Measurement of the Λ Spin-flipB(M1) Value in Hypernuclei

A hypernulear γ-ray spectroscopy experiment (E13) will be performed using K− beam at the K1.8 beam line of the J-PARC Hadron Experimental Facility in 2015. In this experiment, we will determine the B(M1) value of the Λ spin-flip transition of the ground state doublet in 19F to investigate the magnetic moment of a Λ hyperon in nuclei. In order to check the Λ performance of the whole spectrometer system of E13, a commissioning run was performed at the K1.8 beam line in 2013. We confirmed that the E13 setup is almost ready for the next beam time in 2015. In particular, new detectors for suppressing events from the two main K− decay modes in the on-line and off-line analyses are installed. As a result, the signal to noise ratio of gamma spectra is drastically improved, and the sensitivity to the B(M1) measurement is expected to increase.