Katsuaki Sakamoto

PION CONDENSATION BASED ON A RELATIVISTIC DESCRIPTION OF PARTICLE-HOLE AND DELTA-HOLE EXCITATIONS

The critical density of neutral pion condensation is reinvestigated based on the relativistic framework and compared with nonrelativistic results. The particle-hole and delta-hole polarizations of the pion selfenergy are calculated in the relativistic way by using a new set of Landau–Migdal parameters derived from recent experimental data. It is concluded that the use of relativistic particle-hole and delta-hole excitations for the pion selfenergy increases the critical density, but still leads to condensation for densities from two to three times the normal nuclear matter density within the random phase approximation.

Temperature Coefficients Improvements of VHF Oscillator Circuit for OCXO

This paper presents the improvements of the temperature coefficient of the VHF oscillator circuit for OCXO. The solution for this discrepancy, not only to regulate the temperature precisely, but also the temperature coefficients of oscillator loop itself should be considered and reduced for better frequency-temperature performance to get higher frequency stability for the OCXO.

Development of ultra low noise VHF OCXO with excellent temperature stability

This paper presents development of ultra low noise VHF oven controlled crystal oscillator (OCXO) with excellent temperature stability. The OCXO had the low phase noise less than -170 dBc/Hz at 10 kHz Fourier frequency and the temperature stability within +/-20 ppb in the range of -20 to +70deg.C has been achieved.

VERTEX CORRECTIONS IN THE NUCLEAR SCHWINGER–DYSON FORMALISM

We develop the Nuclear Schwinger–Dyson (NSD) formalism to include the effects of ladder diagrams by modifying the vertex. In this extension, the NSD equation sums up both ring diagrams and ladder diagrams self-consistently. The results are compared with mean field theory, Hartree Fock and bare-vertex NSD calculations. It is shown that the vertex correction is important from the following viewpoints. First, the vertex correction greatly modifies the meson propagators, and we can avoid the ghost-pole from meson propagators in a self-consistent way. Secondly, it gives a large negative correlation-energy compared with the other calculations; as a result, it gives a softer equation of state which is preferable according to the experimental data.

Meson-Nucleon Vertex Corrections in the Cutoff Field Theory and Tensor Coupling

At zero-density, meson-nucleon vertex corrections are studied in the (F-W model with cutoff. It is shown that the properties of the vertex corrections are somewhat different from those described by the ordinary renormalization procedures when the cutoff is small « 5 GeV). The low-energy effective Lagrangian is constructed in the framework of the renormalization group method. Weak tensor and derivative couplings of meson-nucleon interactions may be needed in the low-energy effective theory of mesons and nucleons.

Vacuum Effects and Compressional Properties of Nuclear Matter in Cutoff Field Theory

Including the vacuum effects, the compressional properties of nuclear matter are studied in the cutoff field theory. Under the Hartree approximation, the low-energy effective Lagrangian is derived in the framework of the renormalization group methods. The coefficients are determined in a way where the physical results hardly depend on the value of the cutoff which is conveniently introduced into the theory. It is shown that, to reproduce the empirical data of the nucleus incompressibility, the compressibility of the nuclear matter is favorable to be 250

Active Antenna with Continuously Varying Frequency Performance

\sim

Antiproton Production in p + d Reaction at Subthreshold Energies

350MeV.

Active microstrip planar antenna for frequency switching

A noble microstrip patch antenna with the capability to control the operating frequency continuously is proposed that is an example of the basic research on “Reconfigurable” microwave circuits. The antenna is composed of a planar patch and variable capacitors integrated on the patch conductor. The bias voltage fed to the variable capacitors to control the surface current on the patch can continuously control the operating frequency. The basic performance of the antenna has been successfully verified by both FDTD analysis and a primary experiment.

Harmonic oscillator using transmission line resonator

An enhancement of antiprotons produced in the p + d reaction in comparison over those produced in the p + p elementary reaction is investigated. In the neighborhood of the subthreshold energy, the enhancement is caused by the difference in threshold energies for antiproton production. The cross section of the p + d reaction, on the other hand, becomes just twice that in the elementary p + p reaction at the incident energy far from the threshold energy when non-nucleon components in the deuteron target are not considered.An enhancement of antiprotons produced in p+d reaction in comparison with ones in p+p elementary reaction is investigated. In the neighborhood of subthreshold energy the enhancement is caused by the difference of available energies for antiproton production. The cross section in p+d reaction, on the other hand, becomes just twice of the one in elementary p+p reaction at the incident energy far from the threshold energy when non-nucleonic components in deuteron target are not considered.