几个(n,d),(n,t)和(n,n'α)反应截面的测量

本文报告了En～14MeV中子以²⁷Al(n,α)²⁴Na或⁹³Nb(n,2n)^92mNb反应截面为中子注量标准测得的⁹²Mo(n,d*)^91mNb,¹⁰⁶Cd(n,d*)¹⁰⁵Ag;⁵⁴Fe(n,t)^52m+gMn,⁵⁸Ni(n,t)⁵⁶Co;⁵¹V(n,n'α)⁴⁷Sc和⁹²Mo(n,n'α)⁸⁸Zr的反应截面.文中还列举了能收集到的数据以作比较,中子能量是用铌锆截面比法测定的.     

Cross Section Measurements for (n,d*)(n,t) and (n,n'α) Reactions

Cross sections for some (n,d*),(n,t) and (n,n'α)reactions have been measured by using the activation method relative to cross sections of ²⁷Al(n,α)²⁴Na or ⁹³Nb(n,2n)^92mNb reactions in neutron energies around 14MeV.In this paper some of the published cross section data have also been listed and compared with our results.The neutron energies were determined by the method of cross section ratios for the reactions of ⁹⁰Zr(n,2n) ^89m+gZr and ⁹³Nb(n,2n)^92mNb.     

Be(d,n)反应中子源能谱测量及应用

利用中子飞行时间技术和BC501A液体闪烁探测器的粒子分辨特性,测量了0°方向、20 MeV氘束轰击厚金属铍靶反应产生的中子源能谱,测量的中子能谱范围为0.7～25.0 MeV。在60°方向放置芪晶体闪烁探测器,由刻度好的BC501A液体闪烁探测器归一校正后,用于中子源强度监测。利用Be(d, n) 反应中子源,采用单粒子灵敏度标定方法,实验标定了0.75~15.75 MeV能量范围内的薄膜闪烁探测器中子能量响应曲线,实验结果与蒙特卡罗模拟计算结果在8%的不确定度范围内一致。     

Be(d,n)反应中子源能谱测量及应用

 利用中子飞行时间技术和BC501A液体闪烁探测器的粒子分辨特性,测量了0°方向、20 MeV氘束轰击厚金属铍靶反应产生的中子源能谱,测量的中子能谱范围为0.7～25.0 MeV。在60°方向放置芪晶体闪烁探测器,由刻度好的BC501A液体闪烁探测器归一校正后,用于中子源强度监测。利用Be(d, n) 反应中子源,采用单粒子灵敏度标定方法,实验标定了0.75~15.75 MeV能量范围内的薄膜闪烁探测器中子能量响应曲线,实验结果与蒙特卡罗模拟计算结果在8%的不确定度范围内一致。     

~(50,48,46)Ti的(n,p)(n,α)和~(58)Ni的(n,2n)(n,p)反应截面的测量

本文叙述了从13.50 MeV到14.81 MeV中子能区用活化法相对~(21)Al(n,α)~(24)Na的反应截面,对~(50)Ti(n,α)~(47)Ca、~(48)Ti(n,p)~(48)Sc、~(46)Ti(n,p)~(46)Sc、~(58)Ni(n,2n)~(57)Ni、~(58)Ni(n,p)~(58m+g)Co五个反应截面的测量。并将所得的结果和其他作者的结果进行了比较。     

几个(n,d~*),(n,t)和(n,n′α)反应截面的测量

本文报告了En～14MeV中子以~(27)Al(n,a)~(24)Na或~(93)Nb(n,2n)~(92m)Nb反应截面为中子注量标准测得的~(92)Mo(n,d~*)~(91m)Nb,~(106)Cd(n,d~*)~(105)Ag;~(54)Fe(n,t)~(25m+g)Mn,~(58)Ni(n,t)~(56)Co;~(51)V(n,n'a)~(47)Sc和~(92)Mo(n,n'a)~(88)Zr的反应截面。文中还列举了能收集蓟的数据以作比较,中子能量是用铌锆截面比法测定的。     

