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The existence of magic numbers of protons and neutrons in nuclei is essential for understanding nuclear structure and fundamental nuclear forces. Over decades, researchers have conducted theoretical and experimental studies on the new magic number Z(N) = 6, focusing on observables such as radii, binding energy, electromagnetic transition, and nucleon separation energies. We perform the ab initio no-core shell model calculations for the occupation numbers of the lowest single particle states in the ground states of Z(N) = 6 and Z(N) = 8 isotopes (isotones). Our calculations do not support Z(N) = 6 as a magic number over a span of atomic numbers. However, 14C and 14O exhibit the characteristics of double-magic nuclei.

We report the charge-changing cross sections ($\sigma_{\text{cc}}$) of 24 $p$-shell nuclides on both hydrogen and carbon at about 900$A$ MeV, of which $^{8,9}$Li, $^{10\textendash12}$Be, $^{10,14,15}$B, $^{14,15,17\textendash22}$N and $^{16}$O on hydrogen and $^{8,9}$Li on carbon are for the first time. Benefiting from the data set,we found a new and robust relationship between the scaling factor of the Glauber model calculations and the separation energies of the nuclei of interest on both targets.This allows us to deduce proton radii ($R_p$) for the first time from the cross sections on hydrogen. Nearly identical $R_p$ values are deduced from both target data for the neutron-rich carbon isotopes, however, the $R_p$ from the hydrogen target is systematically smaller in the neutron-rich nitrogen isotopes.This calls for further experimental and theoretical investigations., Comment: 5 pages, 3 figures

Electric quadrupole (E2) moments and transitions provide measures of nuclear deformation and related collective structure. However, matrix elements of the E2 operator are sensitive to the nuclear wave function at large distances and are poorly convergent within the ab initio no-core shell model approach. We demonstrate for the first time that the ratio of neutron to proton quadrupole transition matrix elements, Mn/Mp, is well-converged in the ab initio no-core shell model and provides a new and robust tool for comparing with experimental results. We find that our parameter-free results for Mn/Mp for the carbon isotopes and 10Be compare well with experiment, where available, and offer new insight into the quadrupole dynamics of nuclear response.

Periodic nanoparticle arrays can support surface lattice resonances (SLRs), which arise from the hybridization between localized surface plasmons (LSPs) and diffractive Rayleigh anomalies (RAs). In contrast to LSPs, SLRs enjoy a much higher quality (Q) factor. As the Q factor depends on many system parameters, a good understanding of them is essential for optimization. Here, we study the dependence of the Q factor of SLR from 2D Au nanorod arrays on nanorod orientation. It is found the Q factor is 112 when the nanorod is lying perpendicular to the incident plane but gradually increases by more than 13 times to 1460 upon rotating it azimuthally. The increase of the Q factor is due to the interplay between the coupling strength and the frequency detuning between the LSP and RA as well as the decay rate of the LSP. By optimizing these parameters, we can achieve a Q factor reaching over 12000, which is 6 times higher than the best reported so far.

Spectroscopic factors involving well bound nucleons in light nuclei are calculated with standard shell model, no-core shell model and Gamow shell model. Continuum coupling is included exactly in the Gamow shell model, due to the use of the Berggren basis, which contains bound, resonance and scattering states. Conversely, it is absent from standard and no-core shell models, where a basis of harmonic oscillator states is used. As the A - 1 nuclei for which spectroscopic factors are calculated are either weakly bound or unbound, coupling to continuum is prominent, even though the A nuclei are well bound. It is then showed that Gamow shell model can properly reproduce experimental data and is a predictive tool for detailed nuclear structure at drip-line, contrary to standard and no-core shell model.

