In 2022, we successfully measured the angular distribution of electron elastic scattering off 137Cs nuclei produced online at the SCRIT facility. I will present details of this experiment and prospects for the 132Sn experiment.
Electron scattering on radioactive nuclei could provide nuclear observables with an unprecedented radial sensitivity. In these nuclei, unique quantum phenomena occur but basic properties such as charge densities are still completely unknown. Precise densities extracted from the scattering data could be confronted to modern structure calculations. Such studies would provide better insight both...
Particle accelerators enable scientists to probe deeper into nuclei to extract key observables to validate or improve our nuclear theoretical frameworks. A fundamental quantity is the precise measurement of the nuclear charge radius. Electron scattering is the best tool to probe such quantity, with laser spectroscopy being a highly precise complementary technique that extends the reach to...
In electron scattering off unstable nuclei, the radioactive isotope (RI) beam production is
one of most important experimental parts. A low-energy high-quality RI beam with low emittance and small energy spread is needed for SCRIT. Furthermore, a high-intensity RI beam is also required in order to obtain a sufficient luminosity. To satisfy these requirements, we constructed an online isotope...
The Rare Isotope Accelerator complex for ON-line experiment (RAON) is being developed as the flagship Radioactive Isotope (RI) facility for fundamental research and applications in Korea. The initial objective of the RAON in nuclear physics is to expand the nuclear chart through the in-flight method with RI beams and the measurement of the properties of newly discovered isotopes. A high-power...
The SCRIT group is preparing to conduct an electron scattering experiment on 132Sn. However, isobaric contaminants in the ion beam present a significant challenge. To address this, we are developing a beam purification system based on the MRTOF (Multi-reflection time-of-flight) mass spectrograph. In this presentation, we will discuss the current status of the development, our plans, and the...
Traps have become indispensable tools for investigating the fundamental properties of atomic nuclei. Their widespread use at rare isotope facilities has generated a wealth of nuclear data, impacting not only nuclear physics but also related fields such as astrophysics, neutrino physics, and atomic physics. The IJCLab at Orsay has a long-standing tradition of developing such tools, and in this...
Recent theoretical studies indicate that triaxial deformation may occur in many nuclei including those having axially symmetric shapes in conventional view. I will present an overview of such a novel picture confirmed by the state-of-the-art large-scale shell-model (or CI) calculations. I will then talk about a possible experimental clarification for the case of 154Sm nucleus. This nucleus...
The proton radius puzzle, created by two disagreeing precision measurements in 2010, has been the focus of intense work efforts. With new results in the last decade, our understanding of the puzzle has evolved, but it has not been fully resolved yet. In the talk, I will give an overview over the current status of the puzzle, and discuss the current and future plans for measurements, with a...
In my presentation, I will discuss past and future measurements of the proton's electric form factor at MAMI and MESA and introduce a novel numerical approach for extracting the proton charge radius.
The proton charge radius is one of the most basic characteristics of the nucleons and is crucial for many applications such as the determination of the Rydberg constant, for QED tests, etc. Its determination is a hot topic in several physics communities as it has been reported close to 0.84 fm or 0.88 fm using electron scattering, atomic and muonic hydrogen spectroscopy. The proton charge...
The precision result of a deuteron charge radius measurement (2.12562(78) fm) using muonic deuterium spectroscopy has about the 3.5 sigma discrepancy with the average of ordinary deuterium spectroscopy (2.1415(45) fm); this resulted in the deuteron radius puzzle, but the result of electron scattering (2.13(1) fm) is too imprecise to distinguish this discrepancy. New, reliable, and precise...
In this work, the γZ-exchange contributions in the low-energy elastic parity violating ep scattering are discussed with the approximation me = 0, where me is the mass of electron. By expanding the γpp and Zpp interactions on the momentum of photon and considering both the leading-order and the next-to-leading order interactions, we calculate the amplitudes of the γZ-exchange diagrams. After...
Based on an integral method [Phys. Lett. B 808, 135669 (2020)], spatial moments of the proton charge density are determined by means of a global analysis of available proton electric form factor data from Rosenbluth separation and low squared four-momentum transfer experiments. Specific attention is paid to the evaluation of the systematic errors of the method, particularly the sensitivity to...
We present our recent results for nucleon elastic form factors obtained from 2+1 flavor lattice QCD at the physical point with a large spatial extent of about 10 fm. Our calculations are performed with the PACS10 gauge configurations generated by the PACS Collaboration with the six stout-smeared O(a) improved Wilson-clover quark action and Iwasaki gauge action at beta=1.82 and 2.00...
In this contribution, I present a recent theoretical study of the magnetic structure of light nuclei; namely, I will discuss the calculation of magnetic moments and form factors in $6\le A \le 10$ systems using the Norfolk model-- a chiral effective field theory based nuclear interaction-- and its consistent electromagnetic current operators. To study these observables, I employ quantum Monte...
