I have analytically derived low-voltage approximations of tunes in RFQ with multiple radio frequencies to increase the efficiency of finding conditions of betatron resonances for isobar separation. The SCRIT (Self-Confining RI Ion Target) electron scattering facility has been aiming at the 132Sn-electron scattering, which requires eliminating an isobar, 132Sb, from the ion source. To achieve...
We are conducting simulations to improve ion bunch cooling efficiency for the development of an isobar separator for 132Sn and 132Sb using SCRIT. The goal is to cool 10^5 ions to room temperature within 1 ms and then extract them to MRTOF for isobar separation. The setup involves simulations using a quadrupole ion trap. By applying RF and DC, we change the potential to collect the cooled ions...
The SCRIT group aims to perform electron scattering experiments targeting short-lived radioactive nuclei using a novel internal target generation method (SCRIT method) in the electron storage ring. The target ions trapped in the SCRIT device have variable densities, so a luminosity monitor is required besides the scattered electron measurement system when targeting unstable nuclei with unknown...
Study of nuclei with exotic neutron to proton number ratios is one of the frontiers in the quantum many-body system of nucleons. To clarify the size and structure of neutron-rich and neutron-deficient nuclei, we have applied proton elastic scattering as a different probe from electron scattering. It is essential to determine the proton and neutron density distribution of neutron-rich and...
The excited states of nuclei near the N=50 and 82 closed shells can be well described by the shell model, thereby offering a suitable laboratory to test its predictions. Therefore, it has been attracting a large number of experimental and theoretical studies for these nuclei. Such studies are of great significance in providing information on the mechanism of particle-hole excitations of the...
A SCRIT (Self-Confining RI Ion Target) method is a target-forming technique in an electron storage ring for electron scattering experiments with unstable nuclei. A target ion beam with a charge state of 1+ is injected into a SCRIT device. They are trapped transversely by periodic focusing forces from electron beam bunches and longitudinally by the electrostatic well-potential in the SCRIT...
The charge density distributions of nuclei are best determined by elastic electron scattering, and the stable nuclei that have been studied so far have played an essential role in revealing their internal structure.
Recently it was pointed out theoretically that the 4th moment of the charge density distribution, <r_c^4>, contains the information of neutron-distribution radius^([1]).
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The SCRIT team aims to measure the structure of 132Sn in the future. However, they have already encountered some challenges, such as the isobar problem. The long-term goal of the Rikkyo University team is to use a multiple reflection time-of-flight mass spectrometer (MRTOF-MS) to accurately separate isobars with relative mass ‘dm/m=1/39783’. MRTOF is an instrument that measures the mass from...
To stabilize the ion trap and improve efficiency of SCRIT (Self-Confining RI Ion Target) experiment, it is essential to eliminate beam instability in the electron storage ring, SR2 (SCRIT-equipped Riken Storage Ring). The main cause of the beam instability is the Higher Order Modes (HOM) of the acceleration cavity induced by the wake field of the beam, which requires improvement of the...
In the 1950s, Bohr and Mottelson established the picture that most of heavy atomic nuclei deform into a prolate shape consisting of one long axis and two short axes of equal length. However, recent theoretical calculations by T. Otsuka et al. indicate that these nuclei prefer a triaxial shape, with all three axes having different lengths. Additionally, the presence of excited states due to...
