Be9(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Be⁹(d,p₀)Be¹⁰(0),Be⁹(d,p₁)Be¹⁰(3.368MeV),Be⁹(d,t₀)Be⁸(0),Be⁹(d,α₀)Li⁷(0)及Be⁹(d,α₁)Li⁷(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Be⁹(d,p₀)Be¹⁰的激发函数。在θ_L=135°和112.5°,E_d=1.2MeV,用较厚靶(100—300μg/cm²)测量了Be⁹(d,p₀)Be¹⁰(0)反应的截面绝对值,结果为σ_(p0)(θ_L=135°)=1.60mb/sr,σ_(p0)(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。     

高能正负电子对的湮没与超窄共振ψ粒子的作用

本文给出了R=(σ(e⁺e^-→强子))/(σ(e⁺e^-→μ⁺μ^-))随能量上涨的一个解释。研究了新发现ψ粒子所具有作用的性质,指出其强度f²/(4π)～10^-5—10^-6。求得峰值截面σ₀=(12π)/m_ψ²(Γ(ψ→e⁺e     

BeCl分子电子激发态的多参考组态相互作用计算

运用含Davidson修正的多参考组态相互作用方法,在aug-cc-pVTZ基组水平上,对BeCl分子基态和相同多重度的几个低电子激发态进行了势能扫描计算.通过群论原理确定各电子态对称性及离解极限.将其中基态(X²Σ⁺)和第一激发态(A²Π})对应的势能曲线拟合到Murrell-Sorbie解析势能函数形式,得到基态(X²Σ⁺)的离解能及主要光谱常数(括号中为文献[6]提供的实验值)为D_e=3.74eV,R_e=0.18173nm(0.17970),w_e=857.4cm¹(847.2),w_ex_e=5.03cm^-1(5.14),B_e=0.7103cm^-1(0.7285),α_e=0.0059cm^-1(0.0069),第一激发态(A²Π)的D_e=3.02eV,R_e=0.18369nm(0.18211),w_e=832.7cm^-1(822.1),w_ex_e=5.93cm^-1(5.24),B_e=0.6953cm^-1(0.7094),α_e=0.0065cm^-1(0.0068),计算结果与实验值符合得较好.另外,通过Level程序求解双原子径向核运动的Schrödinger方程得到J=0时BeCl分子这两个电子态的全部振动能级.     

7Li2(X1Σ+g)分子的振动能级、转动惯量及离心畸变常数

使用密度泛函理论B3LYP和B3P86，以及组态相互作用方法CCSD(T)和QCISD, 利用多个基组对⁷Li₂(X¹Σ⁺_g)分子的平衡核间距(R_e)、谐振频率(ω_e)和离解能(D_e)进行了计算, 发现在CCSD(T)/cc-PVQZ理论水平下得到的结果(R_{e相似文献}   

中子相对论唯象光学势与相对论微观光学势

用计算机自动调参数方法,通过最佳符合¹²C到²³⁸U十个核素在入射中子能量E_n=20—1000MeV的全截面σ_t,去弹截面σ_non和弹性散射角分布σ_el(θ),得到了一套普适相对论唯象光学势(RPOP).同时,用基于Walecka模型的相对论微观光学势(RMOP)分析了同样的数据.通过对两种相对论光学势的比较,给出了对它们进行改进的方向.     

e+e－→J/ψ→γB,B→P1P2的角分布和玻色子B的自旋分析

本文给出了过程e⁺e^－→J/ψ→γB,B→P₁P₂的螺旋性形式(HF)^[1]和等效相互作用形式(EIF)^[2]之间的关系.在B的不同自旋(J=2,4)下赝标介子的角分布显示,为了确定B的自旋,存在敏感区域和不敏感区域.令人遗憾的是,θ/f₂(1720)和ξ(2230)的数据正好掉入不敏感区域.     

高能散射与αqRegge轨迹

我们引进一个具有真空量子数的新的Regge轨迹α_q,α_q(0)=α_p(0)=1,但α′_q(0)≠α′_p(0)。在高能非交换过程中α_q和α_p同时参与贡献且相互干涉,其结果和一个等效的Regge轨迹α_e相当,唯α_e的斜率α′_e(0)与过程有关,这与单一α_p轨迹的结论有本质的区别。根据我们的看法,由不同过程测得的α′_e(0)将有不同数值,这点和最近的实验是相容的,并且预期将来K-N散射所测的α′_e(0)亦将另取他值。α_q轨迹的存在将不改变高能相关过程总截面的关系,但使高能核子极化度随能量增大较缓慢地衰减。     

