1－－QQqq态及其与QQ态的混合和强跃迁

本文从MIT口袋模型出发, 利用Born-Oppenheimer近似, 讨论11^－－P波QQqq态及其与QQ态的混合, 其中Q=c, b; q=u, d, 且QQ和qq都处于色单态. 在描述混合的耦合常数与味无关的假定下, 可以得到QQ激发态强跃迁过程(QQ)′→(QQ)ππ的一种近似标度性质, 所得到的ψ′→ψππ与Υ′→Υππ的宽度比也同实验基本符合. 上述混合的QQqq态中以0⁺⁺qq态为主, 由此可以解释实验观察到的ψ′→ψππ和γ′→γππ中的π的各向同性角分布.     

THE l-FORBIDDEN M1 TRANSITIONS AND EFFECTIVE g-FACTORS IN 40Ca±1 NUCLEI

The B (M1) value of the l-forbidden M1 transition of ⁴⁰Ca ±1 nuclei were calculatedwith the effective g-factors in ⁴⁰Ca region. The results give a explanation of strong l-forbidden M1 transitions of ³⁹K, ⁴¹K. A qualitative explanation for the reason of largedifference of B(M1) value of l-forbidden M1 transition between ³⁹K, ⁴¹K and ³⁹Ca, ⁴¹Cais given also.     

ON THE MESONIC MOLECULES (αp,μ－) AND (αp,2μ－)

ACQM is applied to study the μ^－-mesenic molecules (αp,μ^－) and (αp,2μ^－).It is found that the ground state X²Σ⁺ of (αp,2μ^－) is the repulsive one and the ground state X¹Σ⁺ of (αp,2μ^－) is a bound state with the equilibrium proton-proton separation R_e=0.0078bohr and the minimum energy E=－551.78a.u..     

π－核双电荷交换反应核谱因子和26Mg(π+, π－)26Si反应

π^－核双电荷交换反应的强度与反应过程的两核子转移的核谱振幅直接联系着. 本文讨论了这类反应与它们的核谱因子的关系. 并以²⁶Mg(π⁺, π^－)²⁶Si为例, 用两种核结构讨论了它的激发函数和微分截面. 我们所用的理论方法能够解释实验数据.     

MEASUREMENT AND ANALYSIS OF EMITTED α PARTICLES IN REACTIONS OF 12C BOMBARDING 12C,27Al AND natCa

The energy spectra and angular distributions of the emitted α particles in the reactions of the 69.5MeV ¹²C bombarding ¹²C,²⁷Al and ^natCa have been measured and analysed using the fast particle exciton model. The contribution from the equilibrium and preequilibrium α-emissions is calculated to be 89%, 81% and 83% of the total α yields for the three reactions respectively, where the preequilibrium α emissions are 11%, 14% and 16% respectively. A small contribution comes from the other reaction mechanism.     

π－π－ Bose-Einstein Correlation at AGS Energies

The study of Bose-Einstein correlations between two identical particles offers a powerful probe to the space-time evolution of ultrarelativistic nucleus collisions.We calculate the correlation function of π^－π^－ due to the four space-time and four-momentum distributions of π-at freeze-out in hadronic cascade simulation of ²⁸Si(14.6 A GeV/c)+Au reactions.The correlation function calculated by Fourier transformation method,the correlation function resulted from fullcalculation and the corresponding experimental correlation function agree each other very well.The above freeze-out configuration of π^－ is also used to calculate the root mean square length of π^－ source.These lengths are compared with the conventional fitted radius parameters of source.     

THE CROSS-SECTION MEASUREMENTS FOR 59Co(n,p)59Fe,59Co(n,α)56Mn AND 59Co(n,2n)58Co REACTIONS

The cross sections of ⁵⁹Co(n,p)⁵⁹Fe,⁵⁹Co(n,α)⁵⁶Mn AND ⁵⁹Co(n,2n)⁵⁸Co reactions have been measured at neutron energy region of 12.8MeV—17.8MeV by activation method.The coveriance matrix of measured errors was calculated,and the comparison between the values of measured and calculated using theory model was made.The evaluated excitation functions for the three reactions are given.     