快中子(n,α)和(n,p)反应的研究

快中子核反应数据,不论对反应堆和聚变堆的设计,还是对核反应机制和核结构的研究及其理论的发展均有着重要的意义．由于屏栅电离室的诸多特点,被用于快中子核反应截面、能谱及双微分截面的测量．作为系统研究的一部分,利用屏栅电离室在北京大学４．５ＭＶ静电加速器上和在４～７ＭｅＶ能区内,对４０Ｃａ、６４Ｚｎ、５８Ｎｉ、５４Ｆｅ、３９Ｋ的（ｎ,α）反应进行了成功的测量,并对５８Ｎｉ的（ｎ,ｐ）反应进行了初步的测量．实验给出了反应中出射粒子的微分能谱、角分布和反应截面．从测量结果来看,在所测能区内,角分布大致是９０°对称的,说明在此能区复合核反应机制起主要作用．The study of the charged particle emission reactions induced by 3～7 MeV fast neutrons is of considerable interest for both nuclear applications and the understanding of basic nuclear problems. For its many merits, twin gridded ionization chamber is used in the studies of (n,α) and (n,p) reactions. As a part of systematic investigation, the (n,α) reactions for some nuclei, such as 40 Ca, 64 Zn, 58 Ni, 54 Fe, 39 K have been studied. Cross sections...     

Tensor Force Manifestations in ab Initio Study of the 2H(d, γ)4He, 2H(d, p)3H, and 2H(d, n)3He Reactions

The ²H(d, γ)⁴He capture reaction and the ²H(d, p)³H and ²H(d, n)³He transfer reactions at very low energies are studied in an extended microscopic cluster model with a realistic nucleon–nucleon force. Our results show that the tensor force in realistic interactions plays an essential and indispensable role to reproduce the very low-energy astrophysical S factor of these reactions.     

Tensor force manifestations in ab initio study of the 2H(d,γ)4He, 2H(d,p)3H, and 2H(d,n)3He reactions

The (2)H(d,p)(3)H, (2)H(d,n)(3)He, and (2)H(d,γ)(4)He reactions are studied at low energies in a multichannel ab initio model that takes into account the distortions of the nuclei. The internal wave functions of these nuclei are given by the stochastic variational method with the AV8' realistic interaction and a phenomenological three-body force included to reproduce the two-body thresholds. The obtained astrophysical S factors are all in very good agreement with the experiment. The most important channels for both transfer and radiative capture are identified by comparing to calculations with an effective central force. They are all found to dominate thanks to the tensor force.     

~(59)Co(n,p)~(59)Fe,~(59)Co(n,α)~(56)Mn,~(59)Co(n,2n)~(58)Co反应截面的测量

本实验用活化法测量了中子能量在12.8MeV到17.8MeV的~(59)Co(n,p)~(59)Fe,~(59)Co(n,α)~(56)Mn,~(59)Co(n,2n)~(58)Co三个反应道的反应截面值,实验的测量误差在3.3％—6.9％范围内. 本文还计算了反应截面测量误差的协方差矩阵,并将实验测量值与理论计算值进行了比较.另外,还对上述三个反应道的截面进行编评,给出了推荐的激发曲线.     

Determination of the reaction-matrix elements of the D(d,n)3He and D(d,p)3H reactions forE d ≤500 keV

All available data of the mirror fusion reactions D(d, n)³He and D(d, p)³H have been subjected to a new analysis in order to extract the matrix elements of all 16 transitions necessary for inclusion of alll2 waves. Their energy dependence was assumed to be governed solely by Coulomb penetrabilities. The Levenberg-Marquardt algorithm was used to fit all experimental data. The experimental data are reproduced satisfactorily. The results compare well with anR-matrix analysis and with refined resonating group calculations. No suppression of quintet entrance-state transitions and therefore no neutron suppression in polarized fusion can be derived from this analysis.This work was funded by the German Federal Ministers for Research and Technology (BMFT) under the contract numbers 06-OK-153 and 06-OK-272     

(n,n)-(2n, 0)碳纳米管异质结的扭转力学特性

相近直径的锯齿型和扶手椅型碳纳米管可以共轴组合形成5-7碳环交替出现的柱形对称异质结. 本文利用分子动力学方法研究了直径相近且等长锯齿型和扶手椅型碳纳米管形成的(n, n)-(2n, 0)结在扭转过程中的扭矩和轴向应力随扭转角度的变化规律以及应力传递过程. 研究发现, (n, n)-(2n, 0)结扭转应变在达弹性限度内不会产生轴向应力, 该效应对基于碳纳米管扭转特性的纳米振荡器件的设计具有重要意义.     

Nuclear structure studies of 125Te with (n,γ), (d,p) and (3He,α) reactions

Levels in ¹²⁵Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and (³He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin.     

