Sugie Shim

SYSTEMATIC DIRAC ANALYSES OF PROTON INELASTIC SCATTERINGS FROM AXIALLY SYMMETRIC DEFORMED NUCLEI

Relativistic Dirac coupled channel analyses using optical potential model are performed for the 800 MeV proton inelastic scatterings from 26Mg and the results are compared with those from several other axially symmetric deformed nuclei for the systematic Dirac analyses. Employing scalar-vector model, scalar and time-like vector optical potentials in Lorentz covariant form are calculated phenomenologically by solving Dirac coupled channel equations using sequential iteration method. Dirac equations are reduced to second-order differential equations to obtain Schrodinger equivalent effective central and spin-orbit optical potentials and it is found that the heavier deformed nucleus has the larger effective central potential strength. Using the first-order rotational collective model to describe the low-lying excited states of ground state rotational band in the deformed nuclei, deformation parameters for the excited states are calculated and it is observed that the lighter deformed nucleus has the larger deformation parameter for the lowest lying excited 2+ state at the 800 MeV proton inelastic scattering, indicating the stronger coupling to the ground state compared to that of heavier nucleus.

Dirac phenomenological analyses of unpolarized proton inelastic scattering from 22Ne

Unpolarized 800-MeV proton inelastic scatterings from an s-d shell nucleus 22Ne are analyzed by using phenomenological optical potentials in the Dirac coupled channel formalism. The first-order rotational collective model is used to obtain the transition optical potentials for the low-lying excited collective states that belong to the ground-state rotational band of the nucleus. The optical potential parameters of a Woods-Saxon shape and the deformation parameters of the excited states are varied phenomenologically by using the sequential iteration method to reproduce the experimental differential cross-section data. The effective central and spin-orbit optical potentials are obtained by reducing the Dirac equations to a Schrödinger-like second-order differential equations, and the surface-peaked phenomena are observed at the real effective central potentials when the scattering from 22Ne is considered. The obtained deformation parameters of the excited states are compared with those of the nonrelativistic calculations and with those for another s-d shell nucleus 20Ne. The deformation parameters for the 2+ and the 4+ states of the ground-state rotational band for the nucleus 22Ne are found to be smaller than those of 20Ne, indicating that the couplings of those states to the ground state are weaker for the 22Ne than for the 20Ne nucleus. The multistep channel coupling effect is confirmed to be important for the 4+ state excitation of the ground-state rotational band for proton inelastic scattering from the s-d shell nucleus 22Ne.

Identification of luminous region in porous silicon layers

Photoluminescence spectra were measured experimentally and compared with the results of the optical model calculations in oder to identify the region of photoluminescence in a porous silicon layer. It is found that the upper surface region in the porous silicon layer contributes most of the luminescence, by analyzing the interference patterns of the photoluminescence spectra and those of reflectances. It is confirmed by comparing the results of a detailed computer simulation with the experiments, and by analyzing the photoluminescence characteristics of a free-standing porous silicon film. Analyses of the photoluminescence spectra measured using several different excitation wavelengths also support our conclusion.

Dirac coupled channel analyses of proton inelastic scattering from the 40Ar nucleus

Inelastic scatterings of 0.8-GeV protons from 40Ar nuclei are analyzed by using an optical potential model in the Dirac coupled channel formalism. A rotational collective model is used to obtain the transition optical potentials for the low-lying excited states of the rotational band. The optical potential parameters of a Woods-Saxon shape and the deformation parameters of the excited states are searched phenomenologically by using the sequential iteration method to reproduce the experimental differential cross-section data. The effect of a multistep process is investigated by including the channel coupling between two excited states in addition to the couplings between the ground state and the excited states. The calculated deformation parameters of the excited states are compared with those obtained by using the nonrelativistic calculations. The results of the Dirac coupled channel calculations are found to show pretty good agreements with the experimental data for the ground state and the low-lying excited states. The multistep excitation process via channel coupling with the second 2+ state is found to be important for the excitation of the 4+ state for inelastic scatterings from deformed 40Ar nuclei.

Dirac coupled channel analyses of the 2− gamma vibrational band excitation in 20Ne

Dirac coupled channel analyses are performed using the optical potential model for the highlying excited states that belong to the 2− gamma vibrational band for 800 MeV unpolarized proton inelastic scatterings from 20Ne. First-order vibrational collective models are used to obtain the transition optical potentials to describe the high-lying excited vibrational collective states, and Lorentz-covariant scalar and time-like vector potentials are used as direct optical potentials. The complicated Dirac coupled channel equations are solved phenomenologically to reproduce the differential cross section data by varying the optical potential and the deformation parameters and by using the minimum chi-square method. Relativistic Dirac coupled channel calculation is able to describe the excited states of the 2− gamma vibrational band in 20Ne much better than the nonrelativistic coupled channel calculation, especially for the 2− and the 3− states of the band. The multistep excitation process via channel coupling with the 3− state is shown to be essential in describing the excitation of the 2− state, and the pure direct transition from the ground state is dominant for the excitation of the 3− state at the 2− gamma vibrational band in 20Ne.

Relativistic Dirac analyses of polarized proton scatterings to the 2+ gamma vibrational band in 24Mg and 26Mg

Relativistic Dirac analyses are performed phenomenologically for the high-lying excited states that belong to the 2+ gamma vibrational band at the 800 MeV polarized proton inelastic scatterings from the s-d shell nuclei, 24Mg and 26Mg. Optical potential model is used and scalar and time-like vector potentials are considered as direct potentials. First-order vibrational collective models are used to obtain the transition optical potentials to accommodate the high-lying excited vibrational collective states. The complicated Dirac coupled channel equations are solved phenomenologically to reproduce the differential cross section and analyzing power data by varying the optical potential and deformation parameters. It is found that the relativistic Dirac coupled channel calculation could describe the high-lying excited states of the 2+ gamma vibrational band at the 800 MeV polarized proton inelastic scatterings from s-d shell nuclei 24Mg and 26Mg reasonably well, showing mostly better agreement with the experi...

Dirac coupled-channel analyses of the high-lying excited states at 22Ne(p,p′)22Ne

Dirac phenomenological coupled-channel analyses are performed by using an optical potential model for the high-lying excited vibrational states at 800-MeV unpolarized proton inelastic scatterings from 22Ne nucleus. Lorentz-covariant scalar and time-like vector potentials are used as direct optical potentials, and the first-order vibrational collective model is used for the transition optical potentials to describe the high-lying excited vibrational collective states. The complicated Dirac coupled-channel equations are solved phenomenologically by using a sequential iteration method by varying the optical potential and the deformation parameters. Relativistic Dirac coupled-channel calculations are able to describe the high-lying excited states of the vibrational bands in 22Ne clearly better than the nonrelativistic coupled-channel calculations. The channel-coupling effects of the multistep process for the excited states of the vibrational bands are investigated. The deformation parameters obtained from the Dirac phenomenological calculations for the high-lying vibrational excited states in 22Ne are found to agree well with those obtained from the nonrelativistic calculations using the same Woods-Saxon potential shape.

A Modified Penna Model for Biological Aging

The Penna model for biological aging was modified. The reproducibility of each individual was determined according to the number of mutations relevant at that time. The results of Monte-Carlo calculations using the modified model show that the ranges of the reproducible age are broadened as time goes by, thus showing self-organization in biological aging to the direction of maximum self-conservation. In addition, the population, survival rate, and average life span were calculated and analyzed by changing the number of new mutations at birth. It is observed that the more the number of new mutations at birth is considered, the shorter the average life span that is obtained.