790 MeV 136Xe轰击56Fe靶时产生的丰中子同位素54Ti,56V,57V,58Cr

用790MeV¹³⁶Xe轰击⁵⁶Fe靶,测量了类靶碎片的质量数和原子序数。探测且鉴定了四个丰中子同位素⁵⁴Ti,⁵⁶V,⁵⁷V,⁵⁸Cr。同时提供了⁵⁵Ti,⁵⁸V,⁵⁹Cr存在的可能性。使用西德重离子研究中心的磁谱仪和磁分析一起进行了飞行时间和ΔE-E测量,同位素鉴定是可靠的。     

STUDY OF THE MECHANISM OF 12C（d,d）12C AND 12C（d,p）13C* REACTIONS

A formalism for studying the interference between the direct reaction and the compound resonance processes is presented by the S-matrix theory; The mechanism of ¹²C（d, d） ¹²C, ¹²C（d, p₁） ¹³C* and ¹²C（d, p₂） ¹³C* reactions in the energy range E_d=1.63 MeV to 2.05 MeV is analysed.Te results show that: the interference between these two processes exists; and the quantitative relation between them is given. While the parameters of direct reactions and compound resonance processes, particularly for four resonance states with E_d=1.726, 1.767, 1.792 and 1.86 MeV are determined.     

Study of the νi13/2－1 band in 189Pt

High-spin levels of ^189Pt have been studied with the in-beam T-spectroscopy method via the ^176Yb（^18O,5n） reaction at the beam energies of 88 and 95 MeV. The previously known ＂vi-1 13/2 band has been confirmed, and its unfavored signature branch extended up to the 31/2^＋ state. Within the framework of the triaxial particle-rotor model, the vi-1 13/2 band is suggested to be associated with the 11/2[615] configuration, and to have triaxial deformation.     

Investigation of the [лh9/2vi13/2－1] 10－ Isomer in 206At

The high-spin states of ²⁰⁶At have been studied in the ¹⁹⁷An (¹²C, 3n)²⁰⁶At reaction at ¹²C energies from 60 to 80 MeV using technique of in-beam γ-ray spectroscopy. Measurements of Tray excitation functions, γ-γ-t coincidences, and y-ray angular distributions were performed. A level scheme for ²⁰⁶At, including a 10^－ isomer with a measured half-life of 908±400 ns, was established for the first the. The characteristics of the 10^－ isomers in doubly edd ²⁰⁶At nuclei were stressed.     

关于162,164Er,164,166Yb,168Hf诸核的回弯机制

通过对相邻奇A核转动带的回弯行为的分析,无法肯定^162,164Er,^164,166Yb,¹⁶⁸Hf诸核的回弯机制。本文利用HFB推转模型,计算了这些核的排列角动量i（ω）和回弯的临界角频率ω_c,探讨了阻塞效应的影响,通过和实验值的比较,确定了它们出现回弯均是由于一对i_13/2中子转动排列的结果。     

μ－ CAPTURE IN NUCLEI

Using the many-body field theory the problems of μ^－ captures in nuclei are systematically studied.Without ajustable parameter,calculations are performed for the total nuclear capture rates of muon for nuclei ranging from light to heavy ones.It shows that the renormalization due to the spin-isospin-dependent strong interaction and the muon binding in the μ^－ atom are essential for a thorough understanding of this type of weak interaction processes.     

