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2010年  第27卷  第2期

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核物理
能量密度泛函理论和有限力程可分离对相互作用研究核的超流性质
马中玉, 田源, P. Ring
2010, 27(2): 121-129. doi: 10.11804/NuclPhysRev.27.02.121
摘要:
在相对论密度泛函理论框架下引入了可分离的对相互作用, 它的参数是由拟合核物质中Gogny力对关联性质来确定。在有限核的相对论HartreeBogoliubov和相对论准粒子无规位相近似的理论框架下, 建立了可分离对相互作用在球形核和变形核中粒子粒子道矩阵的计算方法。通过Talmi和Moshinsky变换, 这种新的对相互作用在坐标空间下可以展开成一系列可分离项, 并且很快收敛。它不仅保持了平移不变性, 而且作为有限力程的对力, 可以避免零程对力在高动量截断的困难。通过对Sn同位素链核基态、 E2和E3激发态性质, 以及Sm同位素链基态的性质研究, 发现可分离对相互作用能够再现用Gogny对力得到的球形核的超流性质, 并能够很好地符合已有的实验结果。这种方法还可用来描述任意微观对相互作用, 并推广于三轴形变原子核以及转动系统的研究。为考虑角动量投影和粒子数投影的生成坐标(GCM)方法和粒子振动耦合(PVC)理论提供更加真实的对关联性质描述。A separable pairing interaction is introduced in the covariant density functional theory. The parameters of the separable force are adjusted to reproduce the pairing properties of the Gogny force in nuclear matter. It preserves translational invariance and has finite range. Applying well known techniques of Talmi and Moshinsky, this pairing interaction can be used in relativistic and in non-relativistic Hartree-Bogoliubov or Hartree-Fock-Bogoliubov calculation of finite nuclei. It avoids the complicated problem of a cutoff at large momenta or energies inherent in other zero range pairing forces. This finite range separable pairing force is applied to study the properties of the ground and excited states for spherical Snisotopes in the relativistic Hartree Bogoliubov and relativistic quasiparticle random phase approximation. The superfluid properties of the ground state for the axially deformed Smisotopes are also studied in the deformed RHB theory with the separable pairing force. It has been shown that with this force the pairing properties of ground states can be well depicted on almost the same footing as with the original Gogny pairing interaction. There are also many extensions of relativistic density functional theory beyond mean field, such as applications using projection onto subspaces with good symmetries, generator coordinate methods, or investigation of complex configurations in the framework of particle vibrational coupling(PVC). All these methods require a more realistic description of pairing correlations in the future.
Skyrme能量密度泛函在深度垒下熔合反应中的初步应用
王小平, 田俊龙, #, 李贤, 晏世伟
2010, 27(2): 130-135. doi: 10.11804/NuclPhysRev.27.02.130
摘要:
基于Skyrme能量密度泛函并对动能密度按扩展的ThomasFermi半经典近似展开到四阶项, 探索了深度垒下熔合反应的熔合截面急剧下降现象。 通过分析熔合反应的入射道势和熔合截面来选择Skyrme参数, 进而探索了深度垒下熔合反应与核物质状态方程之间的关系。The Skyrme energydensity functional together with the extended semiclassical ThomasFermi method is applied to the study of heavy ion fusion reactions at deep subbarrier energy. The relation between heavy ion fusion reactions at deep subbarrier energy and the equation of state (EOS) of nuclear matter is further probed by selecting different sets of Skyrme force parameters to reproduce the experimental excitation functions.
