Intermediate Energy Nuclear Physics group studies atomic nuclei by use of electron and photon beams. Electrons and photons are clean tools to study nuclear structure, since the interaction is weak, and is well understood by the established quantum electro dynamics. Our interests extend over many aspects in nuclear physics. In order to study them, we also use hadron probes in a wide energy range.
Collectivity of Nuclei
When a nucleus is irradiated by a few tens MeV photons whose wavelength is comparable to the nuclear size, a collective motion, for example, the giant resonance, is excited. The characteristics of the resonance, such as peak energies, widths and decay modes, are rich source to investigate the nuclear structure. We study the giant resonance by detecting decayed particles, such as photons, protons and neutrons, with modern technique.
Mesons and Nucleons in Nuclei
We can investigate nucleons inside the nucleus by using high-energy photons whose wavelengths are smaller than the nuclear size. By detecting several nucleons in coincidence, we can probe how they are interacting in the nucleus. In a photon energy of a few hundreds MeV, various mesons are also photo-produced in the nucleus. We can study the meson-nucleus interaction, and various nucleon resonances, since mesons strongly couple to the nucleon resonance.
Quark Nuclear Physics
A further step using much higher energy photons, whose wavelength is short enough to probe inside the nucleon, might be taken to investigate the nucleon structure. Bremsstrahrung γ beam with high duty factor (up to 70%) is now used for the photoproduction of K0 and π mesons on nucleon. We have been developing the liquid deuterium cryostat for a neutron target. The exciting researches are planned to be carried out using completely polarized GeV photon beams.
The hyperon-nucleon scattering is studied for understanding of the interaction between hyperon and nucleon. The scintillating fiber active target with IIT readout was developed. It works both as the target for hyperon production through (π±,K+) reaction and as the proton target for elastic scattering of hyperons. The momentum region for Σ± and Λ is from 300 MeV/c to 1000 MeV/c. The results concerning the cross sections for Σ±-p elastic scattering were obtained and compared to the theoretical predictions from several model calculations.