1983 Vol. 7, No. 6
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Construction and characteristics of a 1m×1m MWPC, which has 2500 anode and cathode wires totally, are described in detail.
This article briefly reviewed the EPR paradox and some hypothesises which were stimulated by the EPR paradox to make attempt on correction for quantum theory, such as Bohm-Aharonov hypothesis and local hidden-variable theory, especilly Bell’s inequality.A recent experiment which has been done by authors about the pelarization angular correlation of positronium annihilation into two photons was reported, the results coincided with quantum theory very satisfactorily, excluded the Bohm-Aharonov hypothesis, they were above the Bell’s upper limit for 4 standard deviations.
Light pulse shape, number of photoelectrons per unit energy and obtainable time resolution were studied with BGO scintillator coupled to a XP2020 photomultiplier and compared with the similar measurements on NaI(T1) and ST401 plastic scintillator. The photoelectron yield of BGO was measured typically to be equal to 687/MeV by single photon method. The BGO scintillation decay curve was studied and we found that it could be resolved into two main lifetime components τ1=60ns, τ2=310ns with relative intensities I1=9%, I2=86% respectively. The time resolution of the system with start channel NE111-XP2020 and stop channel 7×11×12mm3 BGOXP2020 is obtained as FWHM=0.70ns at energy window E≥1MeV with 60Co source.
To investigate the possibilities of the self-quenching streamer mode (SQS) and saturated avalanche mode (SA) as the sampling means in the gas shower sampling calorimeter, this article reports the systematic measurements on gas multiplication characteristics from the proportional region to SQS region under several different mixture proportions of argon + methene, argon+ethene, argon+isobutane and argon+carbon dioxide mixtures, it also presents Several SQS counting plateaus. It is shown that if the proportion of the quenching gas is above 50% we can get about 300—400 volts SQS optimum operation region, in which almost all of the SA signals transit to SQS mode and the second leap of the SQS amplitude have not-occured, this is a very promising region for sampling counters in gas sampling calorimeter.
Starting from the assumption of the instantaneous interaction and supposing that the effective couplings between the quark and the antiquark arc spin independent, an unified solution of the 3-dimensional wave functions of the mesons with the natural Jpc is obtained, where J can take all the possible values. This type of the solutions has only one independent space wave function, which satisfies a second order equation. In the heavy quark approximation, adopting the linear potential, the mass spectrum of the new and the old mesons can be roughly explained by the formula of the energy cigenvalue of this equation.
In this paper, We study the polarization effects in large transverse momentum prompt photon production in pp-γx and pp-γx. The asymmetries and the circular polarization of the photon for these processes are calculated. The results are discussed.
Possible proton decay modes in the SU(4)C×SU(2)L×SU(2)R unified gauge model are discussed. There are not proton decays if Higgs particles are not involved in the processes. The characteristics of the decay products make it plausible to distinguish this model from the standard SU(5) or SO(10) model.
In this paper the Σ-N interaction is studied from the view of the meson exchange. The Σ-N potentials are obtained by means of One-Boson Exchange Potentials and Two-Boson Exchange Potentials. The results are compared with the Λ-N potentials. There may be a bound state in the Σ-N system which has the isospin I=3/2 and the Spin S=0.
In this paper, the two dimensional Fokker-Planck Equation is exactly solved by means of the numerical method. The velocity distribution at the saddle point, the second moments of the coordinate and velocity, the time development of the nuclear fission rate are studied. The maximum of the fission rate at a certain viscosity is exhibited by studying the dependence of the fission rate on the nuclear viscosity.
A microscopic calculation of the collective spectra of the neutron configurations (closed shells)50 (d5/2g7/2s1/2d3/2h11/12)12 is made based on the Dyson representation of the interacting boson model (IBM). The effective nucleon-nucleon interaction consists of a pairing force, a quadrupole pairing force and a quadrupole-quadrupole force. The wave functions of the three-dimensional isotropic harmonic oscillator are used for one-particle states, but the one-particle energies are chosen empirically by refering to the data of Cd110. For a rater wide region of the values of the effective interaction strength parameters calculations are performed to determine microscopically the s, d bosons and the IBM Hamiltonian and to diagonalize the IBM Hamiltonian thus obtained and to analyze the effects of the three parts of the effective nucleonnucleon interaction. We find that for appropriate values of the strength parameters of the effective interaction the calculated vibrational spectrum is in agreement with the experimental data of Cd110 and that by adjusting these parameter it is possible to reflect imitatively the transition from vibrational states to rotational ones.
An energy criterion is given for the determination of fission scission point configuration. It is assumed that the splitting of the nucleus occures immediately, if the deformation energy decreases monotonously as the decreasing of the neck radius, with the shape of the nucleus kept essentially unchanged. Otherwise, the deformation of the nucleus will continue untill the above condition is met. With this criterion and a suitable shape parametrization, the post scission phenomena of neutron induced fission of 235U are studied in the statistical model (neutron energy 0—14MeV). The calculated average fragment kinetic energy, fragment mass and charge distributions agree well with the experimental results. No adjustable constants is introduced.
In this paper, general expressions for transformation coefficients between the symmetry basis and physical basis of di-hadron system under two representations used commonly (which are called L.S and jj representations) have been given. All coefficients for the Os state six-quark system with spin-isospin SU2×SU2 are carried out.
This paper supposes that subquarks perhaps do not obey Fermi statistics. Therefore we discuss other case for Montvay model and get six solutions under preserving asymptotic freedom condition. Four of them lead to SU(7) ×SU(7) grand unification at subquark level, but representions are different with Montvay model.
In the first part of this note, we have analysised phenomenologically the magnetic moment of W± bosons. After getting their bare μW and QW from electromagnetic vertex expressions, we have shown from effective Lagrangian that on what cases W± mesons would get anomalous magnetic moment and electric quadrupole moment. In the second part, we have discussed the processes γ+e-→W-+v by high energy electrons colliding with hard circular polarized photons, we have calculated the dσ/dt,σ(s) and the asymmetry coefficients A(s), these results show that one can determine the magnetic moment of W± mesons unambigously from measuring the energy dependence of these quantities.
We present first results on the properties of Chinese bismuth germanate for detection of photons. 12% light output relative to NaI(T1) with energy resolution AE/E=14%/√E(MeV) was measured for a 23×23×2mm3 crystal. The linearity between the light output and the energy of incoming photons is good. The fluorescence decay time is about 0.3μs at room temperature. Temperature effects were also studied.
We report on-line measurement of the proportional tube counter effeciency plateau. We measured the effeciency plateau of 6 proportional tube counters simultaneously with a TRS-80 micro-computer and CAMAC system.
A time-to-digital converter with the multiple hit capacity is described using a ECL random access memory (RAM) E859. It is able to process up to≤128 hits per signal wire for 8 wires of the drift chamber with full scale time range 2.56μs and time resolution 10ns, which corresponds to space resolution～210μm.
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