Bi同位素链上原子核α衰变性质的理论研究
王永佳, 张鸿飞, #, 王艳召, 董建敏, 蔡凌志, 李君清, 左维
2010, 27(2): 136-139. doi: 10.11804/NuclPhysRev.27.02.136
摘要:
采用结团模型(cluster model)计算了从 10752Te到292116共443个核素α衰变的半衰期, 所得结果与实验值符合得很好, 显示了结团模型可以成功地应用于研究原子核α衰变的性质。 同时研究了Bi同位素链上奇A核α衰变的半衰期, 计算结果与已有的实验值的偏差一般在3倍以内, 进而对实验上未知α衰变半衰期的原子核的性质进行了预言。 这有助于将来在实验室探测与鉴别这些原子核以及研究它们的α衰变性质。 理论与实验的比较将加深人们对原子核结构的认识。 The αdecay halflives of 443 nuclei are investigated within the cluster model(CM). The results are compared with the experimental data. The coincidence between theoretical results and the experimental data are satisfied, implying the CM works quite well for the study on ??decay properties. Then the adecay halflives of Bi isotopes are calculated. The results are consistent with the known experimental data. The αdecay halflives of the Bi isotopes without experimental data are predicted, which is useful for the future experimental detection and identification of these nuclei.
双奇核170Re高自旋转动带分析(英文)
王华磊, 宋立涛, 赵维娟, 刘忠侠, 张玉虎, 周小红, 郭应祥, 雷祥国, 柳敏良, 郑勇, 温淑贤, 竺礼华, 吴晓光, 许甫荣
2010, 27(2): 140-145. doi: 10.11804/NuclPhysRev.27.02.140
摘要:
通过重离子熔合蒸发反应142Nd(32S, 1p3nγ)170Re布居了缺中子双奇核170Re的高自旋激发态, 识别出了该核的一条转动带并建议了其组态为πh1/2νi13/2。 基于对同中子素能级系统性、 旋称反转系统性、 带内B(M1)/B(E2)、 准粒子Routhians、 动力学转动惯量和Total Routhian Surface(TRS)等带结构特征的详细分析和讨论。One highspin rotational band in neutron deficient oddodd nucleus 170Re has been identified and assigned to the πh1/2νi13/2 configuration through the 142Nd(32S,1p3nγ)170Re reaction. The band is analyzed on the basis of the arguments of energy systematics, signature inversion systematics, intraband B(M1)/B(E2) ratios, quasiparticle Routhians, dynamic moment of inertia and Total Routhian Surface(TRS) calculations. From detailed analyses on its structural properties, the configuration, spins and parity have been further assigned for this rotational band.
Se同位素的形状共存
刘颖, 许甫荣, #, 曹钟斌
2010, 27(2): 146-149. doi: 10.11804/NuclPhysRev.27.02.146
摘要:
基于形变WoodsSaxon势下的推转壳模型对Se同位素进行TotalRouthian Surface (TRS) 计算。 结果表明, 原子核的形状随中子数变化很明显。 对66,72, 92, 94Se 基态TRS图进行分析, 发现缺中子同位素和中子滴线附近核素均存在扁椭球和长椭球的形状共存。 分别对72Se和94Se进行推转计算,长椭球和扁椭球形状在低推转频率下共存, 由于g9/2闯入轨道的影响, 随着推转频率的增加,扁椭球形变逐渐消失,长椭球形变带成为转晕带。
Nuclear shape change and shape coexistence in the Selenium isotopes have been investigated by TotalRouthianSurface(TRS) calculations. It is found that nuclear shapes vary significantly with increasing neutron number. The TRS calculations for the ground states of 66, 72, 92, 94Se isotopes show that both neutrondeficient and neutrondripline Selenium isotopes have oblate and prolate shape coexistence. The cranking shellmodel calculations for 72, 94Se give that prolate and oblate shape coexistence in low rotational frequency. However, oblate rotational bands disappear and prolate rotational bands become yrast bands with increasing rotational frequency, which is due to the intrusion of the g9/2 orbitals.
