Study of -N interaction by measurement of twin hypernuclei with hybrid emulsion method at J-PARC
Hayakawa, Shuhei; Yoshida, Junya
The studies of hyperon-nucleon and hyperon-hyperon interactions are necessary for the understanding of general baryon-baryon interaction. Even in the = -1 sector such as and , the available data is limited. As for the = -2 sector such as and , there are few experimental data. The J-PARC E07 experiment was performed to investigate = -2 hypernuclei at J-PARC K1.8 beam line. Using a K- meson beam with the momentum of 1.81 GeV/c, - hyperons are produced in the quasi-free , K- reaction at a diamond target. A method using combined information between two spectrometers and nuclear emulsion, called hybrid emulsion method, was conducted by using silicon-strip detectors and one hundred eighteen emulsion modules. A twin hypernuclear event, named IBUKI event, was observed with a newly developed scanning system. At the - capture point, two hypernuclei of Be and He were the most likely to be produced by the conservation laws of energy and momentum. The reaction process of the IBUKI event was identified as - + N Be + He. The binding energy of - + N system was determined to be 1.27 0.21 MeV. From the consideration of an excited state, the energy level for Be was interpreted to be the ground state (2-) or the other state of the spin doublet (1-). The IBUKI event was the first event whose binding energy was determined with a little ambiguity. The binding energy indicates a bound state of the -N system by an attractive interaction. In this talk, we would like to report the above result of the IBUKI event.