Progress of the hypernuclear decay pion spectroscopy program at MAMI-C

We have performed high resolution spectroscopies for binding energies of light Λ hypernuclei with newly established experimental technique 'hypernuclear decay pion spectroscopy using electro-photo production'. We identified successfully a first decay pion peak from _Λ⁴H in 2012 experiment. A spectrometer Kaos for K⁺ tagger was upgraded and suppressed large positron background using a lead wall in the experiment. We performed the next generation experiment with higher statistics in 2014. In this experiment, we achieved twice higher beam intensity and doubled the length of the beam-time with a lower background rate thanks to improvements for the lead wall and a trigger system. (author)