Bloch waves in 1D periodic systems carry Zak phase, which plays a key role in determining the band topology. In general, for systems that possess inversion symmetry, the Zak phase of an isolated band is quantized as 0 or Pi and is associated with the spatial field symmetries at the Brillouin zone center and boundary. The phase is Pi if the field symmetries are different but is 0 when they are the same. Since the radiation losses from leaky systems are strongly associated with the Bloch waves, one may probe the far-field continuum to determine the Zak phases. Here, we formulate the diffractions from photonic systems at the zone center and boundary and find their spectral profiles reveal the Bloch wave symmetries and thereby the corresponding Zak phase. The field symmetries also generalize the occurrence of bound states in the continuum at high symmetry points. For verification, we have studied the Zak phases of one-dimensional TM plasmonic and TE photonic crystals by electrodynamic simulations and measuring the optical properties of plasmonic crystals using Fourier space diffraction spectroscopy and common path interferometry. In addition, a topological protected interface state is demonstrated when two 0 and Pi systems are joined together. The results prove our method provides a simple way for characterizing the band topology of non-Hermitian systems via far-fields.

The root mean square radii of the proton density distribution in $^{16-24}$O derived from measurements of charge changing cross sections with a carbon target at $\sim$900$A$ MeV together with the matter radii portray thick neutron skin for $^{22 - 24}$O despite $^{22,24}$O being doubly magic. Imprints of the shell closures at $N$ = 14 and 16 are reflected in local minima of their proton radii that provide evidence for the tensor interaction causing them. The radii agree with it ab initio calculations employing the chiral NNLO$_{\mathrm{sat}}$ interaction, though skin thickness predictions are challenged. Shell model predictions agree well with the data., Comment: 6 pages, 3 figures, accepted for publication in Physical Review Letters

Electroless nickel plating is an established industrial process that provides a robust and relatively low-cost coating suitable for transporting and storing ultracold neutrons (UCN). Using roughness measurements and UCN-storage experiments we characterized UCN guides made from polished aluminum or stainless-steel tubes plated by several vendors. All electroless nickel platings were similarly suited for UCN storage with an average loss probability per wall bounce of $2.8\cdot10^{-4}$ to $4.1\cdot10^{-4}$ for energies between 90 neV and 190 neV, or a ratio of imaginary to real Fermi potential $\eta$ of $1.7\cdot10^{-4}$ to $3.3\cdot10^{-4}$. Measurements at different elevations indicate that the energy dependence of UCN losses is well described by the imaginary Fermi potential. Some special considerations are required to avoid an increase in surface roughness during the plating process and hence a reduction in UCN transmission. Increased roughness had only a minor impact on storage properties. Based on these findings we chose a vendor to plate the UCN-production vessel that will contain the superfluid-helium converter for the new TRIUMF UltraCold Advanced Neutron (TUCAN) source, achieving acceptable UCN-storage properties with ${\eta=3.5(5)\cdot10^{-4}}$., Comment: 8 pages, 7 figures

Optical chirality (OC) is a fundamental property of electromagnetic waves that plays a key role in governing chiral light-matter interaction. Here, we demonstrate how to obtain superchiral surface lattice resonances (SLRs), which arise from the hybridization between localized surface plasmons (LSPs) and diffractive Rayleigh anomalies (RAs), in nanoparticle arrays. We first study the coupling constants between LSPs and RAs in 2D Au monopartite nanorod arrays by angle-resolved reflectivity spectroscopy and finite-difference time-domain (FDTD) simulations. The complex dispersion relations and the near-fields of SLRs are then analyzed by temporal coupled-mode theory (CMT) for formulating the dependence of the coupling constants on the dipole orientation of the nanorod. The TE and TM coupling constants are found to depend strongly on the orientation of the dipole lying in the plane perpendicular to the propagation direction of RA. By using two orthogonally oriented nanorods, TE- and TM-SLRs can be excited independently. We then extend the CMT approach to rationally design superchiral SLRs based on 3D bipartite nanorods. The OC is shown to depend on the relative displacement between two nanorods, the near-field strength, and the interplay between the coupling constants and the Q-factor of the SLR resonance. We have achieved an averaged OC of 27 times stronger than that of the circularly polarized plane wave over the entire surface, featuring large area chiral surface waves that are useful for chirality-based applications., Comment: 32 pages, 15 figures

