Nuclear Structure Study

In order to understand the nuclear structure comprehensively, systematic spectroscopic data of nucleides, such as excitation energies, spins, parities, transition probabilities, and moments, are required. We are, therefore, investigating nuclear properties with the techniques of multiple Coulomb excitation, high-spin spectroscopy, and laser spectroscopy.

Themes

  • Multiple Coulomb Excitation Experiments
    As an accelerated nucleus collides with targets, the incident/target nucleus is excited in the repulsive Coulomb field, and then emit gamma-rays to de-excit. We measure the gamma-rays and the scattered particles with a multiple gamma-ray detector array, GEMINI-II, and particle detector array, LUNA. From the correlation between the gamma-yield and the particle scattered angle, we obtain Coulomb excitation porobability. Electromagnetic properties of low-lying nuclear structur such as B(E2)s, and Q moments can be deduced with the measured Coulomb excitaiton probabilities. Those propeerties are important to understand the character of low-lying nuclear structure.

  • High Spin Nuclear Spectroscopy
    High spin nuclear structures are studied. De-excitation gamma-rays from nuclei produced in a nuclear reaction between heavy nuclei and target nuclei are measured at the tandem-booster accelerator with the mcultiple gamma-ray detector array GEMINI-II.

  • Laser spectroscopy
    Laser spectroscopic techniques are applied to measure properties of unstable nuclei, such as nuclear spin, charge radius, and nuclear moments. Laser techniques that we are using and developing are, for example, laser induced fluorescence, laser ablation, laser photoionization, and Dynamic NucleAr Self-Polarization (DYNASP).

    Facilities

    Multiple Gamma-Ray Detector Array, GEMINI
    Multiple Gamma-Ray Detector Array, GEMINI-II, consisits of 16 Ge detectors coverd with BGO anti-Compton shields and 3 LOAX detectors.GEMNI was started with 12 Ge detectors and upgraded in 2002. Experiments on nuclear structure study of low-lying states and high-spin states are carried out.

    Multiple Gamma-ray Detector Array, "GEMINI-II" (since 2002)

     

         

    Multiple Gamma-ray Detector Array,"GEMINI"


    Position-Sensitive Particle Detector, LUNA

    We developed a position sensitive particle detector array that consists of position-sensitive photomultiplier tubes coverd with sheets of plastic scintilator. The advantages of the detactor are as follows: (1) applicable for high event rate (up to 105 cps), (2) good positional resolution: 0.5 - 1.0 mm, (3) high resistance to radiation damage, (4) compact (compared to gas counters), (5) easy to handle.

    Cluseter Computer System, HELIOS
    [] A Cluseter Computer System consisting of 70 PC/AT computers, which is used for data analys of experiments and theoritical calculation. (since 2001)