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]).
...
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...
The isospin symmetry breaking part of the nuclear interaction is a small part of the whole; however, it sometimes gives important contributions to nuclear properties, such as the difference of mirror nuclei, the isobaric analog states, and the neutron-skin thickness. The isospin symmetry breaking terms also affect the estimation of the slope parameter of the nuclear symmetry energy.
In this...
In nuclear physics, electron scattering has been considered for studying proton distributions of nuclei so far.
I would like to talk about the investigation of the neutron distribution by electron scattering, in particular, focusing on unstable nuclei which will be done in future by low energy electron scattering.
Using the relativistic mean-field model with the isoscalar- and isovector-meson mixing, we consider a new nuclear equation of state, which satisfies the large neutron skin thickness of Pb208 and the small neutron-star radius, respectively reported by the PREX-2 experiment and the NICER observation. We study the effects of scalar-isovector meson and its mixing on the properties of...
The electron-nucleus scattering provides us with one of the clearest ways to investigate nuclear structure. The scattering cross is factorized as a product of the leptonic and nuclear parts. The nuclear part can be computed from the nuclear vector current operators. With chiral effective field theory, the current operators can also be derived systematically, the same as the nuclear...
The description of atomic nuclei based on ab initio methods that treat all nucleons as active has known tremendous progress over the past decades. In particular, the progress in interactions based on chiral effective field theory has lead to a more accurate description of bulk properties of nuclei such as density profiles and radii. In this talk, I will discuss recent developments that...
Inspired by the proton radius puzzle, the MUon Scattering Experiment (MUSE) at Paul Scherrer Institute (PSI) in Villigen, Switzerland, was introduced to provide new information by simultaneously measuring elastic scattering of electrons and muons, as well as positrons and antimuons from a liquid hydrogen target. MUSE aims to provide precise cross sections with extractions of the electric form...
The AMBER collaboration at CERN plans to measure muon-proton scattering at low momentum transfer, allowing for a precision determination of the proton charge radius. A muon beam of 100 GeV will impact on a pressurized hydrogen target, which serves at the same time as detector of the recoiling protons. The high beam energy allows for small systematic corrections, with strongly forward-boosted...
Precise lepton-proton (l-P) scattering experiments need similarly precise theory predictions. It is now possible to model electron-proton scattering at next-to-next-to-leading order (NNLO) in QED. These corrections can be similar in size or even larger than contributions that probe more in depth the nuclear structure, e.g. two-photon exchange corrections. Hence both kinds of contributions need...
I will describe our recent and ongoing work towards high-accuracy calculations of the electromagnetic form factors of light nuclei in the framework of chiral EFT.
Recent experiments using advanced laser spectroscopy technique revealed that the charge radii of neutron-deficient gold (Au), Hg and Pb isotopes exhibit significant changes in ground state deformation: odd-even shape staggering in the N = 98 ∼ 100 region and abrupt change of charge radii from N =108. In this study, we examine the abnormal shape evolution of the nuclear charge radii. We use...
Charge symmetry breaking (CSB) of nuclear force is a key for a precise description of masses of normal nuclei and hypernuclei. In this work, I introduce the CSB effect by omega-rho_0 meson mixing term, which describes a part of CSB effects in nucleon-nucleon and nucleon-hyperon interactions in a unified way, in a framework of relativistic mean-field model. I will discuss the effects of the...
The interaction cross section is one of the measurements from which the matter radii of nuclei can be derived. It can be applied to unstable nuclei very far from the stability line due to the large cross section and the ability to thick targets. It has contributed to the discovery of exotic halo structures, skin structures and new magic numbers of unstable nuclei. On the other hand, it has...
Proton elastic scattering at 197 MeV and 295 MeV from 90,92, 94 Zirconium were measured at RCNP Osaka Univ. . By analyzing double energy data we have succeeded to extract proton and neutron density distributions separately using medium modified RIA. Point proton densities obtained by proton scattering are compared with the results obtained by electro-magnetic probes.
Baryon density distribution is a fundamental information to understand the nuclear many body system. The ESPRI project is aimed at investigating the density distributions of not only stable but also unstalbe nuclei by using proton elastic scattering. Recent status and future plans of the project will be reported.
Nuclear contact is a key quantity to describe the nucleon-nucleon short-range correlations (SRCs). While they have been determined by electron scattering experiments for selected stable nuclei, nuclear contacts are largely unknown for unstable nuclei. In this work, we study nuclear contacts for a number of nuclei in the vicinity of the doubly magic 132Sn from the theoretical perspective, with...
Symmetry and its breaking are of great importance in physics and pervade every area of nature. The interplay between these symmetries is fundamental and of significance. As a many-body quantum system with the wealth of information on symmetries, the atomic nucleus is an ideal laboratory to study the fundamental symmetries breaking and their interplay. The present work provides the first test...
