极化(e,2e)碰撞电离的研究进展

传统（ｅ,２ｅ）谱学已成为研究原子和分子电子结构和电离机制的强有力工具之一,本文首先简要回顾了迄今国内外传统（ｅ,２ｅ）谱学研究的历史和现状。然后,再重点介绍近几年开展极化（ｅ,２ｅ）碰撞电离研究的进展。     

极化（e,2e）碰撞电离的研究进展

传统（ｅ，２ｅ）谱学已成为研究原子和分子电子结构和电离机制的强有力工具之一，本文首先简要回顾了迄今国内外传统（ｅ，２ｅ）谱学研究的历史和现状。然后，再重点介绍近几年开展极化（ｅ，２ｅ）碰撞电离研究的进展。     

（e,2e）反应的多重散射理论

将文献［８］发展的（ｅ，２ｅ）反应多重散射理论推广到更一般的情况，去掉不动点近似。用得到的波函数进行了计算，并与文献［９］的结果做了比较。     

低能（e,2e）反应中的卢瑟福散射效应

以入射能量为６４．６ｅＶ、能量均分、共面不对称几何条件下Ｈｅ原子电子碰撞电离过程为例,分析低能（ｅ,２ｅ）反应中的碰撞机制、交换效应和卢瑟福散射效应,揭示了两种新的碰撞机制（ＤＢ碰撞和ＴＢ碰撞）的物理实质。     

共面双对称几何中Li^＋（1s^2）（e,2e）反应的理论研究

利用Ｂｅｒａｋｄａｒ理论,考虑了入射道的库仑相互作用,在共面双对称碰撞几何中,计算了能量为２５１ｅＶ入射电子碰撞Ｌｉ＋（１ｓ２）（ｅ,２ｅ）反应的三重微分截面（ＴＤＣＳ）,讨论了不同散射振幅对截面的贡献,分析了干涉效应及入射道库仑场对截面的影响．结果表明,它们对决定ＴＤＣＳ的角度分布和大小起着重要作用．     

低能（e,2e）反应角度分布的靶依赖

利用ＢＢＫ波函数及Ｂｅｒａｋｄａｒ和Ｂｒｉｇｇｓ对其Ｓｏｍｍｅｒｆｅｌｄ参数的修正结果（即考虑第三个粒子存在对两个粒子间相互作用的影响），考虑了入射道的库仑相互作用及出射粒子的交换对称性，计算了在共面－等能－共线几何情况下，低能（超出电离阈能４ｅＶ）电子碰撞Ｈｅ＋，Ｌｉ＋（ｅ，２ｅ）反应绝对三重微分截面，结果表明，入射道库仑场对其向前和向后散射的ＴＤＣＳ影响较大。     

原子（e,2e）反应中跃迁矩阵元的解析处理方法

提出了一种研究原子（ｅ，２ｅ）反应动力学中跃迁矩阵元的计算方案。通过引入因子１／ｒ１２和ｅ－λｒ的付立叶变换及Ｆｅｙｎｍａｎ参数积分技术，将包括三个库仑波、两粒子相互作用项和原子束缚态轨道波函数的被积函数，在两粒子坐标空间下的六重积分解析地约化为实空间下的二重积分。     

Cd_xHg_（1－x）Te／SiO_2固溶体微晶掺杂玻璃三阶非线性光学性质的

本文首次报道了对采用溶胶凝胶和原位生长工艺制备的Ｃｄ_ｘＨｇ_(１－ｘ)Ｔｅ／ＳｉＯ_２固溶体微品掺杂玻璃进行的三阶非线性光学性质实验研究及其结果。利用回返式简并四波混频技术，测得该固溶体掺杂玻璃的三阶非线性极化率的值为１０￣（－１２）ｅｓｕ量级。此结果比纯ＳｉＯ_２基体提高了２个数量级。表明该固溶体掺杂玻璃三阶非线性明显增强，在同样条件下，测得ＣＳ_２的三阶非线性极化率ｘ（３）为（１．７±０．２）×１０￣(－１２)ｅｓｕ，与国际上报道完全一致。     

自旋极化电子原子散射的(e,eγ)符合实验研究

本文介绍了自旋极化电子原子散射的(e,eγ)符合实验的理论基础、实验装置和参数测量方法,描述了符合实验研究主要结果,说明了符合实验研究的物理意义。     

自旋极化电子原子散射的(e,eγ)符合实验研究

本文介绍了自旋极化电子原子散射的(e,eγ)符合实验的理论基础、实验装置和参数测量方法,描述了符合实验研究主要结果,说明了符合实验研究的物理意义。     

Magnetic and orbital dichroism in (e,2e) ionization of sodium

We present the first measurement of (e,2e) ionization cross sections for a laser oriented atomic target by spin polarized electrons. Cross sections are presented as a function of target orientation and polarization direction of the incident electron beam. This study provides insight into mechanisms by which angular momentum is transferred from the valence electron to the two final-state continuum electrons in both singlet and triplet spin channels, by comparing measurement with distorted wave Born approximation and the dynamically screened three Coulomb wave calculations.     

