ 特征X射线和Eu 的M -X 射线。对X射线产生的微观机制进行了初步分析，并通过半经典两体碰撞近似，估算了Eu20+与Au 作用产生的Au 的M-X 射线和Eu 的M-X 射线的动能阈值。此结果对高电荷态离子与固体表面相互作用的动力学过程的研究以及在辐射能量转换效率研究中如何选取合适的弹靶组合具有重要的参考价值。It is measured that the characteristic X-ray spectra of Mζ，Mα and Mβ of Au and the characteristic X-ray spectra of M of Eu produced by the interaction of highly charged ions of 152Eu20+ with kinetic energy 2.0 MeV on Au surface. The micro-mechanism of X-ray excitation is preliminary analyzed. The kinetic energy threshold of M-X ray of Au and M-X ray of Eu emitted by Eu20+ with Au is estimated by semiclassical approximation theory of binary collision. The threshold has important referenced value in the study on dynamics of the interaction of highly charged ions with solid surface and on how to choose better target and projectile combination in the conversion efficiency of radiation energy.
室温下，将能量为250 keV He+ 离子注入z 切钽酸锂单晶，注量范围5.0x1014~5.0x1016 He+/cm2，应用三维轮廓仪、X射线衍射(XRD)、紫外可见(UV-Vis ) 光学吸收谱对未注入和注入样品进行了表征和分析。分析结果表明，在注量达到5.0x1016He+/cm2 时，样品表面出现大量凸起条纹，同时晶格沿着 方向出现明显肿胀，吸收边则表现出明显的注量相关性。注入样品在空气中放置60 d后，最高注量的样品表面原来凸起的条纹变为细长的裂纹，晶格应变及光学吸收边均出现较大的恢复。讨论了样品表面形貌、晶格应变和光学吸收边与He 行为的关系。The effects of 250 keV He + implantation in the fluence from 5.0x1014 to 5.0x1016 He+/cm2 on lithium tantalate at room temperature were investigated by 3D surface profiler, XRD and UV-Vis optical absorption spectroscopies.The experimental results show that a large number of raised stripes appear on the surface of the sample and the significant lattice swelling occurs along the direction [ 001 ] at the fluence of 5.0x1016 He+/cm2. The dependence of changes absorption edge on the fluences was revealed. After the samples had been exposed to the air for 60 days, the raised stripes on the surface have evolved into narrow cracks. Furthermore, the lattice strain and the optical absorption edge has also recovered dramatically. The relationship between surface morphology, lattice strain, optical absorption edge and behavior
of He-ions was discussed.
电子束辐照技术在剩余污泥处理应用中具有巨大潜能。大量研究表明，经高能电子束辐照，污泥中的各种病原菌会有不同程度的死亡、有机物( 包括非生物降解物质) 大量分解、脱水率提高，臭味减少，危害性降低和资源化应用潜能增加。综述了电子束辐照技术在剩余污泥处理中的优势，重点介绍该技术的应用现状、污泥中污染物的去除机理、处理效果和相关建设费用，并展望了该高新技术的应用前景和发展方向。Recently, electron beam irradiation has great potential in dealing with excess sludge . A great deal of studies showed that the electron beam irradiation played an enormous role in promoting the sludge harmless treatment. Most of pathogenicbacteria was dead and lots of organic substances, especially some non-biodegradable ones, were decomposed by the high electron beam irradiation. The irradiated sludge also had low water content, less odour, low hazard and a better application potential in utilization. This paper reviews the application of electron beam irradiation on excess sludge, the advantages and current situation of the irradiation technology. Mechanisms of removing contaminants, effects of treatment and the construction expense are mainly discussed. The future development of this advanced technology are
研究大蒜素重要活性成分二烯丙基二硫( Diallyl disulfide, 简称DADS) 对12C6+离子束辐照损伤小鼠的保护作用。利用4 Gy 剂量12C6+离子束对不同浓度DADS 预处理的雄性昆明小鼠进行单次全身照射。随后检测骨髓细胞微核率和肝组织中丙二醛(MDA) 含量、蛋白质总羰基含量、总抗氧化能力( TAOC)及谷丙转氨酶(ALT ) 活性。结果显示，与单纯照射组相比，低浓度DADS 预处理组骨髓细胞微核率和肝组织ALT 活性均显著降低(p<0.001)，而肝组织T-AOC明显增强( p < 0.05 )；中浓度DADS 预处理组肝组织中MDA 含量和蛋白质总羰基含量均显著减少( p < 0.05 )。结果提示，DADS通过抑制氧化应激，有效地保护了脂质、蛋白质和遗传物质免受12C6+离子束辐照引起的损伤。The radioprotective effect of Diallyl disulfide (DADS) on 12C6+ ion irradiation was studied. Pretreated with DADS of different concentration, male Kung-Ming mice were exposed to whole body irradiation with dosage of 4 Gy 12C6+ ion. The animals were sacrificed after irradiation. Then the bone marrow cells micronucleus rate, malondialdehyde (MDA) levels, content of protein carbonylation, total antioxidant capacity ( T-AOC) and alanine aminotransferase ( ALT ) activity were measured. As compared with those in irradiated group, the ratio of micronucleus cells in marrow and the hepatic ALT activity in the pretreatment group with low dose DADS decreased significantly ( p < 0.001 ). Similarly,the content of protein carbonylation and the levels of MDA droped dramatically in the group with middle dose DADS treatment ( p < 0.05 ). On the contrary, the hepatic T-AOC increased markedly in the group of pretreatment with low dose DADS ( p < 0.05 ). The results showed that DADS protect lipoid, protein and genetic material from 12C6+ ion irradiation by right of resisting oxidative stress.