In analogous to the Su-Schrieffer-Heeger (SSH) model, one-dimensional (1D) electromagnetic (EM) crystals can exhibit nontrivial topological properties. In particular, when a nontrivial EM crystal is in contact with its trivial counterpart, a topologically protected interface state is formed. While much attention has been focused on single interface state, multiple interface states can interact collectively when under suitable conditions, giving rise to trivial or nontrivial band topologies resembling to the standard SSH model. Here, we study the topological properties of 1D metallic superlattices that support multiple interface states. We first demonstrate single interface state exists at the boundary between two topologically distinct metallic arrays that carry Bloch-like surface plasmon polaritons. Such interface state is then used as the building block for further constructing the superlattices. By exploiting the separation between two dimerized interface states and the distinct inter- and intra-interface configurations to facilitate different intracell and intercell interactions, we vary the band topology of the superlattices. More importantly, new superlattice interface state is formed when trivial and nontrivial superlattices are brought together. The superlattice interface state is found to have smaller angular divergence and longer localization length than its single counterpart, thus is desired for robust signal transmission and high finesse cavity.

We study the topological photonic states in one-dimensional (1-D) lattices analogue to the Su-Schrieffer-Heeger (SSH) model beyond the dipole approximation. The electromagnetic resonances of the lattices supported by near-field interactions between the plasmonic nanoparticles are studied analytically with coupled dipole--quadrupole method. The topological phase transition in the bipartite lattices is determined by the change of Zak phase. Our results reveal the contribution of quadrupole moments to the near-field interactions and the band topology. It is found that the topological edge states in non-trivial lattices have both dipolar and quadrupolar nature. The quadrupolar edge states are not only orthogonal to the dipolar edge states, but also spatially localized at different sublattices. Furthermore, the quadrupolar topological edge states, which coexist at the same energy with the quadrupolar flat band have shorter localization length and hence smaller mode volume than the conventional dipolar edge states. The findings deepen our understanding in topological systems that involve higher-order multipoles, or in analogy to the wave functions in quantum systems with higher-orbital angular momentum, and may be useful in designing topological systems for confining light robustly and enhancing light-matter interactions., Comment: 18 pages, 17 figures; submitted to Physical Review Research (Regular Article); revised version

An in-flight beam of $^{16}$N was produced via the single-neutron adding ($d$,$p$) reaction in inverse kinematics at the recently upgraded Argonne Tandem Linear Accelerator System (ATLAS) in-flight system. The amount of the $^{16}$N beam which resided in its excited 0.120-MeV $J^{\pi}=0^-$ isomeric state (T$_{1/2}\approx5$ $\mu$s) was determined to be 40(5)% at a reaction energy of 7.9(3) MeV/$u$, and 24(2)% at a reaction energy of 13.2(2) MeV/$u$. The isomer measurements took place at an experimental station $\approx30$ m downstream of the production target and utilized an Al beam-stopping foil and a HPGe Clover detector. Composite $^{16}$N beam rate determinations were made at the experimental station and the focal plane of the Argonne in-flight radioactive ion-beam separator (RAISOR) with Si $\Delta$E-E telescopes. A Distorted Wave Born Approximation (DWBA) approach was coupled with the known spectroscopic information on $^{16}$N in order to estimate the relative $^{16}$N isomer yields and composite $^{16}$N beam rates. In addition to the observed reaction-energy dependence of the isomer fraction, a large sensitivity to angular acceptance of the recoils was also observed., Comment: 21 pages, 7 figures

The isomeric state of $^{16}$N was studied using the $^{16}$N$^{g,m}$($d$,$^3$He)~proton-removal reactions at \mbox{11.8~MeV/$u$} in inverse kinematics. The $^{16}$N beam, of which 24% was in the isomeric state, was produced using the ATLAS in-fight facility and delivered to the HELIOS spectrometer, which was used to analyze the $^{3}$He ions from the ($d$,$^{3}$He) reactions. The simultaneous measurement of reactions on both the ground and isomeric states, reduced the systematic uncertainties from the experiment and in the analysis. A direct and reliable comparison of the relative spectroscopic factors was made based on a Distorted-Wave Born Approximation approach. The experimental results suggest that the isomeric state of $^{16}$N is an excited neutron-halo state. The results can be understood through calculations using a Woods-Saxon potential model, which captures the effects of weak-binding., Comment: 8 pages, 7 figurs