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.     

Production of an H(h; A) Boson and a Heavy Fermion Pair in Polarized e–e+-Collisions (I)

Russian Physics Journal - The process of production of an H (h; A) boson of the Minimal Supersymmetric Standard Model and a heavy fermion pair in arbitrarily polarized $$ {e}^{-}{e}^{+}\to...     

Measurements of the electric form factor of the neutron up to Q2=3.4 GeV2 using the reaction 3He(e,e'n)pp

The electric form factor of the neutron was determined from studies of the reaction 3He(e,e'n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find G(E)(n)=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q(2)=1.72, 2.48, and 3.41 GeV2, respectively.     

e+e-湮没中轻夸克碎裂为粲介子的研究

研究了e+e-湮没中"初始"轻夸克和胶子劈裂产生的组合为介子(包括D-, D-s, 0)或*介子(包括D*-, D*-s, *0)的过程.发现尤其在s=MZ处,其产额相对较大,当限制或*的能量大于20GeV时,它和c夸克碎裂产物的不变质量谱在稍大于2M附近有一个峰,这是该过程区别于其它或*介子产生过程的显著特征.此过程产生的矢量介子基本上是纵向极化的,与实验上观测到的*介子的纵向极化一致.     

Polarization and asymmetry of protons in an annihilation process e− + e+ → p + ¯p in the presence of weak neutral currents

The differential and total cross sections for annihilation of longitudinally polarized and transversely polarized electrons and positrons into pairs of longitudinally polarized protons and antiprotons are calculated in the center-of-mass system. The expressions obtained for the cross sections have electromagnetic, weak, and interference terms. It is shown that the existence of a weak current-current interaction (e) (¯pp) must lead for protons and antiprotons, emitted at an angle ®=90° to a nonzero degree of longitudinal polarization P(E) =1.3 and 36% for E=2.5 and 10 GeV and G=G_F=10^–5 M^–2,to the presence of forward-backward asymmetry in the angular distribution of the protons A(E)=1 and 12% for E=2.5 and 10 GeV (the asymmetry exists even when all the particles are unpolarized), and to other effects which are absent in the case of a pure electromagnetic interaction. It is shown that in experiments with polarized particles the contributions of different form factors can be distinguished and studied separately.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 93–100, January, 1974.We thank the participants in the seminars of Professor A. A. Sokolov and Professor Ya. P. Terletskii for discussions of the work.     

Measurement of the electric form factor of the neutron through d-->(e-->,e(')n)p at Q2 = 0.5 (GeV/c)(2)

We report the first measurement using a solid polarized target of the neutron electric form factor G(n)(E) via d-->(e-->,e(')n)p. G(n)(E) was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia ( 15ND3). The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility in quasifree kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find G(n)(E) = 0.04632+/-0.00616(stat)+/-0.00341(syst) at Q2 = 0.495 (GeV/c)(2).     

e08-008: Exclusive study of deuteron electrodisintegration near threshold

The study of threshold electrodisintegration of and elastic scattering on the only stable two nucleon system, the deuteron, can reveal specific aspects of the N-N interaction. The simplicity of electrodisintegration along with the simplicity of the deuteron makes this study most appropriate for revealing these interactions. By using an incident beam of polarized electrons and by measuring the polarization of the recoiling proton, the ratio of the electric (G _E ) and magnetic (G _M ) form factors for $d\left( {\vec e,e'\vec p} \right)$ (and $p\left( {\vec e,e'\vec p} \right)$ ) reactions may be extracted. This experiment was conducted in Hall A at Jefferson Lab in Newport News, Virginia using a beam of polarized electrons provided by the CEBAF Accelerator incident on a liquid deuterium (and hydrogen) target. The scattered electron and the recoiling (polarized) proton were detected using the High Resolution Spectrometers of Hall A. To determine the polarization of the recoil proton, an analyzing material was placed perpendicular to the protons trajectory through the spectrometer, in front of a set of straw chambers. Due to the spin-orbit interactions involved in the scattering of the proton from the analyzer material, asymmetries seen in the distribution of events detected by these straw chambers reveal the polarization of the recoil proton. By tracking the spin procession of the polarized protons from the straw chambers back to the target, the transferred and induced polarization of the proton may be determined. The (double-spin) asymmetries observed in the straw chambers will first be studied for the well-known elastic $p\left( {\vec e,e'\vec p} \right)$ process and compared to the asymmetries for $d\left( {\vec e,e'\vec p} \right)n\left( {x_B = 1} \right)$ . The analysis will then be repeated to determine how these asymmetries change with increasing x _B (to the kinematic limit for deuteron electrodisintegration).