四态叠加多模叠加态光场|Ψe(4),Ⅲ〉q的等阶N次方Y压缩

根据量子力学的线性叠加原理,构造了由多模偶相干态与多模虚偶相干态组成的第Ⅲ种四态叠加多模叠加态光场态|Ψ_e⁽⁴⁾,Ⅲ〉_q的等阶N次方Y压缩特性.结果发现:1) 当压缩阶数N=4m,(m=1,2,3,…)时,态|Ψ_e⁽⁴⁾,Ⅲ〉_q恒处于等阶数N-Y最小测不准态;2) 当压缩阶数N=4m′+2,(m′=0,1,2,…)时,在(θ₁-θ₂),q,R_j,r₁,r₂等取不同的组合定值下,态|Ψ_e⁽⁴⁾,Ⅲ〉_q可分别呈现出等阶N次方Y压缩效应与"半相干态"效应;3) 当压缩阶数N为奇数时,在(θ₁-θ₂),q,R_j,r₁,r₂等取不同的组合定值下,态|Ψ_e⁽⁴⁾,Ⅲ〉_q可呈现出等阶N次方Y压缩效应.     

原子的解析波函数

我们设计了一套变分波函数,用来计算了周期表中前面十个原子的能量。我们设计的单电子试探波函数具有下列形式:1s:ψ₁(r)=N₁e^-μαr[1+(μbr)²], 2s:ψ₂(r)=N₂[(μr)e^-μr-Ne^-μcr], 2p:ψ₃(r)=N₃(μdr)cosθe^-μdr, ψ₄(r)=N₄(μdr)sinθe^iφ-μdr, ψ₅(r)=N₅(μdr)sinθe^-iφ-μdr。式中的a,b,c,d及μ为五个变分参数。N₁,N₂,N₃,N₄与N₅为归一化因子;N由ψ₁与ψ₂的正交条件来决定。用这种波函数来计算原子的能量,所得的结果比莫尔斯等人(P.M.Morse,L.A.Young and E.S.Haurwitz)用他们设计的四参数波函数所算得的结果为好,更接近实验值,同时也接近于由自洽场所算出的结果。若我们的波函数中固定c等于1不变,这时就变为只有四个参数的波函数,结果仍比莫尔斯等人的好。     

e++e－→J/ψ→V+X,X→3P过程的角分布螺旋度形式

本文给出了过程e⁺+e^－→J/ψ→V+X,X→P₁+P₂+P₃(V和P_i分别代表矢量介子和赝标介子)的角分布螺旋度形式,为确定上述过程中间态X的自旋和宇称提供了理论公式.     

Raman spectra of GdS,GdSe, GdTe and LaTe: Phonon density of states in fcc metals

The Raman spectra of the fcc metals GdS, GdSe, GdTe and LaTe were measured. A defect induced first order scattering mechanism is dominant with the scattering spectra representing the one phonon density of states. Spin dependent Raman scattering was not found.     

Barrier distributions derived from quasielastic backscattering of 48Ti, 54Cr, 56Fe, 64Ni, and 70Zn projectiles on a 208Pb target

In order to study the nucleus-nucleus interaction in Pb-based cold fusion, we have measured excitation functions for quasielastic scattering of 48Ti, 54Cr, 56Fe, 64Ni, and 70Zn projectiles on a 208Pb target at backward angles. The barrier distributions were derived from the first derivative of measured quasielastic scattering cross sections relative to the Rutherford scattering cross section. The centroids of the barrier distributions show a deviation from several predicted barrier heights toward the low energy side. The shape of the barrier distributions is well reproduced by the results of a coupled-channel calculation taking account of the coupling effects of two phonon excitations of the quadrupole vibration for the projectiles and of the octupole vibration for the 208Pb target.     

Nano-metrology of porous structures — I Comparison of measured neutron scattering with calculated scattering to access pore lattice,diameter, and wall parameters,using models of extended arrays of regular or randomised pores

Neutron scattering offers a length-scale-independent method of probing structured matter on an atomic scale through nano-scale to meso-scale. A protocol is presented that provides a versatile method of determining structure, by comparison of measured and calculated neutron scattering, for any structural distribution that can be described algebraically or numerically, requiring no particular model other than the model of the structure, and needing no adjustable parameters other than the scale and other parameters describing the physical model. The method enables the direct comparison of measured and calculated scattering from structured matter: from simple finite and infinite bodies, from extended regular array of pores, or from extended arrays of pores with a partially randomised character. Examples are given for the radial distributions of a range of regular bodies, of large arrays of highly ordered porous materials such as templated SBA-15 and MCM-41 silicas, as well as for more disordered materials such as sol–gel silicas. Monte Carlo integration of the calculated scattering for ensembles of up to about 100,000 pores has been studied using these techniques. The method enables the calculation of the solid–solid density correlation function G(r)$G\left(r\right)$ for model systems, and hence, by Fourier transformation, the expected scattering. Example measured scattering is compared with the calculated scattering, with further data presented in a related paper. The technique allows the direct calculation and comparison with measurement of all three of the main pore structural parameters: lattice spacing, pore diameter, and pore-wall thickness. Example SBA-15 wide and small angle neutron scattering (SANS) data, measured on NIMROD (the Near and InterMediate Range Order Diffractometer at ISIS), is used as an initial evaluation of the applicability of the techniques. The method is also applicable to determining structure by comparing calculating with measured diffraction broadening, and an example is given using SBA-15 diffraction data, measured on D20, at the Institut Laue-Langevin (ILL), Grenoble.     

