1984 Vol. 8, No. 3
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A double core event with ΣEγ1000TeV observed in MEC is reported. The distributions of particles in the two cores are quite dissimilar from each other The possible existence of two different types of clusters is discussed.
The experimental results of charge division method with the self-quenching streamer pulses are reported. It is shown that the position resolution at the middle point of 2.5 m long tube can reach 3.3 mm even the signals are sent to ADC module by 60 m long cable. It is much better than using the proportional pulses, and the non-linearity is less than 0.14% of 2.5 m full scale. Some other aspects, such as ADC gate width and selecting of the decoupling capacitor etc. are also discussed, they would provide some practical basis for the design of the sample and hold system in the gas sampling shower counter of the Beijing e+e－ collider spectrometer.
Using the spectrum of bremsstrahlung obtained by solving shower equation of electrons in matter and the differential cross section of photoproduction of pions in OPE approximation, we calculate by PDp-11/23 the pion yields results from 1.2 GeV electrons bombarding on different targets, Be, C, Al, Cu and Pt. The optimization is made for pion yields to find the optimistic production angle. In order to choose the thickness of the target, the curves of pion yields vs. Target thickness are given.
A model of grand unified theory based on SU(6) gauge group is proposed. It can accommodate two generations of ordinary fermions with V－A weak coupling and two generations of anomalous fermions with V+A weak coupling. In this model a new discrete symmetry is introduced which insures existence of fermions with lower masses when SU(6) gauge symmetry is spontaneously broken. We choose simple Higgs fields with appropriate vacuum expectation values so that the masses of anomalous fermions are heavier than those of ordinary fermions. This model also gives the same value of Weinberg angle, sin2θw=3/8, as in the usual SU(5) grand unified model at the grand unified scale.
In this paper the MIT bag model and wave Packet Method are used to calculate the width of the process π0→2γ It is found that mπ→0 is a good approximation. The results are consistent with PCAC. The theoretical value of Γ(π0→2γ) is 2.7 times of the experimental value. The deviation is mainly from the calculation of Fπ. It is also found that the deviation strongly depends on the equation and the boundary contion of the MIT bag model.
In this paper we calculate the width of the process J/ψ→γ+ pseudoglueball in perturbative QCD. It is shown that because of the mixture between η、η′ and ι(1440) there is a glueball component in η and η′and it is predominant in the processes J/ψ→γη and γη′. The ratio Γ(J/ψ→γη′)/Γ(J/ψ→γη) obtained in this calculation is bigger than other theoretical models and consistent with experimantal data.
Assignment of the two "twins" generations of fermions in a SO(12) 32-dimensional spinor representation and its conjugate representation is given. Mass spectrum of fermions and their Cabibbo angles are discussed. The assignment of the four generations of fermions in a 352-dimensional spinor-tensor representaion of SO(12) Without repetiton is briefly discussed.
The occupation renormalized Hartree-Fock single particle potential is extended to include the 'particle' state occupation. The exac solution of the occupation renormalized Hartree-Fock approximation and that of the Hartree-Fock approximation are calculated in Lipkin Model. It turns out that the RHF solution is more close to the exact one than the HF solution. The effect of occupation probability depends on the strength of the interaction of the two body term.
The key role of the colliding component in soft hadronic interactions is studied. The different colliding components are found to display quite different distributions for both effective energy and fragmentation baryon momentum. After the calculation of the resonance decay correction to these distributions, a principle and method, which can directly decide the colliding component according experimental data are given. The data now available seem to rule out valence quark and support constituent quark as colliding component.
In the framework of the MIT bag model and under Born-Oppenheimer approximation, the 1－－QQqq states and their mixing with QQ states are discussed, where Q=c, b; q=u, d, and both QQ and qq are colour singlets. The mixing is introduced through a coupling, constant. An approximate scaling law for hadronic transitions (QQ)′→(QQ)ππ could be obtained and the ratio of Γ(ψ′→4ππ) to Γ(Υ′→Υππ) could be compatible with the data if the coupling constant is flavour-independent. The mixing is dominated by QQqq states in which qq is a P-wave 0++ state and therefore the observed isotropic angular distribution of the pion in ψ′→ψππ and γ′→γππ can be well explained.
