| 研究実績の概要 |
Key tests of nuclear physics are found at the limits of nuclear existence, where
nuclei are unbound with respect to nucleon emission. The two-neutron decay of the weakly unbound nucleus 26O (Oxygen 26) is a unique probe of the long-predicted existence of a spatially localized two-neutron correlation, dineutron. We plan to measure the angular correlation of the emitted two neutrons from 26O, in order to obtain the direct evidence of the dineutron for the first time. For this purpose, we are now developing the high-resolution neutron detector array, HIME.
In FY2018, we have nearly completed the construction of HIME. Also, we made a test experiment using the cosmic ray as well as the neutron beam at 200 MeV at RCNP, Osaka University. In such measurements, we could confirm the basic performance of HIME, in particular on the timing reasolution.
In parallel, in order to investigate the dineutron correlation for other cases, we made some progress in the data analysis for the Coulomb breakup measurement for the two-neutron halo nucleus 19B (boron 19) at 240 MeV/nucleon. The basic calibrations, for the detectors (drift chambers, hodoscope, neutron detectors), were done, and the resonance spectrum for the 17B+n system was extracted.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The analysis of the Coulomb breakup of 19B has made a progress, where all the calibrations for charged particle detectors and the neutron detectors were done. With that we are very close to the final spectrum for the electric dipole response, which is crucial to discuss its dineutron structure. For the development of HIME, we could nearly complete the construction, and make a performance test using the cosmic ray as well as the neutron beam.
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| 今後の研究の推進方策 |
We proceed the data analysis of the Coulomb breakup of 19B. We extract the 2n+17B relative energy spectrum, which is then used to extract the electric dipole strength distribution. This distribution is relevant to the dineutron correlation in 19B.
For HIME, we will introduce the new integrated electronics from the collaborators in Germany (TU Darmstadt/GSI). This test is planned in May, this year. After that, we complete all the HIME construction. Then we are ready to run the beam time for 26O. For 26O, we need 48Ca beam from RIKEN, RIBF. We also consider the other experiment using 13Li, 6He for their dineutrons, if RIKEN cannot provide 48Ca primary beam.
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