Charge-changing cross sections $\sigma_\mathrm{CC}$ for $^{42\textrm{--}51}$Ca on a carbon target at around 280~MeV/nucleon have been measured. The measured $\sigma_\mathrm{CC}$ values differ significantly from the previously developed calculations based on the Glauber model. However, through introduction of the charged-particle evaporation effect induced by the neutron-removal reaction in addition to the Glauber-model calculation, experimental $\sigma_\mathrm{CC}$ values on $^{12}$C at around 300~MeV/nucleon for nuclides from C to Fe isotopes are all reproduced with approximately 1\% accuracy. This proposed model systematically reproduces $\sigma_\mathrm{CC}$ data without phenomenological corrections, and can also explain experimental $\sigma_\mathrm{CC}$ values obtained in other energy regions., Comment: 13 pages, 11 figures

The electromagnetic character of the $\Delta I=1$ transitions connecting the one- to zero-phonon and the two- to one-phonon wobbling bands should be dominated by an $E2$ component, due to the collective motion of the entire nuclear charge. In the present work it is shown, based on combined angular correlation and linear polarization measurements, that the mixing ratios of all analyzed connecting transitions between low-lying bands in $^{135}$Pr interpreted as zero-, one-, and two-phonon wobbling bands, have absolute values smaller than one. This indicates predominant $M1$ magnetic character, which is incompatible with the proposed wobbling nature. All experimental observables are instead in good agreement with quasiparticle-plus-triaxial-rotor model calculations, which describe the bands as resulting from a rapid re-alignment of the total angular momentum from the short to the intermediate nuclear axis.

Surface lattice resonance (SLR) is the collective excitation of nanoparticle resonances arising from the hybridization between localized surface plasmons (LSPs) and propagating Rayleigh anomalies (RAs). When comparing with the corresponding LSPs, SLRs exhibit much higher quality factor. In fact, as the quality factor depends on the constituting resonances and their hybridization, how one can parametrize it in an analytic form is an important issue. We have studied the SLRs arising from 2D Au monopartite nanoparticle arrays by angle- and polarization-resolved reflectivity spectroscopy, temporal coupled mode theory (CMT) and finite-difference time-domain (FDTD) simulation. The scattering matrix of the SLRs is formulated, revealing the importance of the spectral detuning and the interaction strengths between the LSP and the RAs in governing the quality factor. We then extend the CMT approach to study bipartite arrays where nanoparticle dimer is employed and find the coupling between two LSPs plays a major role in further boosting the quality factor. Specifically, the coupling takes part in controlling the detuning factor as well as determining whether the coupled bright or dark mode is hybridized with the RAs. The dark mode hybridization can strongly enhance the quality factor which is otherwise not possible in the monopartite counterparts., Comment: 33 pages, 10 figures

We present a precise measurement of the cross section, proton and $\rm ^3He$ analyzing powers, and spin correlation coefficient $C_{y,y}$ for $p$-$\rm ^3He$ elastic scattering near 65 MeV, and a comparison with rigorous four-nucleon scattering calculations based on realistic nuclear potentials and a model with $\Delta$-isobar excitation. Clear discrepancies are seen in some of the measured observables in the regime around the cross section minimum. Theoretical predictions using scaling relations between the calculated cross section and the $\rm ^3 He$ binding energy are not successful in reproducing the data. Large sensitivity to the $NN$ potentials and rather small $\Delta$-isobar effects in the calculated cross section are noticed as different features from those in the deuteron-proton elastic scattering. The results obtained above indicate that $p$-$\rm ^3He$ scattering at intermediate energies is an excellent tool to explore nuclear interactions not accessible by three-nucleon scattering., Comment: 22 pages, 6 figures

A resonant state at $3.21^{+0.12}_{-0.04}$\,MeV, located just above the one-neutron separation threshold, was observed for the first time in $^{12}$Be from the $^{11}$Be\,$(d,p)^{12}$Be one-neutron transfer reaction in inverse kinematics. This state is assigned a spin-parity of $0^-$, according to the distorted-wave Born approximation (DWBA) and decay-width analysis. Gamow coupled-channel (GCC) and Gamow shell-model (GSM) calculations show the importance of the continuum-coupling, which dramatically influences the excitation energy and ordering of low-lying states. Various exotic structures associated with cross-shell intruding configurations in $^{12}$Be and in its isotonic nucleus $^{11}$Li are comparably discussed.