The question of the relationship between the frequencies of injector linac and storage ring is analysed, especially when sub-harmonic buncher is used. In that case, it seems to be necessary to keep the ratio of two frequencies of the linac and storage ring to be an integer. This question is discussed in detail in this paper from several points of view. As a result of the discussion, two suggestions to avoid the restriction on the frequency relationship are presented.
(a) In order to avoid the tedious calculation in RGM, a reduced RGM which omit the exchange effects of nuclear core is proposed starting from physic considerations (Briefly, this is called QRGM). For a three-cluster system A+(BC), if C is a double-closed cluster, the QRGM abandons the antisymmetric procedure and various exchange forces between nuclear core C and other two clusters, but it still retains those between other non-closed clusters. (b) According to this model, the general formulae of three-cluster system under single channel treatment are derived. (c) Using the QRGM to d+a system, the phase shifts and differential cross sections of elastic scattering processes are calculated and the results agree well to the experiment data. This shows essentially that the QRGM is simple and effective (It is worth mentioning that by using QRGM. The satisfactory results are also obtained in the study of three-cluster system n+6Li(d+a). We shall report this in another paper.) (d) The exchange effects in d+a scattering is discussed.
The effect of energy dependence (ED) of the G matrix on RPA is investigated. Using the Hamada-Johnston potential, we calculate the 1p-1h TDA spectra of 16O. The following four cases are considered: (1) every G matrix element is approximated by its on shell value, (2) ED of G is taken intoaccount rigorously, (3) the effect of self-screening (SC) is considered, but the G matrix elements are assumed on the energy shell, (4) both SC and ED of G are taken into account. It is found that ED of G indeed causes a substantial damping effect on the backward-propagating bubbles of RPA as suggested by Wu. Further, ED of G and SC work in the same direction to diminish the difference between the energy spectra calculated by TDA and RPA.
An analysis for various components included in the difference of angular momentum between excited and ground bands, i(ω), is done carefully. It is pointed out that, generally, i(ω) should read as i(ω)=iRAL(ω)+iPR(ω)+iSC(ω). And the i(ω). corresponding to s-band of the first backbanding in even-even nuclei is really not only the iRAL(ω). The various components in i(ω) corresponding to s-band for three typical nuclei 164Er, 188Hg and 156Er are estimated quantitatively and microscopicly by using cranked shell model. For well deformed nuclei, iRAL plays the dominant role, but the contribution of pairing reduction, iPR, can not be neglected. As for the soft nuclei like 188Hg, the contribution from shape changes, iSC, is very important. While for transitional nuclei as 156Er, both pairing reduction and shape changes will play substantial role.
The comparison between BMM and IBM is comprehensively discussed in the spirit of the transformation theory by using the generator coordinate method (GCM). Some differences existed between these two essentially equivalent models are pointed out on the phenomenological level, and the possibility of distinguishing them is briefly discussed.
In this paper the Hamiltonian model is used for studying the nuclear dynamics by taking both the one-body and two-body interaction mechanisms into account. On the basis of the Von Neuman equation the coupling between the collective motion and the single particle degrees of freedom is discussed. Thus, the equations obtained are physically transparent and easy for numerical computations. They may be useful for describing the dissipative process of the nuclear collective motion as well as the equilibration process of the intrinsic degrees of freedom.
A heavy-ion time-of-flight spectrometer has been constructed and operated successfully in our experiments. The trigger detector consists of a thin plastic scientillator foil located at the focus of a perabolic mirror which is coupled to a fast photomultiplier with high light collection efficiency. The time resolution obtained for the system is around 500ps. The mass resolution for A=12 elastically scattered 12C line is ~0.3.
A new method for calculating the 3-dimensional magnetic field is described. The modified scalar potential is used to reduce the order of the coupled equations in the comparison with the vector potential under the same node number.
The differential cross sections of the elastic scattering of near 1GeV proton on 40,42,44,48Ca, 48T, 58,60,62,64Ni, 90Zr and 208Pb are calculated by use of the method of the collective coordinate and high energy cluster scattering theory for the Wood-Saxon potential. The results are found to be in a good agreement with experimental data.
We have studied the registration characteristics of polycarbonate ChaoYang No.1 for 238U. The experimental range of 238U in it was determined. The relation between the energy of 238U and range and the relation between the energy and REL of 238U in it are calculated. The VT versus REL response, the charge resolution and the mass resolution for heavy charged particles are analysed and discussed.
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