Study of Double-strangeness Nuclear Systems with Nuclear Emulsion

Double strangeness nuclei such as double-Λ and Ξ hypernuclei have been studied with nuclear emulsion due to its fine position resolution. Recently, we have started an experiment to study Λ-Λ interaction more accurately than that information given by the NAGARA event with ∼102 double-Λ hypernuclei which may provide us understanding free from nuclear medium effect. It is necessary to develop treatment method for huge amount, 2.1 tons of the emulsion gel, even if very pure K− beams are available at J-PARC. We have developed the base film to support the emulsion, emulsion surface coating method with a special layer of 0.5 μm thick, method for making large-size plate (35.0 x 34.5 cm2) and scanning method, called “overall scanning”. The first evidence of a deeply bound state of Ξ--14N system, named KISO, was successfully detected in the test operation of the overall scanning.