1984 Vol. 8, No. 6
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Some performances of an adjustable field drift chamber operated in the self-quenching streamer mode (SQS) have Been measured. The counting rate plateaus as a function of threshold and gas mixture, the efficiency, the spacil resolution, the relationship between drift distance and drift-time, the pulse heights in different drift distance and the transition characteristics from saturated avalanche to SQS-discharge mode are presented in this paper. The influences of the benzene vapor are also studied.
For the purpose of nucleus-nucleus interaction detection, a detector consisted of CR-39 plastic track detector sheets interlayered with aluminium plates was launched to 37 km height by balloon near Beijing and exposured in the high energy nucleus beam of primary cosmic rays for 10 hours. The obtained Fe-Al interaction cross section (Δz≥1) at energy region higher than 4GeV/N is 1.76±0.18b.
A systematic analysis of SO(2n)×S GUT models with discrete symmetry S is presented. It is found that SO(14)×S and SO(16)×S are the satisfactory gauge groups of flavor unification. In addition, SO(14)×S and SO(16)×S models are discussed in detail. Both of them can accommodate four generation light fermions and preserve the asymptotic freedom of SU(3).
The general formulation and Feynman rules of strong coupling expansion in σ model are derived. Then the reduction of strong couplig expansion formulation is investigated. Finally, using Pade-type extrapolation technique, a useful research about dealing with divergences is presented.
The effect of Synchrotron radiation on the transversal polarization of electrons is investigated. The higher order quantum corrections on spin-flip radiation probability due to the recoil of photon are derived by two approaches. The result reveals a decrease in final polarization and an increase in relaxation time.
The Isobar model of G.E.Brown et al. for π-nucleus scattering is extended to describe the (π, N) reactions at intermediate energies. The many-body effects are treated by using a phenomenological approximation. The influences of some factors upon the differential reaction cross sections are investigated. These include nonstatic correction, nucleon correlation wavefunction and distorted effect of the outgoing nucleon. The angular distributions of 3He(π－,n)2H reaction at 100—300MeV are calculated. The theoretical calculations are essentially consistent with experiments.
Adopting rigid projectile approximation, the elastic scattering differential cross section for α+α and α+Ca40 at high energies are calculated on the basis of Glauber's theory. The influence of different single particle density of He4 on elastic scattering is discussed. The calculated results show that the correlation in projectile is of the same importance as that in target.
The strength of π-nucleus double charge exchange reaction is related to the spectroscopic factor of two nucleon transfer. In this paper, the relationship between the reaction amplitude and the spectroscopic factors is discussed. As an example, two kinds of nuclear structure are used in discussing the excitation function and the differential cross section of 26Mg(π+, π－)26Si. It is shown that the theoretical method can explain the exprimental data.
In this paper, using the property of the local isomophism between the group SO(6) and SU(4), a set of physical bases of the three particles is derived. The bases are equivalent to the hyperspherical function bases.
Assuming that the intermediate system decayes with a statistical lifetime, the general behaviour of the threefold differential cross section d3σ/dZdEdθ in the dissipative collisions of 68MeV12C+27Al and 68.6MeV12C+40Ca system are analysed in the diffusion model framework. The lifetime of the intermediate system and the separation distance for the completely damped deep inelastic component are obtained. The calculated results and the experimental data of the angular distributions and Wilczynski plots are compared. The probable reasons of the differences between them are briefly disscused.
It is assumed that the initial exciton number n0 is statistical. The expression of the probability h(n0) for any probable n0 is given. The theoretical calculation results, including the energy spectra and the double differential cross sections, are obtained by weighted summation of the contributions coming from various probable n0. The agreement between experimental data and the theoretical results is quite well.
27Al and natCa target were bombarded by the Carbon beam at incident energy 69.5MeV. The reaction products were identified by ΔE-E telescope and the spectra of Li, Be, N, O elements were obtained.
The values of deformation parameter of emitted fragmente are between 0.28—0.44. Calculated energy of full damped fragments are in agreement with the experimental data. The average life-time of the system is about (4—6)×10－22S.
VMI model is used to analyse the ground band and superband of some nuclei. It is indicated that the angular momentum of the bandhead of superband of two-quasiparticle excitations should be I0≥8+.
A heavy ion reaction products identification setup, which consists of a time-offlight measurement system and a ΔE-E telescope, has been constructed. The time resolution of the setup was found to be 250 ps (FWHM) for the elastic scattered particles of (14N+Ni) reaction.
Using the N~λn and Er(I+2)/Er(I)~I plots, the latest experimental spectrum of the nucleus 15266Dy86 has been further analysed. It is point out that the ground band levels with I=8+ belong to deformed collective band. But values of deformation are less than that of well deformed nuclei. And those levels are more vibrational like than rotational. The hint of pairing disapperance in nuclei 167,169Yband 84Zr is also discussed.
A sample and hold circuit with 8-hit capacity to be used to drift chamber read out electronics is described. It's integral nonlinearity is better than 0.5% for input pulse with 0—4V amplitude. Sampling error is about 1% with acquisition time of 80 ns. The drop of recorded signal is less than 1% in retention time of 40 ms.
The knowledge of SU(3) single-link partition function is required in many calculations (such as the strong coupling expansion, the mean field and variational approximation, etc.) in lattice gauge field theory. We express the single-link partition functions for various sources in the form of a one-dimensional integral which can esily be carried out on computer. The application of these single-link partition functions in variational computation is discussed.
A model based on Pati-Salam-Sarkar's work is presented in which p→μ+η has a half chance to be the main mode of proton decay.
The possibility of constructing at a realistic SUSY GUT model by use of N=2 finite supersymmetric theory is discussed. We find that the spontaneous breaking of gauge symmetry and supersymmetry can be realized, but it is difficult to make the quarks and leptons to acquire small masses.
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