Experimental results of the $p(^{13}{\rm B},d)^{12}{\rm B}$ transfer reaction to the low-lying states in $^{12}$B are reported. The optical potential parameters for the entrance channel are extracted from the elastic scattering $p$($^{13}{\rm B}$, $p$) measured in the same experiment, while those for the exit channel are global ones. Spectroscopic factors associated with the $p$-, $s$-, and $d$-wave neutron transfer to the known $^{12}$B states, are extracted by comparing the deuteron angular distributions with the calculation results. The separated $s$- and $d$-wave intruder strengths in $^{13}{\rm B}_{\rm g.s.}$ were determined to be $10(2)\%$ and $6(1)\%$, respectively, which follow roughly the systematics for the $N$ = 8 neutron-rich isotones. The measured total intruder strength is in good agreement with the shell model calculation, while the individual ones evolve quite differently. Particularly, the sudden change of the $d$-wave intensity between $^{13}$B and $^{12}$Be needs further theoretical interpretation., Comment: 8 pages,8 figures

Precession is a unique motion in which the orientation of the rotational axis of a rotating body is not fixed but moving, and it generally exists in the Universe from giant stars through tiny atomic nuclei. In principle, the precession of an atomic nuclide can be approximately described as wobbling motion, arising from the coupling of a rotation and a harmonic vibration. Recently, a number of wobbling bands were reported at low spin, which violate the wobbling approximation that can be valid only at high spin. Here we explore the nature of the reported low-spin wobbling bands. Via a new experiment, we demonstrate that one such band in $^{187}$Au is generated by dominant single-particle excitation rather than by the excitation of a wobbling phonon. We point out that the imperfect research paradigm used previously would lead to unreliable identification of low-spin wobbling bands. Consequently, new experimental approaches should be developed to distinguish among the different excitation mechanisms that can give rise to the observed low-spin bands in odd-even nuclei.

The broken mirror symmetry in subwavelength photonic systems has manifested many interesting chiroptical effects such as optical rotation and circular dichroism. When such systems are placed periodically in a lattice form, in addition to intrinsic chirality, extrinsic chirality also takes part, and the overall effect depends not only on the basis and lattice but also the excitation configuration. Here, we study planar chiral nanohole arrays in square lattice that support Bloch-like surface plasmon polaritons (SPPs) and clarify how the system geometry and the excitation contribute to circular dichroism. By using temporal coupled mode theory (CMT), the dissymmetry factor and the scattering matrix of the arrays are analytically formulated. Remarkably, we find the dissymmetry factor depends only on the coupling polarization angle and the in-coupling phase difference between the p- and s-polarizations. Besides, the upper limit of the dissymmetry factor at +/-2 can be reached simply by orienting the lattice of the arrays for properly exciting the Bloch-like SPPs and at the same time making the basis mimic two orthogonal and relatively displaced dipoles, demonstrating the interplay between extrinsic and intrinsic chirality. The models have been verified by numerical simulations and experiments, yielding the dissymmetry factors to be 1.82 and 1.55, respectively, from the proposed dual slot system., Comment: 29 pages, 11 figures

