1988 Vol. 12, No. 3
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A positron CT camera system using multiwire proportional chambers as detectors is reported.This system is composed of two high density MWPC γ-ray detectors,an electronic readout system and a computer for data processing.The tomography of three dimensions is obtained.The imaging matrix 64×64×16.
A non-focusing magnetic spectrometer design for electron scattering in medium energy region is proposed.The positions read out from the position-sensitive detectors in the spectrometer are used for track reconstruction and momentum measurement by means of a computer program.The construction of this spectromenter is rather simple and there is no special technique and element for correction to aberration.It is suitable for usage of spectrometer with large solid angle and wide momentum range.The momentum resolution,momentum range and acceptance in our case are calculated by Monte Carlo simulation.
The pion fragmentational function is calculated.In high energy region,the asymptotic freedom perturbation theory is used.After passing through a certain distance the quarks break into hadrons because of confinement,which plays a role in the low energy region and pions must be considered as Goldstone boson and must be a result of dynamical breaking.In this article the fragmenta tional function in the low energy region is calculated with dynamical breaking mechanism.The result obtained for the fragmentational function is in agreement with experiments.
The BRS charge QB of BRSSS Spinning String model in Md×G space-time is explicitly given.By means of the nilpotency of the BRS charge,the critical dimension and parameters αR and αNS could be fixed;and with the help of the BRS charge a BRS invariant free open BRSSS string field theory could be established.In this model,we find that supersymmetry and BRS invariance could be compatible only when the group G is abelian.And finally,the massless sector comprising gauge fields with indices of group G is demonstrated.
We constructed an SU(9) grand unified preon model which satisfies the complementarity principle between Higgs phase and confining phase.The model ends up with the prediction of four generations of quarks and leptons,and an appropriate hypercolor scale.
The fundamental U(1)-lattice-gauge-Higgs system with radial degrees of freedom in d=4 is studied by using variational-cumulant expansion method.Equations for determining the first-order phase transitions of the model is given.Our result is qualitatively in agreement with MC result.The result for d=5 is also given.
Using the empirical formula on FN(Fe)/FN(D) found by us and generalizing the method used by CERN UA1 Collaboration in analysing the process p+Fe→2jet+X,a simple method to calculate p+Fe→2jet+X process is presented.Our results are compared with experimental data and other theoretical results.Some results are to be checked by future experiments.
A specialkind of soliton solution in the skyrme model with the haryon number B=2 is investigated and quantized.The resultant mass spectrum is found to possess some peculiar properties but still in agreement with experiments.Our further studies show that it is impossible to construct the above mentioned soliton solution in the case with B=1,3,5,…,while on the other hand there exsists such soliton solution in the case with B=0,4,…,as well,which also leads to the afore mentioned peculiar properties.Finally,it is worthwhile to note that the B=0 soliton is just the famous "Hopf soliton".
By using group representation theory,the quasi-adiabatic approximation solution of the schrodinger equation of a quantum system with slowly-changing Hamiltonian are presented in this paper.We not only obtained the Berry phase factor and strictly proved the quantum adiabatic theorem as the zeroth-order approximation,but also studied the universal Berry phase factor and its geometrical interpretation when the adiabatic condition is violated.It is pointed out that this universal Berry phase factor has observable effects.
The similarity of the charge form factors observed experimentally between 3He and 3H and the central hole of 3He charge density are in conflict with traditional nuclear structure theory.We claim that these conflicrs are strong singnals for the existence of multiple quark clusters in nuclei.Hybrid Quark Hadron Model successfully explain the experimental phenomena.
In this paper,some methods of producing local skew quadrupole field in accelerator ring are studied.It can be used to find the suitable positions and strength of skew quadrupole field to remove the coupling between horizontal and vertical oscillations of beam,Taking BEPC as an example,some calculated results are given.
The beam test of the 250MeV section of BEPC 1.1/1.4GeV e± LINAC was performed four times during its installation phase.In May of 1987,electron beam of 760mA and 250MeV was obtained and positron beam current of 2.5mA and 99MeV was observed when an electron beam of 785MeV bombarding a tungsten target.The main parameters of LINAC met the design values and achieved the same technical level of similar accelerators in other countries.
Complete fusion cross sections have been measured for 12C+159Tb and 12C+165Ho reactions by using K-X rays of evaporation residues with Si(Li)spectrometer.The half-lives of evaporation residues and its yield distributions as a function of incident energy have also been obtained.The experimental values for the complete fusion cross section were compared with the theoretical ones.
Angular distributions of fission fragments were measured for a series of compound nuclei formed in the bombardment of 169Tm,175Lu,181Ta,W,Re,Pt,197Au,Pb and 209Bi by 12C ions with mica track detectors and gold surface barrier silicon detectors.All the measured angular distributions can be fitted satisfactorily by the theoretical formula based on saddle point model.The variation trend for K2 with the excitation energy increasing was given at various ranges of the fission parameter Z2/A.
A simple approach of Coulomb correction to the p-4He low energy scattering phase shifts is proposed,in which the channel radius of each partial wave is taken as an adjustable parameter.By using the Coulomb correction the n-4He scattering observables predicted from p-4He scattering phase shifts are in excllent agreement with experiment.Our calculations show that the neutron polarization depends sensitively on the channel radius of p waves and the obtained channel radius are adeguate to the different sets of phase shifts.
ACQM is applied to study the μ－-mesenic molecules (αp,μ－) and (αp,2μ－).It is found that the ground state X2Σ+ of (αp,2μ－) is the repulsive one and the ground state X1Σ+ of (αp,2μ－) is a bound state with the equilibrium proton-proton separation Re=0.0078bohr and the minimum energy E=－551.78a.u..
Based on the recommended level density formula of the Fermi gas model and considering the modifications at low excitation energy,a synthesis level density formula is proposed.From the mean neutron resonance spacing Dexp for 248 nuclei and the cumulative numbers of levels for 529 nuclei,a set of parameters is determined.
SO(Bvπ)(6) limit of U(B)(6)×U(v)(12)×U(π)(4) dynamical symmetry in odd-odd nuclei is discussed Energy formula and wave functions are obtained,and exaetd expressions for E2 trasition rates and and one-nucleon transfer intensities are derived.The spectra of 198Au119 and 188Ir111 are compared with the exprimental values.
The E2 reduced transition probabilities between the d-a cluster states of 6Li were calculated by the RGM in this paper.The resulting B(E2;E1→E0)=21.06fm4 consistented with the experimental value 25.1±2.0fm4 more than the calculated values of the double-well cluster model including p-state exciting and LCCO.Also,the B(E2;E3→E0)=9.67fm4 coincided with the exprimental value 6.483±3.360fm4 within the error range.
We present a variational calculation of C=+1 and C=－1 glueball masses in 2+1 dimensional SU(3) lattice gauge theory using a Hamiltonian in which the ground state is exactly known.In the range 0<1/g2≤6,we obtain good scaling behaviour am+=36.1g2 and am－=5.98g2.
The effect of the interference of odd and even waves on the spatial correlation of a pair of valent nucleons has been investigated.
The assumption of indistinguishability of quarks in the region of overlapping of nucleon wave functions leads to the model of joint possessing of quarks between nucleous.Besides the examination by the data of A-dependent EMC effect,the model gives the increments of average nucleon radii in various nuclei;the percentage ratios of 6-quark cluster in various nuclei,and explains the formation and dissociation of multi-quark clusters.A new possible type of fluidity of quark——"conductivity" in nuclei s predicted by the model.
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