ELASTIC SCATTERING OF K± MESONS BY 40—48Ca AND THE ANALYSIS OF NEUTRON DISTRIBUTIONS

The differential cross sections of the elastic scattering of K^±on ^40—48Ca are calculated in the framework of eikonal approximation. The theoretical values obtained by using different parameters are compared. Through adjusting the parameters of the neutron distribution, the improvement of the coincidence between the theoretical values and the experimental data is arrived. The result shows that the r.m.s radius of the neutron distribution of ⁴⁰Ca is smaller than that of the proton. (about 0.15fm smaller) and the surface thickness of the neutron distribution of ⁴⁰Ca is thinner than that of proton. This is consistent with the results of computation made by H.F. method and agrees with the analysis of elastic scaatering of protons in the mediate energy on ⁴⁰Ca by other authors.     

AN/TAS——6热象夜瞄器

1982年年初,美军与 Kollsman 公司订立了一项合同,该公司为其生产5127具夜瞄器以及测试装置等辅助设备。其中的一部分用来装在“陶”和“龙”反坦克导弹系统上,其余作为夜间观察装置,型号为 AN/TAS—6,被称作远程夜间瞄准器(NODLR).全部夜视器件均采用热象通用组件。     

THE ANALYSIS OF RADIOACTIVE DECAY CURVES (Ⅰ) TWO-COMPONENT DECAY CURVES——INTRODUCTION OF A NON-CLASSICAL METHOD OF ANALYSIS

In present paper, a non-classical method ("λ" method) of analyzing the two-component radioactive decay curve was developed. The use of the relationship between the apparent decay constant λ(t) and the time t in fitting is to be distinguished from the use of the relationship between the total activity A(t) and t in fitting by the classical method ("A" method). In "λ" method, there are three unknowns while in "A" method there are four, thus the former is simpler than the latter.     

CONSTRUCTION OF AN OPTICAL TWEEZERS—CALCULATION AND EXPERIMENTS

We report the construction of an optical tweezers system and the results of the trapping and the moving of living algal cells. Experimental study on trapping polystyrene spheres demonstrates the effects of the system parameters on the trap. The trapping forces on dielectric spheres are calculated using Ashkin's ray-optics model. The result shows that an objective with higher numerical aperture can build a more stable trap along axial direction than an objective with lower numerical aperture, though their transverse trapping forces are on the same order.     

FORMATION AND EMISSION OF LIGHT PARTICLES IN FAST NEUTRON INDUCED REACTION——A UNIFIED COMPOUND PRE-EQUILIBRIUM MODEL(2)

For fast neutron-induced reactions for structural"materials by using the unified compound pre-equilibrium model, the light composite particles emissions have to be oaken into account properly. The mechanism of cluster fororation and emission was investigated. Estimated results with considering the secondary emission process were compared with experimental data.     

THEORETICAL ANALYSIS OF SCATTERING OF ULTRASONIC PULSES BY RIBBON-TYPE CRACKS IN SOLID——GENERAL SOLUTION

Scattering of elastic waves by obstacles of various shapes,especially those having sharp edges,is an important problem in NDE.The problem of scattering of a plane longitudinal or SV ultrasonicpulse in a solid,by a crack of finite width with free faces,is investigated in this paper by applyingdouble Laplace transforms and the generalized Wiener-Hopf technque.A solution in the Laplacedomain is obtained.An approximate form of this solution is then formulated neglecting the higher-order multiple scatterings,which can be inverted by the Cagniard-de Hoop method.The approximatesolution in the time-space domain gives the major features of scattering in the early time and henceof the near field.The result is readily shown in pictorial form. We have experimentally studied the corresponding scattered field in glass by the use of the photo-elastic visualizing technique,but the results are not included here,except for one photoelastic picturefor illustration.     