Pb附近奇A核同质异能态半衰期的简单规律
钱以斌, 任中洲, 倪冬冬
2010, 27(2): 150-154. doi: 10.11804/NuclPhysRev.27.02.150
摘要:
对Pb附近Z=78—82奇A核同质异能态IT衰变(或称为同质异能跃迁包括γ跃迁和内转换)的实验数据进行了系统的分析, 发现了奇A核同质异能态IT衰变半衰期的一个简单的规律:同位素链上角动量和宇称相同的同质异能态, 半衰期的对数随质量数之间符合二次曲线关系。 这说明了IT衰变的半衰期和质量数A之间有着一个指数关系。 对这一段同质异能态衰变中跃迁多极性的分析可让人们对有关物理性质有更清楚的认识。 对发现的简单规律也给出了可能的物理解释。
三维谐振子Wigner函数的星乘解
陈德胜, 王亚辉#, 王垚, 马凯
2010, 27(2): 155-159. doi: 10.11804/NuclPhysRev.27.02.155
摘要:
Wigner函数作为相空间中的一个准概率分布函数, 也是密度矩阵的特殊表示形式, 具有十分重要的物理意义。 首先介绍了Wigner函数的性质及其计算方法, 然后利用星本征方程(Moyal 方程)计算了三维谐振子的Wigner函数。 最后讨论了在相空间中描述声子与电子(或光子)相互作用的方法, 并得到了跃迁几率在相空间中所满足的方程。 As a quasiprobability distribution function in phasespace and a special representation of the density matrix, Wigner function has great significance in physics. In this paper, first, Wigner function’s characteristic and calculation approach are introduced. Then, with Stareigen equation we obtain the Wigner function for threedimensional harmonic oscillator. In the end, we discuss the method describing the interaction between phonons and electrons (or photons) and obtain the equation that transition probability satisfies in phase space.
QCD手征相变中的π介子增强(英文)
徐晓梅, 傅永平, 李云德, #
2010, 27(2): 160-163. doi: 10.11804/NuclPhysRev.27.02.160
摘要:
讨论了在LHC的Pb-Pb碰撞过程中,如果QGP SU(2)手征相变出现二级相变,那么系统将会有π弦产生,并且π弦最终将衰变为π介子。于是以上效应将导致在低动量区域(p~150—400 MeV)内的π介子增强。对应于不同的冷却温度Tf=130,120,110 MeV,产生于π弦衰变的π介子的数量分别是Nt≈270,150, 60. It is pointed out that if the QGP SU(2) chiral phase transition in the LHC PbPb collision process is taken place and the phase transition is in the second order, then pion strings will be formed, and decay. These phenomena lead to the pion enhancement in the low momentum region(p150—400 MeV) and the number of pions produced from pion string decay can be estimated about Nt≈270, 150, 60 for different freeze temperature Tf=130, 120, 110 MeV respectively.
加速器
利用HIRFL-CSR开展分子离子复合离解研究的可行性分析
蔡晓红, 于得洋, 杨建成, 冒立军, 阮芳芳, 卢荣春, 邵曹杰, 宋明涛, 薛迎利, 王伟
2010, 27(2): 164-169. doi: 10.11804/NuclPhysRev.27.02.164
摘要:
介绍了储存环高精度分子谱学研究的科学意义、 国内外研究现状和利用HIRFL-CSR开展该项研究的优势, 着重论证了HIRFL-CSR分子离子注入实验环的总体设计方案和技术方案。 通过在HIRFL-CSR实验环上增建一条分子离子注入线, 将实验环改造成能兼顾现有物理实验和大分子物理研究的综合性研究平台, 为分子离子复合离解研究提供良好的技术支撑。 特别是质量数大于70的分子离子, 能显著提高其能量分辨。 In the present paper, it is introduced the scientific background and the current status of the high precision spectroscopy of the molecular ions at cooler storage ring. The advantages to study the dissociative recombination(DR) processes using cooler storage ring CSRe are discussed. The physics design,the main parameters of the injection beam line and the injection of the molecular ions into the CSRe and the key techniques are described in detail. With a new injection beam line,HIRFL-CSRe will be reconstructed to a multidiscipline research platform,offering good opportunities for the study of DR processes of molecular ions,especially for that of the molecular ions of m>70 amu with much improved resolution.
