Development of dispersion matching optics of primary beam for SRC – BigRIPS system at RIBF*

We are developing dispersion matching optics for SRC – BigRIPS system at RIBF, aiming at systematic precision spectroscopy of pionic atoms via the (d, ³He) reaction and searching for double Gamow–Teller giant resonances via the (¹²C, ¹²Be(0₂⁺)) reaction.

We improve the measurement technique in the missing mass spectroscopy. Both experiments use primary beam and the same detector configuration for missing-mass spectroscopy. In these experiments, the largest contribution to the resolving power is a primary beam momentum spread. Therefore we develop a dispersion matching optical system to suppress the contribution from the momentum spread at the focal plane.

We performed machine study of beam transfer line (beam line for primary beam) and BigRIPS (beam line for secondary beam) at RIBF in June 2018 in order to achieve the dispersion matching condition. In this experiment, we estimated optical matrices in the beam transfer line based on the measured data by detectors located in the BigRIPS.

We report the results of the machine stydy and the future plan.