介质中的核子-孩子碰撞截面及其对原子核反应总截面的影响

给出了一个在较大能量范围内描述介质中核子－核子碰撞截面的计算公式，并结合微观修正的Ｇｌａｕｂｅｒ模型，研究了介质效应对原子核反应总截面的影响。     

介质中的核子–孩子碰撞截面及其对原子核反应总截面的影响

给出了一个在较大能量范围内描述介质中核子-核子碰撞截面的计算公式,并结合微观修正的Glauber模型,研究了介质效应对原子核反应总截面的影响.     

核子-核子碰撞截面对同位素标度参数α的介质效应

核子能量在40—60MeV能区范围,对在两对重离子中心碰撞系统⁴⁰Ca+⁴⁸Ca和⁶⁰Ca+⁴⁸Ca以及¹¹²Sn+¹¹²Sn和¹²⁴Sn+¹²⁴Sn 的反应中就同位素标度参数α对于核子-核子碰撞截面σ^med_NN(α_m)的介质 关键词： 同位素标度行为 介质效应 核子-核子碰撞截面 重离子碰撞     

核子-核子碰撞截面对同位素标度参数α的介质效应

核子能量在40-60 MeV能区范围,对在两对重离子中心碰撞系统40Ca 48Ca和60Ca 48Ca以及112Sn 112Sn和124Sn 124Sn的反应中就同位素标度参数a对于核子.核子碰撞截面σmedNN(αm)的介质效应进行了研究.结果发现,核子一核子碰撞介质效应对同位素标度参数n具有明显的影响.就产生这种介质效应的机理进行了分析和讨论.     

从能谱中提取核子-核子碰撞截面的信息

用同位旋相关的量子分子动力学(IQMD)模型计算了入射能量在30~200 MeV/u内, 不同中质比的反应系统(76Zn+76Zn, 76Ge+76Ge,76Se+76Se和76Kr+76Kr)碰撞产生的原子核阻止和反应产物能谱。 发现原子核阻止和不同方向的动能比值有很强的关联性,且可以用垂直方向和平行方向的碎片总动能比值的平方根近似地代替原子核阻止,用来提取同位旋相关介质中的核子-核子碰撞截面的信息。在核反应实验中,很容易测量到该物理量, 它是一个较好的探针。 The collision of different neutron/proton ratio, intermediate mass reaction systems(76Zn+76Zn, 76Ge+76Ge,76Se+76Se and 76Kr+76Kr) at the beam energy of 30~200 MeV/u are studied by using isospin dependent quantum molecular dynamics(IQMD) model. It is found that there exists a strong relationship between nuclear stopping and the ratio of different direction kinetic energy, and nuclear stopping can be replaced by the square root of the ratio of perpendicular and parallel total kinetic energy of fragments, and it can be used to extract information of isospin dependent in medium nucleon nucleon cross section. This physical quantity can be easily measured in nuclear reaction experiments, and it is a better probe.     

核子-核子碰撞截面对同位素标度参数α的同位旋效应

对两对重离子中心碰撞系统40C 40ca和60ca 40Ca以及112Sn 112Sn和124Sn 124Sn反应中就同位素标度参数n对于核子一核子碰撞截面的同位旋效应进行了研究.计算结果表明a对同位旋相关核子.核子碰撞截面amedNN(am)相对于同位旋无关核子一核子碰撞截面口aNN(am)的同位旋效应很明显,然而a对amedNN(am)相对于同化旋无关核子-核子碰撞截面a2nn(am)的同位旋效应是较小的.对以上两种条件下a同位旋效应的机理进行了仔细研究.     

核反应总截面参数化计算

给出了一个计算核反应总截面的参数化公式.用此公式计算了包括低能、中高能区大量系统的核反应总截面,且和实验数据进行了比较.讨论了反应总截面σ_R与中子过剩自由度(N-Z)的关系,以及相互作用半径R与轰击能量E_cm的关系.     

在非相对论能量下介质中的核子－核子碰撞截面

在非相对论能量下，采用Ｓｋｙｒｍｅ有效相互作用，计算了在核介质中的核子－核子（Ｎ－Ｎ）碰撞截面，研究了它与能量及密度的依赖关系，以及不同Ｓｋｙｒｍｅ参数对所计算截面的影响．发现在低密度时，介质中的核子－核子碰撞截面大于经Ｐａｕｌｉ修正后的自由核子一核子碰撞截面．而当高密度时，总会在高于某一能量以后，介质中的Ｎ－Ｎ碰撞截面大于经Ｐａｕｌｉ修正后的自由Ｎ－Ｎ碰撞截面．     

在非相对论能量下介质中的核子–核子碰撞截面

在非相对论能量下,采用Skyrme有效相互作用,计算了在核介质中的核子-核子(N-N)碰撞截面,研究了它与能量及密度的依赖关系,以及不同Skyrme参数对所计算截面的影响.发现在低密度时,介质中的核子-核子碰撞截面大于经Pauli修正后的自由核子一核子碰撞截面.而当高密度时,总会在高于某一能量以后,介质中的N-N碰撞截面大于经Pauli修正后的自由N-N碰撞截面.     