ELASTIC SCATTERING OF FAST NEUTRONS FROM Fe,Cu AND Pb

Using time of flight technique the elastic differential cross sections were measured for neutrons from natural Fe, Cu, and Pb in the energy range 1.10 to 1.40 MeV.The effect of neutron attenuation and multiple scattering in the sample is corrected by extrapolation of the experimental results. The correction of scattering angles due to the finite source-sample-detector geometry is also considered. The measured elastic differential cross sections are expressed by Legendre polynomial expansions, from which the total cross sections are obtained.The Optical-Model Calculations are carried out which show a reasonable consistency with the measured values.     

Neutron scattering from Au,Hg, and Tl

The elastic and the inelastic scattering of fast neutrons from Au, Hg, and Tl was studied at incident neutron energy intervals of ~50 keV from 0.3 to 1.5 MeV. The differential elastic scattering cross sections were determined approximately every fifteen degrees from 20 to 145 degrees. The cross sections for the inelastic excitation of states in Au at 77, 270, 409, 520, 540, 740, 830, 940, 1120, and 1220 keV; in Hg at 160, 208, 440, 610, 980, and 1120 keV; and in Tl at 205, 279, 615, 680, 930, and 1080 keV were determined. The measured elastic scattering cross sections were compared with the results of optical model calculations and evidence for a decrease in the imaginary part of the potential near the doubly closed shell atA=208 was observed. The results of Hauser-Feshbach calculations, utilizing known spin and parity assignments together with those estimated from nuclear systematics, were in qualitative agreement with the measured inelastic excitation functions. The effect of resonance width fluctuations was considered in the context of the experimental results.     

Rayleigh scattering cross sections of combustion species at 266, 355, and 532 nm for thermometry applications

Rayleigh scattering cross sections are measured for nine combustion species (Ar, N2, O2, CO2, CO, H2, H2O, CH4, and C3H8) at wavelengths of 266, 355, and 532 nm and at temperatures ranging from 295 to 1525 K. Experimental results show that, as laser wavelengths become shorter, polarization effects become important and the depolarization ratio of the combustion species must be accounted for in the calculation of the Rayleigh scattering cross section. Temperature effects on the scattering cross section are also measured. Only a small temperature dependence is measured for cross sections at 355 nm, resulting in a 2-8% increase in cross section at temperatures of 1500 K. This temperature dependence increases slightly for measurements at 266 nm, resulting in a 5-11% increase in cross sections at temperatures of 1450 K.     

Elastic proton scattering from He in the forward direction at 200, 350 and 500 MeV

The differential cross section for the elastic scattering of protons from ⁴He has been measured at 200, 350, and 500 MeV over an angular range from 3.5° to 15° in the lab system. In addition, the analyzing power was measured in the same angular range at 350 and 500 MeV. The experiment makes use of a tenuous gas target in which the recoil -energy is measured with solid-state detectors. The proton scattering angle is measured outside the target by a system of multi-wire proportional counters. The differential cross sections have a nearly exponential dependence on momentum transfer in this kinematic range and grow with increasing energy. The analyzing power shows strong positive asymmetry.     

Measurement of spin-correlation parameters ANN,ASS, and ASL at 2.1 GeV in proton-proton elastic scattering

At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.     

Elastic backward scattering of positive pions from 12C at 23, 29 and 35 MeV

The elastic scattering of positively charged pions at 23, 29 and 35 MeV scattering from ¹²C has been measured at 161°, 168° and 176° scattering angles. The new measurements give a backward descending behaviour to the existing angular distribution at 30 MeV. The complete angular distribution is compared to a calculation based upon the only Ericson-Ericson-Lorentz-Lorenz effect and to the theoretical models of Landau and Thomas and of Stricker et al. for low-energy pion-nucleus scattering.     

Acoustic dissipation and density of states in liquid, supercooled, and glassy glycerol

Combined Brillouin spectra collected at visible, ultraviolet, and x-ray frequencies are used to reconstruct the imaginary part of the acoustic compliance J' over a wide frequency range between 0.5 GHz and 5 THz. For liquid, supercooled, and glassy glycerol, J' is found to be linearly dependent on the tagged-particle susceptibility measured by incoherent neutron scattering up to ?1 THz, giving evidence of a clear relation between acoustic power dissipation and density of states. A simple but general formalism is presented to quantitatively explain this relation, thus clarifying the connection between the quasielastic component observed in neutron scattering experiments and the fast relaxation dynamics probed by Brillouin scattering.