基于P2P技术的CSRe冷却装置控制系统设计
何旭春, 乔卫民, 敬岚, 郭玉辉, #, 龙银东
2010, 27(2): 170-173. doi: 10.11804/NuclPhysRev.27.02.170
摘要:
HIRFL-CSR工程对CSRe冷却装置电子冷却部分的控制系统在实时性和可靠性方面提出了非常高的要求。 电子冷却工作环境复杂, 各种干扰难以预测。 从电子冷却的控制系统改进出发, 以实现电子冷却的自动调束为目标, 以高端FPGA和ARM嵌入式系统为基础, 采用P2P通讯技术和神经元网络算法来实现对电子冷却的自动控制。 该控制系统对电子冷却控制的完善提供了先进的硬件平台和软件实现方案。
In the HIRFL-CSR project,it needs the high performance requirement in real time and reliability for the control system of CSRe’s cooling equipment——Cooler. Simultaneously, the running environment of the Cooler is very complex and it is difficult to predict various kinds of interference. To solve these problems, we focus on the improvement on the control system of the Cooler. The high performance FPGA and ARM embedded systems are used to realize the beam commissioning automatically,and the P2P(Peer to peer) technology and the neural network algorithm are adopted to implement the automatic control of the Cooler. The system provides the advanced hardware platform and the design proposal for the cooling control system.
核技术
64通道一维位置灵敏电流分布探测器及其数据获取系统
王 伟, 于得洋, 佘乾顺, 徐治国, 陈婧, 苏弘, 蔡晓红, #
2010, 27(2): 174-177. doi: 10.11804/NuclPhysRev.27.02.174
摘要:
针对高流强粒子束与绝缘毛细管相互作用的特点, 设计制作了一套64通道一维位置灵敏电流分布探测器及其配套的数据获取系统, 该探测器可分辨最小直径为1 mm的束斑, 通过数据获取系统可实现可视化自动数据采集。 用2 nA和200—2000 eV电子对探测器进行了定标, 并用10 μA和2000 eV的电子束穿越锥形毛细管后的出射电子, 对探测器及数据获取系统进行测试, 获得了出射粒子的位置分布谱及能量信息。 A 64channel position sensitive current distribution detector with 1 mm position resolution was developed, while the data acquisition system is based on the LabVIEW software. The test result obtained by using a 2 nA, 200—2000 eV electron beam deflecting by different voltages and the position spectra of 10 μA, 2000 eV electrons transmitted through a glass capillary was measured. The result indicated that the detector can be used to detect the charged particles with strong beam current through the capillary.
γ探测器中子灵敏度标定技术
李如荣, 郭洪生, 胡清元, 李忠宝, 张建华
2010, 27(2): 178-181. doi: 10.11804/NuclPhysRev.27.02.178
摘要:
叙述了γ探测器的14.1 MeV中子灵敏度标定原理和屏蔽方法,利用MCNP程序建模, 优化设计了对γ和中子高屏蔽性能的屏蔽体。 实验研究表明, 其信噪比最高达10∶1, 比测量点本身的信噪比1.35∶1提高了7倍, 从而实现了γ探测器的中子灵敏度标定。 It is introduced that a method and principle for calibrating 14.1 MeV neutron sensitivity of γray detector. A shield system for scattering neutrons and γrays has been optimized by MCNP code. The experimental results show that the signaltonoise ratio of the system is about 10:1, 7 times higher than the value of 1.35〖KG-*4〗∶〖KG-*4〗1 without shield system. Calibration of neutron sensitivity of γray detector is then accomplished.
