1989 Vol. 13, No. 5
Display Method: |
When hard X-ray is detected by a multiwire proportional chamber filled with Xe or Kr,the intrinsic K-fluorescent photon,which of ten escapes from the original cell and is absorbed in other cell of the chamber,provides an accomtanied signal with certain amplitude.A processing technique of such signal,called escape gating technique,can improve both the energy resolution and background rejection efficiency of the detector.In this paper,we describe this technique and its application in our balloon borne hard X-ray spectroscope successfully launched on 31 August,1987,at an altitude of 37 km above sea level near Beijing.
We consider in detail the complementarity principle between the Higgs Phase and the confining phase in SU(N) unified preon models.We analyse all anormaly-free and asymptotically free representations of all SU(N) groups,and we get the simplest representation of SU(N) modls and the generations of quarks and leptons gN≥4.
By making use of the High-order Adiabatio Approximation Method proposed by the author,the problems of Solarneutrino oscillations are studied and high-order approximate solutions for the oscillation equations are obtained.For the cases with two and three generations,we find out non-adiabatic corrections to the probability of neutrino transition and also discuss the relations of CP-violation,Berry's phases and neutrino oscillations.
A quantization scheme for boson string with Weyl ordering is proposed in this paper.Inconsistency between Hermiticity requirement in coordinate space and normal ordering in oscillator space is avoided.The Virasoro algebra of Nambu-Goto string with Weyl ordering were derived by virtue of principal value sum where all central terms vanished.We also calculated the angular momentum operators of the string and their commutation rules,and reached the conclusion that dimension of the string is 26(D=26).
The geometric quantization for bosonic strings is discussed in this paper.Relations among different polarizations and representations of operators in different polarizations are given.It is pointed out that the prequantization Hilbert space is the unitary representation of the conformal group where the centre term of Virasoro algebra does not exist but this representation is reducible.By polarization it is reduced into two projective representations with the phase factors with opposite signs.Then the conformal anomaly is obtained.In the viewpoint of geometric quantization,the emergence of the conformal anomaly stems from the fact that polarization is introduced because the quantum states of string must satisfy the uncertainty relation but all generators of conformal transformation don't preserve the same polarization.
The influence of the effective mass of gluon on heavy quark potential is discussed in the framework of ellipsoidal bag model.The heavy potentials are calculated at the effective mass of gluon M=0,0.2,0.4,0.6,and 1.0GeV respectively.The results show that the potentials (excluding Yakawa potential) are approximately linear,the slopes decrease with the increasing of the effective mass of gluon.
In the framework of the distorted wave impulse approximation,we discuss the antiproton nucleus inelastic scattering.Calculations are preuented for the 12C(p,p)12C, 2+ and 3+ states at antiproton energies of 46.8 and 179.7MeV.Distorted waves are calculated by exact partial wave calculation.It is shown that the DWIA is quite good for the low energies.The importance of the behaviour of bound state wave function is discussed.Due to the strong absorption of antiproton by nucleus,the use of exact bound state wave function is essential.
A CsI(Tl) scintillator,with two different light decay components,is used to detect and identify light particles p,d,α and Li with a low energy threshold.The addition of a Si semiconductor in front of the CsI(Tl) scintillator allows the identification of light particles.
In order to study the transport of beams with arbitary phase space contours,the spline function representation of phase space contours is proposed in this paper.Having fitted the phase space contours with spline functions,phase space transformations are reduced to spline function transformations,and the envelopes of beams can bt expressed by spline functions.Some typical examples are presented to illustrate the usefulness of this method.
The fission probability and the mean square deviation of position as a function of time are calculated by solving the Langevin equation directly with a computer generated randon force. The fesults are compared with the results by Weidenmuller et al.which are obtained by solving the Fokker-Plank equation numerically.The method may be easy to easy to extend to multiple dimension cases.
The dynamics of fission are calculated by the description of Cassinian ovaloid with one body dissipation by deducing factor 0.2.The ring of center of mass is introduced instead of the center of mass.The function of one body dissipation vs deformation parameter has been obtained.Taken A=238 as an example,the relation between time from saddle to scission and excitation energy at saddle are calculated.
A unified parametrized formula of total reaction cross section σR from low energy to intermediate and high energy has been proposed.Most of the experiment results in whole energy range can be reproduced by this parametrization.The relation of σR with neutron excess degree of freedom (N-Z) and the relation of interaction radius R with incident energy Ecm-1/3 have also been discussed.
This paper investigates the non-statistical effects in 27Al(n,γ) and 28Si(n,γ) reactions.The neutron energies studied range from thermal to 2MeV.The calculated results show that in comparison with medium and heavy nuclei the fractions of non-statistical effects in the total (n,γ) cross sections in the two nuclides are extremely strong.The physical significance of the results and its implication with the measured correlation coefficients are discussed.
Based on the participant-spectator picture,the distributions of the zero-degree energy and the transverse energy,and the jojnt distribution of the mentioned two energies in relativistic heavy ion collisions are calculated.For 60A GeV and 200A GeV 16O colliding with different targets our results fit the new data of WA80 at CERN very well.
The azimuthal anisotropy of gamma-family events obtained by mountain emulsion chambers is studied.Adopted D-ND and SD-SH models.gamma-family phenomena are simulated and the simulation reproduces anisotro pical events with adequate frequency.The study indicates that the few-particle diffractive production in fragmentation region mainly accounts for the azimuthal anisotropical events.QCD-jet production is shown not to be the main reason of these evets.
- A SCOAP3 participating journal - free Open Access publication for qualifying articles
- Average 24 days to first decision
- Fast-track publication for selected articles
- Subscriptions at over 3000 institutions worldwide
- Free English editing on all accepted articles
- The 2019 National Day closure
- Editor Recruitment
- CPC authorship won the âIOP Publishing awards top cited Chinese authorsâ
- The 2019 summer holiday-Office closure
- 2018 Impact Factor 5.861