中能重离子碰撞中同位旋相关核子-核子碰撞截面和同位旋相关平均场的探针

在最近几年我们通过使用同位旋相关的量子分子动力学模型 (IQMD)系统的研究了同位旋相关的平均场和介质中核子 核子 (N N)碰撞截面对中能重离子碰撞 (HIC)中碎裂和耗散的同位旋效应。我们发现原子核阻止R和Qzz,中等质量碎片多重性Nimf和质子(中子 )发射数Np(Nn)敏感的依赖于介质中N N碰撞截面的同位旋效应 ,而弱的依赖于同位旋相关的平均场 (对称势 ) ,这些物理量作为提取相对高能范围缺中子系统的同位旋相关介质中N N碰撞截面的探针。我们也可以通过相对低能区到 1 5 0MeV/u的前平衡核子发射中质比来提取关于对称势的知识和讨论它的同位旋依赖性。     

Total Hadronic Cross Sections

<正>(Updated September 2013,COMPAS group,fflEP,Protvino)This updated version of the total hadronic cross sections review is based on the first half of 2013 update of the database for total cross section and the ratio of the real-to-imaginary parts of the forward elastic scattering hadronic amplitudes.New data on total pp coUisions cross sections from CERN-LHC-TOTEM[1]and new data from cosmic rays experiment PAO[2]were added.We use a procedure for ranking models as described in[3]to identify the safest parameterizations for extrapolations.Incidentally,the models giving the best fit of accelerator data also reproduce the experimental cosmic ray nucleon-nucleon data extracted from nucleon-air data with no     

双光子过程中的跃迁截面

重新检验了双光子过程中跃迁截面的概念：当密度矩阵中对角元随时间的变化缓慢时，速率方程和相关的跃迁截面是很好的近似。导出速率系数的表达式：在强光场中描述单光子过程中的系数要作很大的修改，而描述双光子过程的系数可从单光子过程的系数导出。激光场的功率分配的最佳化随总功率的强度而激烈变化。当有多个能级或多个激光模式的干涉效应时，利用跃迁截面的计算比直接利用布洛赫方程的计算还要复杂。     

17C反应截面和去中子截面

利用日本理化学研究所的放射性束流线RIPS, 测量了能量为79A MeV的¹⁷C在¹²C反应靶上的反应截面, 并同时得到了¹⁷C的移去1个、2个及3个中子的截面; 分别利用有限力程Glauber模型和少体Glauber模型结合壳模型的谱因子分析了反应截面和移去1个中子截面, 研究了¹⁷C的密度分布、结构和价中子布居. 反应截面和中子移去截面是两个相互独立的量, 通过对两者的分析, 都可以得出¹⁷C由芯核¹⁶C和价中子组成, 并且价中子主要处于d_5/2轨道的结论. 总结了现有的碳同位素的反应截面和相互作用截面的工作.     

Pseudo-Finsleroid Corrections to Electron Scattering Cross Sections

Consideration of quantum field theory in the pseudo-Finsleroid space leads to the occurrence of corrections to expressions for scattering cross sections of interacting particles. Such corrections are presented for certain elementary processes. The calculation method is based on the proper generalization of the S-matrix, T-product, and the Green's functions. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 52–58, August, 2005.     

Reduction Methods for Total Reaction Cross Sections

The most frequently used methods to reduce fusion and total reaction excitation functions were investigated in a very recent paper Canto et al. (Phys Rev C 92:014626, 2015). These methods are widely used to eliminate the influence of masses and charges in comparisons of cross sections for weakly bound and tightly bound systems. This study reached two main conclusions. The first is that the fusion function method is the most successful procedure to reduce fusion cross sections. Applying this method to theoretical cross sections of single channel calculations, one obtains a system independent curve (the fusion function), that can be used as a benchmark to fusion data. The second conclusion was that none of the reduction methods available in the literature is able to provide a universal curve for total reaction cross sections. The reduced single channel cross sections keep a strong dependence of the atomic and mass numbers of the collision partners, except for systems in the same mass range. In the present work we pursue this problem further, applying the reduction methods to systems within a limited mass range. We show that, under these circumstances, the reduction of reaction data may be very useful.     

The Reaction Cross Section and Neutron Removal Cross Sections of 17C

The reaction cross section, together with the one-, two- and three neutron removal cross sections, of ¹⁷C with the energy of 79A MeV on carbon target were measured using the radioactive beam line RIPS of RIKEN. The reaction cross section and the one-neutron removal cross section were analyzed within the frame of Glauber model. Both the analyses favor the dominant configuration of a ¹⁶C core (2⁺) plus a d_5/2 valence neutron for ¹⁷C. The work for the neutron-rich carbon isotope on the reaction cross section σ_R and the interaction cross section σ_I on ^{12C target are summarized.}     

Investigations of Nonconventional Cross Sections of Gas-Discharge Lasers

Russian Physics Journal - Gains of lasers with regular polygon cross sections of tubes having curvilinear sections are considered. Calculations are performed for parabolic polygons, a triangle, and...     

Ba同位素的截面测量

用60MeV/u¹⁸O离子轰击天然铀靶,通过²³⁸U(¹⁸O,X)反应产生钡的放射性同位素.使用放射化学分离方法从被照射过的铀靶中分离出Ba,用HPGeγ射线探测器测量Ba样品的γ射线谱,经对所得时间累计谱的处理和分析得到了Ba同位素的产生截面,并观察到Ba同位素分布中的双峰分布现象.     

Fragmentation Cross Sections of 158 AGeV Pb Projectiles

We investigate the fragmentation cross sections of 158 AGeV ^207Pb projectile interacting with different targets using CR39 nuclear track detectors. The exposure is made at SPS beam facility of CERN. The detectors are chemically etched to obtain data in the form of etched cone length. The nuclear and electromagnetic contributions to the measured total charge-changing cross sections are investigated. The estimated results are compared with those found in the literature for similar research work.     

Calculations of Photo-Ionization Cross Sections for Lithium Atoms

Photo-ionization cross sections for the ground and the ≤5 excited states of lithium atoms are calculated in the photoelectron energy ranging from threshold to 0.5 Rydberg. The wavefunctions for both the bound and continuum states are obtained by solving the SchrSdinger equation numerically in a symplectic scheme. Our results are in excellent agreement with the recent experimental measurements and in harmony with other theoretical calculations.