γ辐射多层组合屏蔽的蒙特卡罗方法模拟及其论证
林卿, 杨永栩, 何云, #, 马玉刚, 曾思良
2010, 27(2): 182-186. doi: 10.11804/NuclPhysRev.27.02.182
摘要:
应用蒙特卡罗(MC)方法通用软件(MCNP4B程序)建立多层组合模型, 模拟计算了γ辐射非均匀屏蔽的问题, 比较研究各种组合方法以确定最佳的方案。 同时对模拟结果与理论计算、 实验测量三者进行综合分析, 说明了三者结论的一致性, 也说明了用MC方法来模拟非均匀屏蔽的可行性和多层组合屏蔽设计的实际意义。 In this paper, the multilayer model was established to calculate γradiation nonuniform shielding problem, and various combinations of methods were investigated to determine the optimal option. At the same time, the comprehensive analysis of the simulation results, the theoretical calculation and the experimental measurements show that the consistency among them. Practical significance is also shown that the application of Monte Carlo method to simulate the nonuniform shielding feasibility and multilayer shielding design.
单次分子镀法制备部分La系及238U靶的实验研究
白静, 吴晓蕾, 林茂盛, 范芳丽, 丁华杰, 雷富安, 李小飞, 秦芝, 郭俊盛
2010, 27(2): 187-191. doi: 10.11804/NuclPhysRev.27.02.187
摘要:
采用单次分子镀方法研究了异丙醇硝酸体系中电流密度、 分子镀持续时间及两极间距离对镀层性能和电沉积效率的影响, 确定了制备La, Sm, Eu, Gd, Tb靶及238U靶的最佳工艺条件。 因制备的靶不同, 电流密度一般介于2—8 mA/cm2之间, 两极间最优距离为3 cm, 分子镀1 h, 用分光光度法测定各靶的沉积效率均高于85%。 利用扫描电子显微镜(SEM)对部分靶的表面形貌分析后发现靶面结构均匀致密。 目前制得的Gd靶和Tb靶已用于中国科学院近代物理研究所加速器SFC低能核化学终端上, 利用19F束流轰击, 分别产生了Ta和W 的短寿命同位素, 从而成功完成了 Db(Z=105)及Sg(Z=106)的模型试验。Preparation of La, Sm, Eu, Gd, Tb and 238U targets from the mixture of isopropanol and nitric acid solution are studied by using singlecycle molecular plating technique. To determine the optimum conditions for the deposition process, the effect of current density, deposition time and distance between the two electrodes on the quality and electrodeposition yield of the target films are investigated individually. Depending on the deposited metal, the current densities are found to be 2—8 mA/cm2 and the suitable distance between the two electrodes is 3 cm. With the spectrophotometry method, the electrodeposition yields for all the targets prepared are found to be higher than 85% after one hour’s deposition. The composition and morphological structure of some targets are characterized by scanning electron microscope(SEM) and it can be seen that the surface of the targets are uniform and intact. Shortlived isotopes of Ta and W were produced from natural Gd and Tb targets bombarded by 19F beam at the SFC low energy radiochemical terminal of Institute of Modern Physics, Chinese Academy of Sciences, respectively, and successfully applied in the model experiment of Db(Z=105) and Sg(Z=106).
交叉学科
两种保护剂对C离子诱导小鼠急性肝损伤的应答
张录卫, 张红, #, 刘阳, 郝冀方, 赵卫平
2010, 27(2): 192-196. doi: 10.11804/NuclPhysRev.27.02.192
摘要:
