BigRIPS as a high resolution spectrometer for pionic atoms

We are presently working on a new project ‘pionic atom factory project' at RIBF. The project aims at precision spectroscopy of the energy spectrum of the pionic atom for a wide range of elements, using missing-mass spectroscopy of the (d,3He) reaction near the π^- emission threshold. For this project, we developed a new ion optics for BigRIPS using the dispersion-matching method. In this optics the BigRIPS beam line is used as a high resolving-power forward angle spectrometer to momentum-analyze ³He. We are aiming for a spectral resolution of <400 keV (FWHM). An overview of the new optics and the result of a pilot experiment are reported.