1988 Vol. 12, No. 1
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Practical formulas for calculating position sensing by charge division were given.They were applied to experiments on self-quenching streamer (SQS) tubes with different shorter wire lengths (smallest resistance 425Ω) and the position resolution obtained was 1.1% for a 37.3cm wire.The error of position sensing by charge division on single tube was compared to that on parallelly connected double tuble tubes.Possible errors of determing position of the shower "Axis" by charge division method on the wires were studied.
The numerical calculation were used to correct the measured K X-ray intensities in thick target PIXE analyses for the following matrix effects: slowing down of protons,absorption of characteristic X-ray,and X-ray induced X-ray emission in the sample.The efficiency calibrations for PIXE analysis system were made by means of the Monte Carlo technique.Based on these corrections and calibrations,the PIXE analysis results on some thick speciments made by ourself were obtained without the use of standard and they showed a good agreement between the measured and the known values of contents.
In this paper the construction and performance of an intelligent environmental neutron and gamma monitoring system are described.
The neutron monitor has high sensitivity,light weight and small size.A charge pump circuit is adopted for I-F converter of the gamma monitor.Local data acquisitor consists of CMOS single piece processor with high speed and low power dissipation.A FLEX microcomputer is used as remote centre computer for data handling and graph plotting.The system has been operating contionuously for more one year with high stability and reliability.
By solving the constraint equations of two-loop finiteness another type of two-loop finite SU(5) ground unified model is given in this paper.There is only one pair of light Higgs doublet,and the other Higgs particles are all superheavy (～Mx).The ordinary CKM-mixing can be obtained only in the low energy region.
The Monte Carlo renormalization group method proposed by Callaway is applied to φ4 model on two dimensional triangle lattice.The flow diagram,fixed point and critical exponent are determined,There is no fixed point in the range of 0.1<λ<109.The large λ limit,as expected,is consistent with the Ising model.
Because the de Rham complex on compact manifolds with boundary must satify the elliptic boundary conditions,their boundary metric must be a product if the structures of supersymmetry satifying the conditions exist in the field manifolds with boundary on 0+1 dimensions.Using the witten index for a supersymmetric field theory,we proved the Gauss-Bonnet-Chern theorem.
In the SU(2)×SU(2) Skyrme model,one can treat the topological soliton-Skyrmion having baryon number B=1 as baryon.In this paper,we have used Skyrmion and anti-Skyrmion to construct a kind of composite soliton solution having baryon number B=0 but Hopf index H=1 and have found its mass depends on a dimensionless parameter p(0<p≤1).In addition,we have also discussed the quantization of the soliton and the probability of treating the quantized soliton as baryonium.
The Hamiltonian of a radial equation is defined on a half-line,and there is a close relation between its hermitian and the boundary condition of the wave functions at the origin.If the wave functions are nonvanishing and convergent at the origin,the Hamiltonian has a one-parameter family of self-adjoint extensions which are related with the vanishness of the radial probability current at the origin.In this paper the problem on the hermitian of the Hamiltonian of a radial equation is studied systematically.Some methods for determining the parameter for the fermion moving in the magnetic monopole field are discussed.
The contributions of tadpole diagrams including t and c quark intermediate states to the amplitude of K0→2π and ε′/ε are analysed.The result shows it is quite possible that their contributions are the most important ones.They may give enough ΔI=1/2 enhancement for a reasonable quark relative momentum cutoff value which depends on K0 wave function.However,the calcualation value of │ε′/ε│ is too large if we suppose all CP violation effects come from the,Kobayashi-Maskawa phase δ. Perhaps,One approach to solve this difficulty is to assume the ε comes mainly from superweak CP violation.
Assuming a nucleon as a thermodynamical system composed of partons (quarks and glue),we have disoussed its temperation T and chemical potential μ and nave derived relations between the x distribution functions of partons in the nucleon and its correspond statistical distribution functions.Through comparing glue of the nucleon with photons of the black-body,we have got effective temperature of the nucleon.By assuming μ of u,d quark to be the same and choosing their reasonable values,and after using the rescaling scheme to determine T of the mucleon,the statistical model could explain the EMC effect very well.If the gluon's chemical potential has a small and negative quantity,the statistical model could also fit the ratio Rg in μ+N→J/ψ+X process quite well and could explain why it seems "too large" in the small x region.
In the frame of DWBA and by including multinucleon effects in the optical potential and transition matrix elements,we calculate 13C(π+,π0)19N(IAS) reactions.Angular distribution at 165MeV,forward angle excitation function and integrated cross sections for this reactions are studied.A formula for mass dependence of forward differential cross sections is derived.