比较了N乙酰半胱氨酸(NAC)及乙酰左旋肉毒碱(ALCAR)对12C6+离子照射小鼠的损伤效应, 并探讨了其可能的作用机制。 利用4 Gy剂量的12C6+离子束对预先给予NAC(100 mg/kg)和ALCAR(100 mg/kg)保护的昆明小鼠进行单次全身照射。 随后检测肝组织中总抗氧化能力(TAC)、 DNA单链断裂和细胞凋亡率。 结果显示, 与照射对照组相比, 提前给予NAC和ALCAR均极显著地增强了肝组织的抗氧化能力(P<0.001), 减轻了12C6+离子导致的肝组织中DNA断裂(P<0.001)和细胞凋亡(P<0.001)。 此外, 还发现ALCAR组抗重离子辐照损伤的能力显著地高于NAC组(P<0.05)。 实验结果提示了NAC和ALCAR可通过抵御组织内的氧化胁迫, 阻止DNA链的断裂和细胞的凋亡, 实现对C离子辐照损伤的保护效应。 而且ALCAR比NAC可能更适合成为有潜力、 有希望的抗C重离子辐射药物。 The present study was to evaluate the effect and mechanism of Nacetylcysteine(NAC) and AcetylLCarnitine hydrochloride(ALCAR) against 12C6+ ion beams on acute injury in the mouse liver. Pretreated with NAC (100 mg/kg) and ALCAR(100 mg/kg), KunMing mice were exposed to wholebody irradiation with the dose of 4 Gy. Mice were killed 2 h after irradiation, and then the liver tissues were quickly removed. TAC was measured by using chemical reagent kids, and DNAsingle strand breaks were determined by single cell gel electrophoresis, and the percentage of cell apoptosis were assayed by flow cytometry method. The results showed that NAC and ALCAR pretreatment significantly enhanced TAC(P<0.001), alleviated DNAsingle strand breaks(P<0.001) and cell apoptosis(P<0.001) of the liver tissues. Moreover, ALCARmediated radioprotection induced by 12C6+ ions is stronger than that of NAC (P<0.05). The data suggests that NAC and ALCAR both can ameliorate acute injury caused by 12C6+ ions in mice. In this study, NAC and ALCAR exert their radioprotective effect by virtue of resisting oxidative stress, enhancing TAC, alleviating DNAsingle strand breaks as well as cell apoptosis. Furthermore, the data imply that NAC and ALCAR may be suitable and promising as radioprotective drug against carbon heavy ions.
低能N+注入E.coli 诱发的HRS/IRR与抗氧化物酶关系的初探
杨天佑, 王铁固, 田静, 常景玲, 秦广雍
2010, 27(2): 197-201. doi: 10.11804/NuclPhysRev.27.02.197
摘要:
研究了30 keV N+注入E.coli 诱发的辐射超敏感效应/增强的辐射性(HRS/IRR)及该效应诱发时E.coli细胞内抗氧化物酶(SOD和CAT)的诱导表达, 探讨了细胞内抗氧化物酶的诱导与HRS/IRR诱发之间的关联。 研究结果显示, HRS诱发剂量范围内(0—5×1014 N+/cm2), E.coli细胞内超氧化物岐化酶(SOD)的酶活基本维持在10 Us/mg的较低水平, 过氧化氢敏(CAT)酶活也都低于8 Us/mg; IRR诱发的剂量范围内(5×1014—10×1014 N+/cm2 ), SOD和CAT活性升高并分别达到了58 Us/mg和26 Uc/mg的最高水平。 研究结果初步表明, 低能离子注入E.coli HRS/IRR的诱发与细胞内抗氧化物酶的诱导关系密切。 The inducement of hyperradiosensitivity/increased radioresistance(HRS/IRR) and activities of antioxidases in Escherichia coli implanted by 30 keV N+ and relationship between them were investigated. The results showed the change trend of the survival rate and the activity of superoxide dismutase(SOD) and Catalas(CAT) of E. coli K12 was consistent. The activity of SOD and CAT of E.coli were lower, less than 10 and 8 U/mg, when the HRS was induced at 0—5×1014  N+/cm2 doses. And the activity of SOD and CAT of E.coli increased and reached highest rate, were 58 and 26 U/mg respectively, when the IRR was induced at 5×1014—10×1014 N+/cm2 doses. It could be concluded that the change of SOD and CAT activity was related with the HRS/IRR.
