Proton radii of 12−19 C densities derived from first accurate charge changing cross section measurements at 900A MeV with a carbon target are reported. A thick neutron surface evolves from ∼ 0.5 fm in 15 C to ∼ 1 fm in 19 C. The halo radius in 19 C is found to be 6.4±0.7 fm as large as 11 Li. Ab initio calculations based on chiral nucleon-nucleon and three-nucleon forces reproduce well the radii.

The first determination of radii of point proton distribution (proton radii) of (12-17)B from charge-changing cross sections (σ(CC)) measurements at the FRS, GSI, Darmstadt is reported. The proton radii are deduced from a finite-range Glauber model analysis of the σ(CC). The radii show an increase from ¹³B to ¹⁷B and are consistent with predictions from the antisymmetrized molecular dynamics model for the neutron-rich nuclei. The measurements show the existence of a thick neutron surface with neutron-proton radius difference of 0.51(0.11) fm in ¹⁷B.

A measurement of the reduced transition probability for the excitation of the ground state to the first 2 þ state in 104 Sn has been performed using relativistic Coulomb excitation at GSI. 104 Sn is the lightest isotope in the Sn chain for which this quantity has been measured. The result is a key point in the discussion of the evolution of nuclear structure in the proximity of the doubly magic nucleus 100 Sn. The properties of many composite quantum objects that represent building blocks of matter, such as hadrons, atomic nuclei, atoms, and molecules are governed by energy gaps between quantum states which originate in the forces between their fermionic constituents. In the case of atomic nuclei, the energy gaps manifest themselves by the existence of specific stable isotopes. These include, e.g., the double shell-closure nuclei 4 He, 16 O,40;48 Ca, and 208 Pb, which are particularly robust against particle separation and intrinsic excitation. The -unstable isotopes 56 Ni, 78 Ni, and 100;132 Sn are also expected to correspond to double shell closures. However, data for 78 Ni and 100 Sn are scarce due to their exotic neutron-to-proton ratios. Therefore, there is considerable interest in finding more proof for the magicity of these isotopes. In addition, the single particle energies relative to 100 Sn are largely unknown experimentally. Data are limited to the energy splitting between the two lowest-energy orbitals [1,2] while extrapolations from nearby nuclei are available with a typical uncertainty of a few hundred keV for the orbitals of higher energy [3]. Since 100 Sn is predicted to be a doubly magic nucleus, it would provide an approximately inert core on top of which simple excitations can be formed by adding few particles or holes. For this reason, it presents an ideal testing ground for fundamental nuclear models. Another cause for increased interest in nuclear structure in this region comes from the rp process of nuclear synthesis [4]. It has been concluded recently that this reaction sequence comes to an end near 100 Sn [4]. In addition, 100 Sn itself is expected to be the heaviest self-conjugate PRL 110,

Charge-changing cross sections at high energies are expected to provide useful information on nuclear charge radii. No reliable theory to calculate the cross section has yet been available. We develop a formula using Glauber and eikonal approximations and test its validity with recent new data on carbon isotopes measured at around 900A MeV. We first confirm that our theory reproduces the cross sections of 12,13,14 C + 12 C consistently with the known charge radii. Next we show that the cross sections of 12−19 C on a proton target are all well reproduced provided the role of neutrons is accounted for. We also discuss the energy dependence of the charge-changing cross sections. DOI: 10.1103/PhysRevC.94.011602 A study of unstable nuclei is one of the fields that have been promoted most intensively. Charge distribution or charge radius, among others, is one of the fundamental quantities to characterize the ground-state properties of nuclei. Electron scattering measurement is ideal for probing the distribution but so far not applicable to short-lived unstable nuclei. We note, however, that the electron-ion scattering experiment will be available in the near future, as planned in Refs. [1,2]. Isotope shift measurement allows us to precisely deduce the charge (proton) radius for some limited unstable nuclei. The measurement of the charge-changing cross section (CCCS) newly appears as a potential means to extract the proton radius since it has the great advantage that the cross section can be measured for almost all nuclei by the same setup as the total reaction or interaction cross section that plays a decisive role in determining the nuclear matter radius [3]. In fact the CCCS has recently been measured to get information on the proton radii of light unstable nuclei [4][5][6][7][8].A theoretical tool for extracting the matter radius from the high-energy total reaction cross sections is well established with the help of Glauber theory [9]. See Refs. [10,11] for a useful application to determining both proton and neutron radii. The reaction mechanism for the charge-changing reaction (CCR) is, however, not well understood and energydependent adjustments are introduced to analyze the CCCS data [4][5][6]12], which makes it difficult to obtain proton radii from the measurement. The purpose of this paper is to show * Present address: Department of Physics, Niigata University, Niigata 950-2181, Japan.that recent new CCCS data of carbon isotopes on both 12 C [13] and proton targets are all satisfactorily reproduced in the framework of the Glauber and eikonal models. The role of neutrons becomes evident for the proton target. This is an important step toward constructing a method of analyzing CCCSs with the use of no adjustable parameters.The total reaction cross section can be calculated bywhere b is a two-dimensional (2D) impact parameter vector perpendicular to the beam (z) direction, |0 = |0 P 0 T is a product of the projectile and target ground-state wave functions, and, e.g., χ p is a sum of the phase-shift functions χ...

The charge-changing cross sections of 7,[9][10][11][12]14 Be have been measured at 900A MeV on a carbon target. These cross sections are discussed both in terms of a geometrical and a Glauber model. From several different analyses of the cross sections, the proton distribution radius (proton radius) of 14 Be is determined for the first time to be 2.41 ± 0.04 fm. A large difference in the proton and neutron radii is found. The proton radii are compared to the results of fermionic molecular dynamics (FMD) and antisymmetrized molecular dynamics (AMD) calculations.