25–29 Sept 2017
Salamanca, Spain
Europe/Zurich timezone

S=-2 Systems

25 Sept 2017, 16:45
25m
Aula 2.7

Aula 2.7

Talk Hadrons in matter including hypernuclei Hadrons in matter including hypernuclei

Speaker

Prof. Tomofumi Nagae (Kyoto University)

Description

At J-PARC, we are conducting spectroscopic studies of strangeness -2 systems, such as Ξ- and double-Λ hypernuclei. The experimental information on these systems is so far
limited with several emulsion events; the “Nagara” event for ΛΛ6He and the “Kiso” event
for a strong candidate of a Ξ hypernucleus. In this talk, I will introduce a preliminary result
on Ξ12Be obtained in the pilot run of E05 experiment in 2015, and the status of E07
experiment, a hybrid-emulsion measurement, taking the data just recently in 2017.
In the E05 experiment, we are going to measure the Ξ12Be spectrum with an energy
resolution of better than 2 MeV(FWHM) by constructing a new spectrometer S-2S. Before
the completion of the S-2S, we measured an excitation energy spectrum of the 12C(K-,K+)X
reaction at 1.8 GeV/c with an energy resolution of 6 MeV, which is the best energy
resolution ever achieved in studying this reaction. The measurement was performed at the
K1.8 beam line of the J-PARC hadron experimental hall by using the SKS spectrometer.
The K- beam intensity at the primary proton beam power of 39 kW was typically 6x105/
spill with 5.5-sec. beam cycle. The energy resolution was estimated from the peak observed
in the p(K-,K+)Ξ- reaction from a 9.54-g/cm2 CH2 target. We took the data on the
12C(K-,K+)X reaction with a 9.4-g/cm2 C target for about 10 days. We have observed about
60k events of quasi-free Ξ- production, and several tens of events in the bound region.
Although the analysis is still preliminary, we could see clear enhancements in the bound
region above a flat background. The up-to-date analysis result will be presented.
In June, 2017, we have successfully completed the E07 data taking exposing a lot of
stacks of emulsions. We estimate the number of stopped Ξ events would be an order of
magnitude larger than ever. The data taking conditions and prospect of the data analysis
will be reported.

Author

Prof. Tomofumi Nagae (Kyoto University)

Presentation materials