We analyse the multiplicity distributions of negative particles produced in α-α collisions at SNN=31.2GeV by using a Glauber-type multiple collision model in which the projectile nucleons degrade in energy as they make collisions with target nucleons.The energy loss suffered by the projectile nucleons in the passage through the target nucleus is explicitly considered in the calculation.The agreement with experiments is good.
The charge dispersion of fragments in high energy p+Cu,Kr and Xe reactions are calculated by statistical model and Monte Carlo technique.The corresponding data are reproduced quite well.It is shown that the charge dispersions are all nearly gaussian.The mass dependence of the most probable fragment charge reflects the rest target memory effect.
The finite element method developed recent years and used for solving two-dimensional timedependent magnetic fields is introduced.Using this method,we have calculated the eddycurrent fields of a C-type solid yoke bending magnet which is a model magnet of the 800MeV electron storage ring in Hefei.The calculation results are in agreement with measurements.The possibility of applying a solid yoke bending magnet in the case of slow acceleration is discussed.
The construction,operation principle and performance of a parallel plate avalanche counter with an active area of 60×400mm2 and another one with an active area of 70×140mm2 and one dimensional position sensitivity are described in detail.It is discussed how to combine a large solid angle time-of-flight setup by using the two counters described above.
Neutron capture cross sections of W and Gd were measured relative to that of Au at six neutron energy values by using a large liquid scintillator tank and time-of-flight technique.The accelerator used was a 2.5MV pulsed van de Graff.The present results agree well with other recent measurement.
The intrinsic structure of the eigenfunctions of Cranking Shell Model hamiltonian and the pairing phase transition at high rotational frequency are investigated with the particle-number-conserving approach.Pair-transfer matrix elements and the K-structure of the wave functions display similar behaviour under the Coriolis interaction and hence both of them may be used to indicate the pairing phase transition.The blocking effects on pairing parameter,,are much more important than the Coriolis anti-pairing effects.
The dynamics of the dissipation collision for light system are calculated by using the motion equations including six degrees of freedom.The angular distribution and the interaction time,the energy dissipation and the deformation of the fragment etc are discussed.
Master equation is solved numerically for mass drift and fluctuation of three reactions.The driven potential is calculated by means of D.Myers' mass formula plus shell correction.The results indicated that the lack of mass drift in the range of zero to a considerable energy loss in heavy ion collisions could be explained by transport theory.Due to small mass mobility coefficient the mass does not drift considerably during a short time interval.The effect of shell structure in the driven potential is obvious for mass relaxation in low energy loss region.
The α-correlation in a single-level model with pairing forces independent of spin and isospin was discussed.With the help of the Boson-Fermion representation,analytical solutions to this problem were obtained,analytical expressions for the α-correlation energy and reduced rate of α-transfer were given,and the significance of the obtained results were discussed.
Some isoscalar factors for the group chain SO(6) SO(5) are calculated by using the method of reduced matrix elements and the building-up principle.
πh9/2 alignment in Pt even isotopes has calculated and discussed systematically.It is found that Δhωc≡hωc(πh9/2)－hωc(νi13/2) approches the minimum,about 75keV.for 78184Pt106 by using modified Nilsson's parameters κμ.This result is in agreement with the experimental evidence that the big up-bend observed in the yeast band of 184Pt is caused by the lose alignment of πh9/2 and νi13/2.While the standard Nilsson's κμ can not give out such a result.The problem of the orderof πh9/2 and νi13/2 alignments needs further investigation.The pretical prediction about the πh9/2 alignment frequency for neighboring Pt even isotopes should be checked by new experiments.
A variational calculation of the mass gap in 2+1 dimensional SU(2) lattice gauge theory by using a Hamiltonian with the ground state being exactly known is made.In the range 0≤1/g2≤7,a good scaling behaviour am=2.28g2 is obtained,which is in agreement with weak-coupling perturbation theory.
Decay rates of ρ-meson into two π mesons and K* into Kπ mesons are calculated by using the One-Gluon-Exchange Quark-Antiquark pair creation model.The results are in agreement with the experimental data.
By means of the imaginary time Greer's function method,we extend the One Pion Exchange Potential (OPEP) of nucleon-nucleon interaction to finite temperature.We sum up all the bubble diagrams and find that the temperature effect to OPEP is small at low temperature region but large at high temperature region.The effective mass of pion field Mπ(β) will become imaginary at critical temperature Tc=177MeV.It means that the attractive OPEP will disappear at Tc and the phase transition happens.
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