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A spectroscopy of a 10 Λ Be hypernucleus was carried out at JLab Hall C using the (e, e ′ K + ) reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of ∼ 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using p(e, e ′ K + )Λ,Σ 0 reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1 − and 2 − states) was obtained to be B Λ = 8.55 ± 0.07(stat.) ± 0.11(sys.) MeV. The result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on Charge Symmetry Breaking (CSB) effect in the ΛN interaction.

An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus,

Aerogel and waterČerenkov detectors were employed to tag kaons for a Λ hypernuclear spectroscopic experiment which used the (e, e ′ K + ) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ∼ 5 Gauss at the photomultiplier tubes ( PMT ) for these detectors which could not be easily shielded. As this field results in a lowered kaon detection efficiency, we implemented a bucking coil on each photomultiplier tubes to actively cancel this magnetic field, thus maximizing kaon detection efficiency.

The J-PARC E16 experiment will measure the invariant mass spectra of vector mesons in the e + e − decay channel in order to investigate the mass modification of hadrons in nuclear matter. This effect was reported by a predecessor experiment, KEK-PS E325, and we plan to measure the nuclear-size and meson-momentum dependence of the modification with higher statitstics, using a 30-GeV primary proton beam at the J-PARC high-momentum beam line. New detectors and readout circuits have been developed to cope with the high particle rate, namely, estimated as 5 kHz/mm 2 at most. The commissioning of the spectrometer and beam line is planned in FY2015.