Inelastic proton scattering experiments were performed at the Research Center for Nuclear Physics, Osaka, with a 295 MeV beam covering laboratory angles 0{\deg}-6{\deg} and excitation energies 6-22 MeV. Cross sections due to E1 and M1 excitations were extracted with a multipole decomposition analysis and then converted to reduced transition probabilities with the "virtual photon method" for E1 and the "unit cross section method" for M1 excitations, respectively. Including a theory-aided correction for the high excitation energy region not covered experimentally, the electric dipole polarizability was determined from the E1 strength distributions. Total photoabsorption cross sections derived from the E1 and M1 strength distributions show significant differences compared to those from previous ($\gamma$,xn) experiments in the energy region of the isocvector giant dipole resonance (IVGDR). The widths of the IVGDR deduced from the present data with a Lorentz parameterization show an approximately constant value of about 4.5 MeV in contrast to the large variations between isotopes observed in previous work. The IVGDR centroid energies are in good correspondence to expectations from systematics of their mass dependence. Furthermore, a study of the dependence of the IVGDR energies on bulk matter properties is presented. The E1 strengths below neutron threshold show fair agreement with results from ($\gamma$,$\gamma$') experiments on 112,116,120,124Sn in the energy region between 6 and 7 MeV. At higher excitation energies large differences are observed pointing to a different nature of the excited states with small ground state branching ratios. The isovector spin-M1 strengths exhibit a broad distribution between 6 and 12 MeV in all studied nuclei., Comment: 32 pages, 23 figures, submitted to Phys. Rev. C

We report the measurement of reaction cross sections ($\sigma_R^{\rm ex}$) of $^{27,29}$F with a carbon target at RIKEN. The unexpectedly large $\sigma_R^{\rm ex}$ and derived matter radius identify $^{29}$F as the heaviest two-neutron Borromean halo to date. The halo is attributed to neutrons occupying the $2p_{3/2}$ orbital, thereby vanishing the shell closure associated with the neutron number $N = 20$. The results are explained by state-of-the-art shell model calculations. Coupled-cluster computations based on effective field theories of the strong nuclear force describe the matter radius of $^{27}$F but are challenged for $^{29}$F., Comment: 8 pages, 4 figures

The dipole polarizability of stable even-mass tin isotopes 112,114,116,118,120,124 was extracted from inelastic proton scattering experiments at 295 MeV under very forward angles performed at RCNP. Predictions from energy density functionals cannot account for the present data and the polarizability of 208Pb simultaneously. The evolution of the polarizabilities in neighboring isotopes indicates a kink at 120Sn while all model results show a nearly linear increase with mass number after inclusion of pairing corrections., Comment: 10 pages, 6 figures, submitted to Phys. Lett. B

Inelastic ${}^{6}$Li scattering at 100 MeV/u on ${}^{12}$C and ${}^{93}$Nb have been measured with the high-resolution magnetic spectrometer Grand Raiden. The magnetic-rigidity settings of the spectrometer covered excitation energies from 10 to 40 MeV and scattering angles in the range $0^\circ < \theta_{\text{lab.}}< 2^\circ$. The isoscalar giant monopole resonance was selectively excited in the present data. Measurements free of instrumental background and the very favorable resonance-to-continuum ratio of ${}^{6}$Li scattering allowed for precise determination of the $E0$ strengths in ${}^{12}$C and ${}^{93}$Nb. It was found that the monopole strength in ${}^{12}$C exhausts $52 \pm 3^\text{(stat.)} \pm 8 ^\text{(sys.)}$\% of the energy-weighted sum rule (EWSR), which is considerably higher than results from previous $\alpha$-scattering experiments. The monopole strength in ${}^{93}$Nb exhausts $92 \pm 4^\text{(stat.)} \pm 10 ^\text{(sys.)}$\% of the EWSR, and it is consistent with measurements of nuclei with mass number of $A\approx90$. Such comparison indicates that the isoscalar giant monopole resonance distributions in these nuclei are very similar, and no influence due to nuclear structure was observed., Comment: 6 Figures

We have constructed and tested a novel plastic-scintillator-based solid-state active proton target for use in nuclear spectroscopic studies with nuclear reactions induced by an ion beam in inverse kinematics. The active target system, named Stack Structure Solid organic Scintillator Active Target (S4AT), consists of five layers of plastic scintillators, each with a 1-mm thickness. To determine the reaction point in the thickness direction, we exploit the difference in the energy losses due to the beam particle and the charged reaction product(s) in the scintillator material. S4AT offers the prospect of a relatively thick target while maintaining a good energy resolution. By considering the relative energy loss between different layers, the energy loss due to unreacted beam particles can be eliminated. Such procedure, made possible by the multi-layer structure, is essential to eliminate the effect of unreacted accompanying beam particles, thus enabling its operation at a moderate beam intensity of up to a few Mcps. We evaluated the performance of S4AT by measuring the elastic proton-proton scattering using a 70-MeV proton beam at Cyclotron and Radioisotope Center (CYRIC), Tohoku University., Comment: 32 pages, 14 figures

