1988 Vol. 12, No. S3
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A non-focusing magnetic spectrometer designed 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 through a computer program. The structure of this spectrometer is rather simple and no special technique and element are required for the correction to aberration. It is suitable for the usage of a spectrometer with a large solid angle and wide momentum range. The momentum resolution, momentum range, and acceptance in our case are calculated by Monte Cario simulation.
Some problems related to the beam dynamics computation of the transverse motion for the 35 MeV Beijing Proton Linac are discussed. The suitability and reliability of the computations are proved. These computations are useful for guiding the beam testing of the linac.
The Higgs-U(1) gauge system (Q = 1) with radial degrees of freedom in d = 4 is studied by using variational-cumulant expansion method Equations for determining the phase transitions of the model are given. Our result is qualitatively in agreement with Monte Carlo result in the case of d = 4. The result of d = 5 is also given.
Using the empirical formula of F2N(Fe)/F2N(D) found by us and generalizing the methcxi used by CERN, UA1 Collaboration in analyzing the process p + p→2jet + X, a simple calculating method on p + Fe→2jet + X process is presented. Our results are compared with the experimental data and the other theoretical calculations. Some results will be checked by future experiments.
By analyzing the symmetry of a quantum system in terms of the method of the group theory, a quasi-adiabatic approximate method for solving a Schrodinger equation is presented. The method is to study the transition problem of the quantum system with the Hamiltonian that changes slowly but finitely. As a result of zeroth-order approximate, the quantum adiabatic theorem for the degenerate case is proved strictly, and the topological Berry's phase factors are introduced. A geometrical interpretation of the violation in the adiabatic condition is given, and it is demonstrated that the Berry^ phase factors exist generally in the quantum processes with the time scale which is comparable with the pericxJ of the Hamiltonian. Finally, a possible observable effect is pointed out of the Berry's phase factor in a slowly changing process where the adiabatic condition is violated.
The differential cross sections of the antiproton elastic scattering on the 12C, 16,18O, 40Ca and 208Pb at the energies of 50 MeV and 180 MeV are calculated and analyzed by the optical potential model. It shows that the antiproton optical potential has a strong absorption property. In making optical potential best fit to the experimental data, it is found that the diffuseness parameters can vary only in a narrow region and increase with heavier nuclei. The real part of the optical potential is very shallow. The absorption coefficients approach to zero inside the target nucleus. Thus, the elastic scattering takes place at the surface region of a nucleus.
In the framework of the fixed-scattering field theory, we construct microscopically a second-order pion-nucleus Iso-elastic optical potential by including two-nucleon correlations. The double charge exchange reactions to the double isobaric analog states are calculated by using our theoretical optical potential. For the incident pion energies ranging from 0 to 300 MeV, the S and P partial waves are included in the πN amplitude.
The relativistic microscopic optical potential (RMOP) of a nucleon above the Fermi sea based on the Walecka's model is used to systematically analyze the proton elastic scattering from nuclei for a variety of energies. It turns out that the experimental data of the differential cross sections, the analyzing powers and the spin rotation functions are reproduced satisfactorily except for large angles. This simple model might be used in the nuclear transport theory and heavy ion collision and to take account of both the nuclear medium and relativistic effects.
The large-angle elastic cross sections for the scatterings of the π+ and π- from 16O at 114 MeVare calculated using the first-order optical potential constructed from the α-particle model of 16O. The calculated results show that obvious improvement is obtained on the calculations employing the first-order optical potential of the Kisslinger type.
Through a covariant regularization of the chiral fermion current, we derive the covariant fermion current divergence anomaly as well as the covariant Gauss law commutator anomaly of the chiral gauge theory in the canonical formalism.
Complete fusion cross sections are measured for 12C + 159Tb and 12C + 165Ho reactions by measuring K-X rays of the evaporation residues with Si(Li) spectrometer. The half-lives of the evaporation residues and their yield distributions as a function of the incident energy are also obtained. The experimental values for the complete fusion cross sections are compared with the theoretical ones.
The particle-number-conserving approach for treating nuclear pairing correlation is extended to treat the eigenvalue problem of the cranking Hamiltonian. Detailed information on the seniority structure and the K-structure of the low-lying bands, and their spin alignments, signature splittings, and pair-transfer matrix elements can be provided in this formalism.
A simple approach of the 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 observable predicted from p-4He scattering phase shifts are in excellent agreement with the experiment. Our calculations show that the neutron polarization depends sensitively on the channel radii of P waves and the obtained channel radii are adequate to all different sets of phase shifts.
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