ACOUSTIC—GRAVITY WAVES CAUSED BY AN IMPULSIVE POINT SOURCE IN THE MIDDLE ATMOSPHERE

In this paper the results of acoustic-gravity wave(AGW)are presented for an impulsive point source inthe middle atmosphere.By virtue of general function theory,the Fourier transformation function is expandedat high frequency and low frequency,respectively.Then Row‘s results are extended from the specialcondition to the general one.When we have cleverly introduced an integral with the parameter,the factor(1/ω_0 t_0)can be obtained,which has a great physical meaning.The conclusion of this paper is as follows:(1)Under special condition the,only has been obtained by approaching ofRow‘s.In the present paper any approaching need not be made in obtaining the results.Besides thethe corrective factor is gained.The less t—α—t_0 is,the more the corrective effect is.(2)Theof formula(12)in Row’s must be corrected to bewhereαis a retardant time(3)(1/ω_0 t_0)~n indicates that when t_0 is greater the corrective effect is less.Also indicates it when T_c islonger the corrective effect is more.(i.e.the lower the     

RESEARCH AND TECHNICAL NOTES DIFFRACTION BY HALF SCREEN WITH FINITE ACOUSTIC IMPEDANCE——A MODIFICATION TO AN EMPIRICAL FORMULA

A modification to an existing empirical solution of diffraction by a half screen with a finite acous-tic impedance is proposed,giving the formula a more balanced form with better accuracy when thescreen is not opaque.This is obtained by intrcducing the transmission coefficient into the existingexpression which only includes the reflection coefficient.The improvement is verified by experiments.     

A FURTHER STUDY OF QUASI RESONATING GROUP METHOD—— ANALYSIS OF p+6Li ELASTIC SCATTERING

In this paper,the elastic scattering of p+⁶Li is studied by 3QRGM,a three-cluster RGM omitting the antisymmetrization with the nucleon in the double magic cluster.The main conclusion from studying the systems of p+⁶Li and n+⁶Li is the following:The clustering and exchange effects lower the phase shifts conspicuously.hence they are very important in the lower energy region.     

RIGHT TRANSLATION INVARIANT METRICS AND VARIATIONAL PRINCIPLES ON A PRINCIPAL BUNDLE——TREATED AS THE UNION OF SPACE-TIME AND AN INTERNAL SPACE

In this paper, we discuss how to assign a metric on a principal bundle and howto rewrite the variational principles for a particle and for matter fields in an inva-riant from on the bundle in the principal-bundle formulation of gauge theories. Weshow that the right-translation invariant metric on the bundle must contain quantitieswhich transform exactly as gauge potentials, thus providing a new formalism for gaugefields. And we formulate the variational principle for a particle moving in the gaugefield as follows: The particle moves along a horizontal geodesic on the principalbundle. Starting from this we derive the Wong's equations of motion. Moreover, we elucidate the physical view-point which treats the bundle space asthe union of space-time and the internal space. Advantages of this viewpoint for un-derstanding the essentialities of gauge transformations and gauge invariance and forestablishing unified theories of gravitation and gauge fields are also discussed.     

ANALYSIS OF SURFACE EXCITATION OF ELASTIC WAVE FIELD IN A HALF SPACE OF PIEZOELECTRIC CRYSTAL——GENERAL FORMULAE OF SURFACE EXCITATION OF ELASTIC WAVE FIELD

This paper developes the general theory of the surface excitation of elastic wave field in a halfspace of piezoelectric crystal for both free and metallized surfaces.It is shown that the general elas-tic wave field U is equal to the convolution of the generalized Green's functions G and the general-ized forces T, U = G Twhere symbol,expresses dot-product-convolution. The generalized Green's functions are independent of excitation conditions and only dependenton material parameters and orientation. For the piezoelectric crystal,not only a mechanical source distribution at the surface,but anelectrical source distribution can also excite the elastic wave fields.Complete expressions of thegeneralized forces representing mechanical and electrical source distribution respectively are given.Especially for the free surface,the surface electrical sources can be composed of the discontinuityof normal electric displacement at the surface,and of the discontinuity of the tangential electric fieldas well.