The first elastic electron scattering has been successfully performed at the self-confining RI ion target (SCRIT) facility, the world's first electron scattering facility for exotic nuclei. The SCRIT technique achieved high luminosity (over 10 27 cm −2 s −1 , sufficient for determining the nuclear shape) with only 10 8 target ions. While 132 Xe used in this time as a target is stable isotope, the charge density distribution was firstly extracted from the momentum transfer distributions of the scattered electrons by comparing the results with those calculated by a phase shift calculation.The charge density distribution of the nucleus is one of the most important factors in the nuclear structure investigations, as it directly relates to the superimposition of the squared wave functions of all protons in the nucleus. Following the monumental measurements by R. Hofstadter and his colleagues [1] in the latter half of the 20th century, many stable nuclei have been studied by elastic electron scattering experiments. However, with few exceptions, electron scattering from short-lived unstable nuclei has been precluded by the difficulty in preparing the target material for these nuclei. Realizing electron scattering for unstable nuclei has been long waited, as it has been revealed that some of nuclei far from the stability valley exhibit exotic features such as neutron halo, neutron skin, etc.[2] which are totally unknown in stable nuclei.We have invented an internal target-forming technique called self-confining RI ion target (SCRIT) [3] in an electron storage ring, which three-dimensionally traps the target ions along the electron beam axis. The ions are confined by transverse focusing force given by the electron beam itself and an electrostatic potential well provided by electrodes put along the beam axis. After a successful feasibility study [4,5], we have recently completed the construction of the SCRIT electron scattering facility [6] at RIKEN's RI Beam Factory, which is dedicated to the study of exotic nuclei. The luminosity required for elastic electron scattering (10 27 cm −2 s −1 ) was achieved with only 10 8 target ions as available at an conventional isotope separation on line (ISOL) facility. In traditional electron scattering experiments, the number of target nuclei is typically of the order of 10 20 . This advancement enables electron scattering not only from unstable nuclei, but also from stable nuclei that have not been studied to date.In this Letter, we report the first elastic electron scattering results of 132 Xe nuclei obtained at the SCRIT facility. Although 132 Xe is a stable nucleus, it has never been investigated by electron scattering [7]. Interestingly, stable xenon isotopes have been recently utilized as targets for dark matter searches [8][9][10], and in neutrinoless double beta decay experiments [11]. To calculate the cross sections in these experiments, the form factors of the Xe isotopes are required. However, transition X-ray measurements of muonic atoms have yielded only the rootmean-squa...

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We carried out a demonstrative electron scattering experiment using a novel ion-trap target exclusively developed for short-lived highly unstable nuclei. Using stable 133Cs ion as a target, this experiment completely mimicked electron scattering off short-lived nuclei. Achieving a luminosity higher than 10;{26} cm;{-2} s;{-1} with around only 10;{6} trapped ions on the electron beam, the angular distribution of elastic scattering was successfully measured. This experiment clearly demonstrates that electron scattering off rarely produced short-lived nuclei is practical with this target technique.

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In the last two decades a number of nuclear structure and astrophysics experiments were performed at heavy-ion storage rings employing unique experimental conditions offered by such machines. Furthermore, building on the experience gained at the two facilities presently in operation, several new storage ring projects were launched worldwide. This contribution is intended to provide a brief review of the fast growing field of nuclear structure and astrophysics research at storage rings