Interaction cross sections for $^{42\textrm{-}51}$Ca on a carbon target at 280 MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number $N=28$. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and the Mean-Field calculations point out that this anomalous enhancement of the nuclear size beyond $N=28$ results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare $^{48}$Ca core in Ca isotopes beyond $N=28$., Comment: 6 pages, 3 figures

Proton-3He scattering is one of the good probes to study the T=3/2 channel of three--nucleon forces. We have measured 3He analyzing powers for p-3He elastic scattering with the polarized 3He target at 70 and 100 MeV. The data are compared with the theoretical predictions based on the modern nucleon--nucleon potentials. Large discrepancies are found between the data and the calculations at the angles where the 3He analyzing power takes the minimum and maximum values, which are not explained by taking into account Delta-isobar degrees of freedom., Comment: 7pages, 3 figures Submission to SciPost

Elastic and inelastic alpha scatterings on $^{10}$C were measured using a 68-MeV/u radioactive $^{10}$C beam incident on the recently developed MAIKo active target system. The phenomenological effective $\alpha$-$N$ interaction and the point-nucleon density distribution in the ground state were determined from the elastic scattering data. The cross sections of the inelastic alpha scattering were calculated using this interaction and density distribution and were compared with the experiment to determine the neutron quadrupole transition matrix element $M_{n}$ between the ground state and the $2_{1}^{+}$ state at $E_{x} = 3.35$ MeV in $^{10}$C. The deduced neutron transition matrix element is $M_{n} = 6.9\, \pm0.7\, \mathrm{(fit)}\, \pm1.2\, \mathrm{(sys)}$ fm$^{2}$. The ratio of the neutron transition strength to proton transition strength was determined as $M_{n}/M_{p} = 1.05\, \pm0.11\, \mathrm{(fit)}\, \pm0.17\, \mathrm{(sys)}$, which indicates that the quadrupole transition between the ground state and the $2_{1}^{+}$ state in $^{10}$C is less neutron dominant compared to that in $^{16}$C., Comment: 13 pages, 10 figures, 2 tables. The title and conclusion have changed from the previous version

A new paradigm for nuclear structure that includes blocking effects of tensor interactions is proposed. All of the recently discovered magic numbers (N=6, 14, 16, 32 and 34) in neutron-rich nuclei can be explained by the blocking effects. A large amount of binding energy is gained by high-momentum correlated pairs of nucleons produced by the tensor interaction. Such tensor correlations strongly depend on the configuration space available for exciting nucleons to 2p-2h states. When additional neutrons occupy a new orbital, the previously available configuration may be lost, resulting in a sudden loss of binding energy otherwise gained by the 2p-2h excitations. Such tensor blocking effects enlarge the energy gaps at all observed new magic numbers. Tensor blocking also explains consistently the observed peculiar configurations of neutron-rich nuclei at the borders of shells., Comment: 8 pages, 2 figures, 1 table

A thick neutron skin emerges from the first determination of root mean square radii of the proton distributions for $^{17-22}$N from charge changing cross section measurements around 900$A$ MeV at GSI. Neutron halo effects are signaled for $^{22}$N from an increase in the proton and matter radii. The radii suggest an unconventional shell gap at $N$ = 14 arising from the attractive proton-neutron tensor interaction, in good agreement with shell model calculations. $Ab$ $initio$, in-medium similarity re-normalization group, calculations with a state-of-the-art chiral nucleon-nucleon and three-nucleon interaction reproduce well the data approaching the neutron drip-line isotopes but are challenged in explaining the complete isotopic trend of the radii., Comment: 18 pages, 3 figures

The isospin character of p-n pairs at large relative momentum has been observed for the first time in the 16O ground state. A strong population of the J,T=1,0 state and a very weak population of the J,T=0,1 state were observed in neutron pick up domain of 16O(p,pd) at 392 MeV. This strong isospin dependence at large momentum transfer is not reproduced by the distorted-wave impulse approximation calculations with known spectroscopic amplitudes. The results indicate the presence of high-momentum protons and neutrons induced by the tensor interactions in ground state of 16O., Comment: 12 pages, 4 figures, accepted for publication in Physical Review Letters

