Experimental study of Xi hypernuclei

Double hypernuclei (S=-2 nuclei) as double-Lam and Xi hypernuclei were studied with nuclear emulsion. Regarding double-Lam hypernucleus, the NAGARA event has been set as a ruler for the discussion of the Lam-Lam interaction. The KISO event showed the presence of deeply bound state of Xi- inside nucleus.

In the E373 experiment at KEK-PS, we have located ~430 Xi- stop events with evaporation track(s) with the recent analysis. Among them, several events were detected as two single-Lam hypernuclei emission at Xi- capture point in the emulsion. With the recent development of particle-charge-detection method, one event was uniquely identified for its nuclide and shows a deeper state than the KISO event case. Its bound seems the several MeV level, preliminary. This event was reported to has large errors for the binding energy due to ambiguity for the Xi- capture point at the JPS Autumn Meeting in 2017. We have developed a method to fix that by the swelling and slicing of a small piece of the emulsion sheet to watch the event from the side.

In our talk, we present newly developed methods, and the preliminary result about the above event.