研究了X 射线和重离子照射对人微血管内皮细胞的增殖、迁移、管样结构形成及基质金属蛋白酶表达的影响。Transwell 迁移实验结果显示，照射24 h 后，非毒性照射剂量照射能抑制HMEC-1 细胞的迁移，且重离子照射抑制内皮细胞迁移能力较X 射线的强。基质胶实验显示，重离子照射可显著抑制自发性管样结构的形成，但X 射线照射的抑制作用不明显。同时，明胶酶谱法证实了重离子照射可明显抑制HMEC-1 细胞中基质金属蛋白酶( MMP-2 和MMP-9 ) 的表达，而X 射线照射对此类酶几乎无任何影响，显示了重离子较X射线的肿瘤放疗优势所在。The study aims to explore the effect of 12C6+ ion and X-ray on proliferation, migration, tube formation and MMPS of human microvascular endothelial cells ( HMEC-1 ). Transwell migration experiment showed that the radiation could inhibit the migration of HMEC-1 in sub-lethal dose 24 h after irradiation. Furthermore, the inhibition ability of 12C6+ ion was stronger than that of X-ray. Matrigel experiment indicated that 12C6+ ion suppressed the tube formation of HMEC-1 spontaneously. However, the inhibitory effect of X-ray had no significance. Meanwhile, Gelatin Zymography showed the expression of MMP-2 was inhibited obviously by 12C6+ ion, while X-ray had little effect on the expression of MMP-2. In conclusion, 12C6+ ion is superior to X-ray in radiotherapy of tumor.
简要地介绍了美国激光惯性约束聚变能源( LIFE ) 的研究现状与发展前景。基于美国国家点火装置( NIF ) 的近期进展，美国利弗莫尔实验室提出了激光惯性约束聚变能源设想，并开始了分解研究。设想用新型二极管泵浦固体激光器产生1.4~2.0 MJ 的激光能量，靶丸聚变增益25~30，打靶频率10~15Hz，实现350~500 MW聚变功率，相当于聚变中子源强1.3×1020 ~1.8×1020 n/s。以此驱动次临界裂变包层，使能量再倍增4~10 倍，实现1 GW电功率的输出。采用创新设计的燃料元件，包层可达到90%以上的燃耗深度，形成一个安全、无碳、燃料资源丰富、核废料少、可持续发展的新型核能源系统。In this paper the present study situation and prospect of the American laser-based Inertial Confinement Fusion Energy ( LIFE ) are briefly introduced. It is based on recent progress of National Inertial Facility ( NIF ) and related research have begun. On the assumption of using laser energy of 1.4 to 2.0 MJ, the target fusion gain G=25~30, the repetition rate 10 to 15 Hz, the fusion power of 350 to 500 MW or neutron source power of 1.3×1020 to 1.8×1020 n/s could be achieved. For a sub-critical fission blanket driven by this fusion neutrons power, energy multiplication M of 4~10 and several GW of thermal power could be obtained. By novel design on fuel pins, burnup more than 90% would be achieved for heavy metals in the blanket. Inertial Confinement Fusion-fission energy is a promising concept, which characterized by inherent safety, richness in nuclear fuel resources, minimization of nuclear waste, non-CO2 emitting ,and it is a sustainable energy source.
针对未来先进核能装置候选结构材料在高温和应力等条件下抗辐照性能的评价与快速筛选的需求，基于兰州重离子研究装置( HIRFL ) 可提供的离子束流条件，设计制作了国内第一套高温应力材料载能离子辐照装置。该装置由束流扫描及探测系统、高温系统、应力系统、真空冷却系统和远程控制系统等5 部分组成，可以同时提供高温和拉/ 压应力下材料的离子束均匀辐照件，温区覆盖了室温至1 200 °C范围，拉/ 压应力范围为0 ~1176 N，x-y 方向均匀扫描面积可大于40 mmx40 mm。利用该装置，已经成功进行了多次高温和应力条件下载能离子辐照先进核能装置候选材料的实验研究，并取得了初步成果。In order to expedite the evaluation of properties of irradiated materials and the selection of candidate materials for future nuclear energy systems, we developed a specific ion irradiation equipment installed on the Heavy Ion Research Facility of Lanzhou ( HIRFL ) for materials under high temperature and stress. This equipment consists of ion beam scanning and detector system, high temperature load system, stress load system, water cooling system as well as telecommunication and control system. It can supply a wide range of temperature (from room temperature to 1 200 °C ) and stress ( pull / push from 0 to 1 176 N) simultaneously for materials under ion irradiation. The x-y scanning area with high uniformity is larger than 40 mm40 mm. This is the first suit of ion irradiation equipment made in China that can be used to study co-operating effects of high temperature and stress in an irradiated material. It has been successfully used several times for materials irradiations under high temperatures and stress, which proved that the new equipment has very good performances in experiments.