Survivin表达在高LET射线诱导细胞凋亡中
金晓东, 李强, 吴庆丰, 李萍, 陶家军, 巩莉, 戴中颍, 刘新国
2010, 27(2): 202-205. doi: 10.11804/NuclPhysRev.27.02.202
摘要:
先前的研究表明, 肿瘤细胞中survivin的高表达与细胞对高传能线密度(LET)射线的辐射抗性相关。 研究了survivin表达在高LET射线诱导的细胞凋亡中的作用, 发现抑制survivin表达对高LET C离子辐射诱导的Bcl-2和Bax表达没有明显的影响。 在高LET射线辐照中, survivin可能通过抑制caspase-3和-9活性的途径, 抑制了细胞凋亡。It has been proven that overexpression of survivin in cancerous cell lines is related to the radioresistance of cells to highLET radiation in previous work. In this study, action mechanisms of survivin gene in apoptosis induced by highLET radiation were investigated. We found that inhibiting survivin by siRNA had no notable influence on Bcl-2 and Bax expressions induced by carbon ions. Survivin depressed cell apoptosis through the inhibition of the activities of caspase-3 and -9 possibly in cell apoptosis induced by highLET radiation.
空间辐射生物学研究进展
李文建, 党秉荣, 王转子, 魏巍, 荆西刚, 王弼乾, 张斌团
2010, 27(2): 206-211. doi: 10.11804/NuclPhysRev.27.02.206
摘要:
空间电离辐射尤其是高能带电粒子辐射可造成生物机体的严重损伤, 是载人航天飞行的关键性限制因素之一。 研究表明, 带电粒子的生物学效应与其性质、 剂量以及不同生物学终点有关; 此外, 微重力环境可能会影响空间辐射生物学效应。 从多年来的空间搭载实验研究和地基模拟实验研究两个方面, 综述了空间辐射的生物损伤效应及其与微重力环境复合作用的生物效应。Space radiation, particularly induced by the highenergy charged particles, may cause serious injury on living organisms. So it is one critical restriction factor in Manned Spaceflight. Studies have shown that the biological effects of charged particles were associated with their quality, the dose and the different biological end points. In addition, the microgravity conditions may affect the biological effects of space radiation. In this paper we give a review on the biological damage effects of space radiation and the combined biological effects of the space radiation coupled with the microgravity from the results of space flight and ground simulation experiments.
基于共轭梯度法的调强放疗射束强度分布优化
曹瑞芬, 裴曦, 郑华庆, 景佳, 程梦云, 李贵, 吴宜灿, FDS Team
2010, 27(2): 212-217. doi: 10.11804/NuclPhysRev.27.02.212
摘要:
针对逆向调强放疗中强度分布优化涉及的参数多, 且临床上对其优化速度要求高的特点, 将医生期望的靶区剂量和周围正常组织剂量限制转化为二次函数形式的目标函数, 然后利用共轭梯度法对该目标函数进行优化。 最后采用一例C形靶区紧密包围危及器官的模拟病例和一例临床常用的前列腺实例, 在PC机(CPU E7200@2.53GHz, 2.00GB内存, Windows XP)上对强度分布优化效果进行测试, 对模拟病例10 s便找到最优解; 而对前列腺病例20 s便可以找到最优解; 且两个测试病例优化所得强度分布对应的剂量分布均满足要求。 测试结果表明, 采用共轭梯度法优化强度分布具有快速和效果好的优点, 因此可以将其应用在精确放疗系统中。
The beam intensity map optimization of Intensity Modulated Radiation Treatment(IMRT) is a large scale optimization problem because of thousands of parameters involved. A fast and efficient approach was studied in the paper according to the clinical requirement for high speed and good results. Firstly, the clinical prescribed dose of Planning Target Volume(PTV) and dosevolume constraints of Normal Tissue and Organ at Risk(OAR) were transformed into a quadratic objective function. And then Conjugate Gradient(CG) was adopted to optimize the objective function. At last, a simulated case and a clinical case were used to test the approach. The results showed that the optimization process need 40 s while satisfied results could be obtained in 10 s for simulated case and the optimization process need 1 min and 20 s while optimized results could be obtained in 20 s for the clinical prostate case. So it can be found that the approach of proposed in this paper is valid and efficient, and can be used to the accurate radiation therapy system.
