First Observation of Electron Scattering from Online-Produced Radioactive Target

We successfully performed electron scattering off unstable nuclei which were produced online from the photofission of uranium. The target Cs137 ions were trapped with a new target-forming technique that makes a high-density stationary target from a small number of ions by confining them in an electron storage ring. After developments of target generation and transportation systems and the beam stacking method to increase the ion beam intensity up to approximately 2×107 ions per pulse beam, an average luminosity of 0.9×1026 cm−2 s−1 was achieved for Cs137. The obtained angular distribution of elastically scattered electrons is consistent with a calculation. This success marks the realization of the anticipated femtoscope which clarifies the structures of exotic and short-lived unstable nuclei.Received 7 March 2023Accepted 21 June 2023DOI:https://doi.org/10.1103/PhysRevLett.131.092502© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasForm factorsNuclear charge distributionNuclear shapes and momentsTechniquesParticle sources & targetsRadioactive beamsNuclear Physics