Spectroscopy of a BeΛ10 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,Σ0 reactions allowed us to determine the energy levels; and the binding energy of the ground-state peak (mixture of 1- and 2- states) was found to be BΛ=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 the charge symmetry breaking effect in the ΛN interaction.
Bibliographical noteFunding Information:
The program at JLab Hall-C is supported by JSPS KAKENHI Grants No. 12002001, No. 15684005, No. 16GS0201, and No. 244123 (Grant-in-Aid for JSPS fellow), JSPS Core-to-Core Program No. 21002, and JSPS Strategic Young Researcher Overseas Visits Program for Accelerating Brain Circulation No. R2201. This work is supported by U.S. Department of Energy Contracts No. DE-AC05-84ER40150, No. DE-AC05-06OR23177, No. DE-FG02-99ER41065, No. DE-FG02-97ER41047, No. DE-AC02-06CH11357, No. DE-FG02-00ER41110, and No. DE-AC02-98CH10886, and US-NSF Contracts No. 013815 and No. 0758095.