弧形调强放射治疗对剂量计算方法的要求
李敏, 勾成俊, 吴章文, 侯氢#
2010, 27(2): 218-222. doi: 10.11804/NuclPhysRev.27.02.218
摘要:
在弧形调强放射治疗的治疗计划设计中, 由于包含有很多照射方向, 调强最优化的射束元矩阵计算需要很大的计算量和存储量, 为提高计算效率常使用简化剂量计算模型计算射束元矩阵, 因此有必要研究简化模型对治疗计划质量产生影响。 对一个模拟例子和一个临床实例, 使用没考虑散射效应的原射线剂量计算模型计算射束元矩阵, 由此进行最优化计算。 在得到最优化强度分布后, 通过比较原射线剂量计算模型和微分卷积剂量计算模型得到的剂量分布, 研究了不同射束数目条件下, 使用简化剂量计算模型计算射束元剂量矩阵对最终的剂量分布质量的影响。 结果表明, 在射线束很多的情况下(对应弧形调强照射), 用简化的剂量计算模型, 即不考虑散射来计算射束元剂量矩阵, 会导致靶区剂量分布的质量大大低于预期的剂量分布质量, 因此, 弧形调强放射治疗的最优化计算中, 有效考虑散射的影响是必要的。 In the treatment planning for arcintensitymodulated radiation therapy, because many irradiation directions are involved, the computing time and storage space needed for calculating beamlet dose matrices in optimization is quite heavy. In order to improve the computation efficiency, the simplified dose calculation is often used for the calculation of the dose matrices. Thus, it is deserved to study how this simplification could influence the quality of the treatment plan. In this paper, a simulation and a clinical case are adopted. Using the primary dose calculation model without taking into account the scattering effect to generate the dose matrices of beamlets, the optimization for beam intensity profile are firstly carried out. Then, based on the obtained intensity profile, the dose distributions are recalculated by using the primary dose calculation model and the differential convolution superposition dose calculation model which is more accurate but more time consuming. By comparing dose distributions obtained by this two models, the influence of using simplified model for dose matrix calculation on beam profile optimization is studied. The results demonstrate that when the beam number is large(corresponding to the arcmodulated radiation), using the simplified model for the calculation of dose matrix of beamlets will reduce the quality of dose distribution greatly comparing with the expected dose distribution quality. Thus it is very necessary to correctly take into account the scattering effect in beam profile optimization for the arcintensitymodulated radiation therapy.
低速高电荷态重离子在C60薄膜中引起的势效应研究
付云翀, 姚存峰, 金运范
2010, 27(2): 223-227. doi: 10.11804/NuclPhysRev.27.02.223
摘要:
为了研究低速高电荷态离子在C60薄膜中引起的势效应, 用能量为200 keV的高电荷态Xen+(n=3, 10, 13, 15, 17, 20, 22, 23)离子辐照了C60薄膜。用原子力显微镜(AFM)和Raman散射技术分析了辐照过程中高电荷态Xen+离子所储存势能在C60薄膜中引起的效应, 即势效应。AFM分析结果表明, 辐照C60薄膜的表面粗糙度随辐照Xen+离子电荷态(即势能)的增加而减小, 揭示了势效应的存在。而Raman分析结果表明, 由于Xe离子的动能远大于其所储存的势能, 因此, 尽管有表面势效应的影响, 但在Raman分析的深度范围内, 弹性碰撞还是主导了C60薄膜的损伤过程。In order to investigate the potential effect in the C60 films induced by slow highlycharged ion(SHCI), the irradiation experiments of C60 films were performed by using Xen+ ions(n=3, 10, 13, 15, 17, 20, 22, 23). The irradiated C60 films were analyzed by means of AFM and Raman scattering. The analysis results indicated that the surface roughness of C60 films irradiated is decreasing with the increase of the charge state of Xen+ ions(potential energy stored in Xen+ ions).This reveals the existing of the potential effect. The results of the Raman spectra showed that in despite of existing influence of potential effect, the damage process of C60 films in the area for analysis depth of Raman is dominated by the elastic collisions, because the deposited potential energy of Xen+ ion in C60 films is much less than its kinetic energy.