Study of Stretched States Populated by 56,57Fe,59Co(α,d)58,59Co,61Ni Reactions

Spectra and angular distributions of the(α,d)reactions on ⁵⁶Fe ⁵⁷Fe and 59Co have been measured with the △E-E telescopic systems and Q3D magnetic spectrometer at a bombarding energy of 35MeV from the HI-13 Tandem,and analyzed with microscopic DWBA.Among the angular distributions of nine levels strongly populated by ⁵⁶Fe(α,d)⁵⁸Co reaction, the experimental data of 6.79MeV and 6.4MeV levels in ⁵⁸Co were analyzed and discussed. The highest stretched configuration (1g_9/2,1g_9/2)₉ was found and J^π=1⁺ of 6.4MeV level was determined for the first time. No isolated stretched states were observed by ⁵⁷Fe ⁵⁹Co(α,d)reactions.This probably means that the strength of the stretched configuration spreads on a number of states.     

12C+27Al,12C+209Bi和14N+Pb反应全熔合截面测量

本文叙述了用云母径迹探测器分别探测复合核蒸发余核和裂变碎片的实验,从而测出了¹²C+²⁷Al,¹²C+²⁰⁹Bi和¹⁴N+Pb反应的全熔合截面和激发函数.并用锐截止模型由全熔合截面导出了临界角动量.实验结果和当前有关的理论计算进行了比较,在实验误差范围内基本相符.     

16O(16O, 12C)20Ne α转移反应机制的研究

¹⁶O(¹⁶O, ¹²C)²⁰Ne反应微分截面中的振荡结构在核分子轨道理论框架下, 基于由共价道到离子道的α转移机制得到满意的解释.     

Restudies of Searching for 1+－ Exotic State

In order to convenience for the data analysis of BES some new relations which can be used to search for the 1^－₊ exotic state in J/ψ→ωX,X→KKπ have been obtained.How to search for the 1^－₊ exotic state in the three-step two-body hadronic decay process J/ψ→ωX,X→KK*,K*→Kπ is also discussed.     

重离子引起的单质子转移反应40Ar(11B, 10Be)41K

测量了50MeV的¹¹B束在40Ar上的弹性散射角分布和单质子转移反应⁴⁰Ar(¹¹B, ¹⁰Be)⁴¹K的微分截面. 用光学模型拟合了弹性散射截面. 用包含反冲效应的精确有限程扭曲波玻恩近似(EFR-DWBA)分析了微分截面, 提取了谱因子.     

A Study of the Processes of e+e－→e+e－,μ+μ－ at Large Angle and Measured Luminosities

Using the BES data collected at √S=4.03GeV.the QED processes of e⁺e^－→e⁺e^－,μ⁺μ^－ have been studied. Our measurements agree with the QED prediction,and luminosities obtained from these two final states are compatible at a level of 4%.The total integrated luminosity of 23.1pb^－1 was given for all data collected at this energy region from the calculation.     

Branching Ratios of J/ψ→π03(π+π－)

The decay mode of J/ψ→π⁰3(π⁺π^－) was studied very little before. There are no informations except branching ratios for this channel in PDG book which based on less than 0.2×10⁶J/ψ events of MARKⅠ. Now, BESⅠ has a data sample of 7.8×10⁶J/ψ events, we can make more accurate results than MARKⅠ. Total of 3290±43 J/ψ→π⁰3(π⁺π^－) events including 1275±86 J/ψ→ω²(π⁺π^－) events are selected. J/ψ→π⁰3(π⁺π^－) and J/ψ→ω²(π⁺π^－) events have been generated with MC simulition for calculating events selection efficiency. BESⅠ result is: Br(J/ψ→π⁰3(π⁺π^－))=(2.52±0.06±0.43)% and Br(J/ψ→π⁰3(π⁺π^－))=(1.31±0.09±0.21)%. Meanwhile, we studied the invariant mass of 4π and ωππ to find interesting signals. It seems that there is a peak at about 1.74GeV in the invarianat mass spectrum of 4π, and a enhancement was also found at about 1.9GeV in the invariant mass spectrum of ωππ. It is not clear whether they are from resonances or background. Therefore, more work in detail is still going on.