High-accuracy B_Λ measurement of light hypernuclei in nuclear emulsion (1)

Measurement of charge symmetry breaking effect in hypernuclei is an important probe for the strangeness physics. Nuclear emulsion has an essential role to determine Λ binding energy (B_Λ) of light hypernuclei, because we can measure the B_Λ which have various mass numbers, atomic numbers and decay modes in the same emulsion plate. 

In recent years, measurements by counters have been advanced. The energy-level spacing and the ground state binding energy were obtained, but the differences from the past emulsion studies are left. A large error of B_Λ of hypernuclei with A≥9 is due to less event number.

We are performing the latest emulsion experiment, J-PARC E07. A huge number of light single hypernuclei, which is mainly produced by kaon-nucleus direct process, will be extracted from the “overall” analysis. A current analysis of small parts predicts that the ~10⁶ of hypernuclei mesonic-like events are recorded, which is one order of higher than the past experiments. The high-accuracy B_Λ measurement will be achieved with the new events.

We will report the results of single hypernuclei candidates found in E07 emulsion plates and discuss the systematic error of the measurement with the advanced energy calibration method.