Be~9(d,p),(d,t),(d,a)反应研究

本文在E_d=0.1—2.5MeV能量范围内,研究了Be~9(d,p_0)Be~(10)(0),Be~9(d,p_1)Be~(10)(3.368MeV),Be~9(d,t_0)Be~8(0),Be~9(d,α_0)Li~7(0)及Be~9(d,α_1)Li~7(0.478MeV)诸反应。在E_d=0.150,0.220,0.401,0.706,1.005,1.301,1.484,1.750,2.000,2.250和2.500MeV共十一个能量上分别测量了这五群出射粒子在θ_L=10—155°区间的角分布。在θ_L=135°,E_d=0.1—2.5MeV,在θ_L=95°,E_d=0.1—2.2MeV,和在θ_L=112.5°,E_d=0.5—2.5MeV测量了Be~9(d,p_0)Be~(10)的激发函数。在θ_L=135°和112.5°,E_d=1.2MeV,用较厚靶(100—300μg/cm~2)测量了Be~9(d,p_0)Be~(10)(0)反应的截面绝对值,结果为σ_p_0(θ_L=135°)=1.60mb/sr,σ_p_0(θ_L=112.5°)=1.55mb/sr。这样就得到了在此能区内,这五群出射粒子的截面情况。对所得结果进行了一些讨论。     

~(58)Ni(n,p),~(60)Ni(n,p),~(62)Ni(n,α)和~(54)Fe(n,p)反应截面的测量与评价

本实验用活化法测量了中子能量在13.60 MeV—17.77 MeV的~(58)Ni(n,p)~(58m+g)Co,~(60)Ni(n,p)~(60)Co和~(62)Ni(n,α)~(59)Fe三个反应道的反应截面值,并计算了反应截面测量误差的协方差矩阵。实验的测量误差在3％—7％范围内。本文还对上述三个反应截面及~(54)Fe(n,p)~(54)Mn反应截面进行了编译,推荐了从阈能到20MeV能区的激发曲线。     

Spectroscopy of 88Sr with the 87Sr(n, γ) and 87Sr(d,p) reactions

The γ-ray spectrum emitted after thermal neutron capture in ⁸⁷Sr was studied at the ILL high flux reactor with pair- and intrinsic Ge-spectrometers. 661 transitions were assigned to the reaction ⁸⁷Sr(n, γ)⁸⁸Sr and 205 of them were placed into a ⁸⁸Sr level scheme of 47 levels. This represents 88% of the observed intensity. The level energies were determined with a precision of better than 20 ppm; the neutron binding energy was determined as 11 112.69 (22) keV. To aid the analysis high resolution particle spectra of the reaction ⁸⁷Sr(d, p)⁸⁸Sr were measured at 20 MeV deuteron energy with the Munich Q3D spectrometer. 85 states were observed with this reaction. The data helped to establish newly found levels and to differentiate between primary and secondary transitions in the (n, γ) data. The observed level densities and primary transition strengths are compared with statistical model predictions and non-statistical effects are discussed.     

(n,p)和(n,α)激发函数半经验计算方法

在En≤20MeV的情况下,忽略了粒子的二次发射过程,认为复合系统的形成截面是能量相关的,得到了理论模型清晰、公式形式简单的半经验计算方法.在靶核23≤A≤209的范围内,利用大量(n,p)和(n,α)反应的截面实验数据对可调参数进行了研究,得到了参数对靶核的N和Z以及入射能量的依赖关系.对得到的参数做了定性的解释,利用普适参数对(n,p)和(n,α)反应的激发函数做了预言,预言值在其误差范围内与实验数据一致. To simplify the calculation, some assumptions are considered at present work. The preequilibrium emission is the first step in the equilibrium process, which is characterized by exciton n=3 and "never come back" are considered at the preequilibrium emission process; the proton and alpha emissions are only competed with the neutron emission, the second particle emission is neglected. A semiempirical method of the cross section for (n, p ) and (n, α) reactions were obtained on the basis of evaporatio...     

~(100)Mo(n,2n)~(99)Mo,~(96)Mo(n,p)~(96)Nb和~(92)Mo(n,α)~(89m+g)Zr反应截面测量

本文报告了在E_n=13.40—14.79MeV中子能区用活化法以~(27)Al(n,α)~(24)Na截面为中子注量标准测得的~(100)Mo(n,2n)~(99)Mo,~(96)Mo(n,p)~(96)Nb和~(92)Mo(n,α)~(89m+g)Zr的反应截面,中子能量是用铌锆截面比法测定的。文中将实验测量值与理论计算值进行了比较,还对上述三个反应的截面进行了编评,给出了推荐的激发曲线。