A new active target named MAIKo (Mu-PIC based Active target for Inverse Kinematics$_{\circ}$) has been developed at Kyoto University and Research Center for Nuclear Physics (RCNP), Osaka University. MAIKo is suited for missing-mass spectroscopy of unstable nuclei at forward scattering angles in inverse kinematics. MAIKo consists of a time projection chamber (TPC), which incorporates a micro-pixel chamber ($\mu$-PIC) as the electron multiplication and collection system. In MAIKo, the medium gas also plays the role of a reaction target, thus allowing detection of low-energy recoil particles with high position resolution. The MAIKo TPC was commissioned with He(93%)+iso-C$_{4}$H$_{10}$(7%) and He(93%)+CO$_{2}$(7%) mixture gasses at 430 hPa. The gas gain and the angular resolution of MAIKo were evaluated with an alpha source and a $^{4}$He beam at 56 MeV. The TPC was stably operated up to 1000-kcps beam intensity. A tracking algorithm using the Hough transform method has been developed to analyze scattering events. An angular resolution of 1.3$^{\circ}$ was achieved for scattered $^{4}$He particles., Comment: 13 pages, 17 figures

A new $^{11}$Be($d,p$)$^{12}$Be transfer reaction experiment was carried out in inverse kinematics at 26.9$A$ MeV, with special efforts devoted to the determination of the deuteron target thickness and of the required optical potentials from the present elastic scattering data. In addition, a direct measurement of the cross sections for the 0$_2^+$ state was realized by applying an isomer-tagging technique. The s-wave spectroscopic factors of 0.20(0.04) and 0.41(0.11) were extracted for the 0$_1^+$ and 0$_2^+$ states, respectively, in $^{12}$Be. Using the ratio of these spectroscopic factors, together with the previously reported results for the p-wave components, the single-particle component intensities in the bound 0$^+$ states of $^{12}$Be were deduced, allowing a direct comparison with the theoretical predictions. It is evidenced that the ground-state configuration of $^{12}$Be is dominated by the d-wave intruder, exhibiting a dramatic evolution of the intruding mechanism from $^{11}$Be to $^{12}$Be, with a persistence of the $N = 8$ magic number broken.

We use Fourier space polarimetry to study the incident angle- and polarization-dependent rotation angle and ellipticity of different diffraction orders emerging from a two-dimensional periodic Au array. The array has square lattice and circular nanoholes and thus is achiral. We find no polarization conversion occurs if the diffraction orders lie in the incident plane. However, for the orders that are diffracted away from the incident plane, their rotation angle and ellipticity vary considerably with incident angle and polarization. In particular, dramatic changes in rotation angle and ellipticity are observed when Bloch-like surface plasmon polaritons (SPPs) are excited. The experimental results are consistent with the finite-difference time-domain simulations. The transverse spin carried by the SPPs and a discrete dipole model are used complementarily to elucidate such angular and polarization dependences.

The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called `magic numbers' of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped explain the nuclear magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number 6 in 13-20C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics., Comment: 7 pages, 5 figures

A new type of neutron detector, named Stack Structure Solid organic Scintillator (S$^4$), consisting of multi-layer plastic scintillators with capability to suppress low-energy $\gamma$ rays under high-counting rate has been constructed and tested. To achieve $\it{n}$-$\gamma$ discrimination, we exploit the difference in the ranges of the secondary charged particles produced by the interactions of neutrons and $\gamma$ rays in the scintillator material. The thickness of a plastic scintillator layer was determined based on the results of Monte Carlo simulations using the Geant4 toolkit. With layer thicknesses of 5 mm, we have achieved a good separation between neutrons and $\gamma$ rays at 5 MeV$_{\rm ee}$ threshold setting. We have also determined the detection efficiencies using monoenergetic neutrons at two energies produced by the $\it{d}$+$\it{d}\to\it{n}$+$^{3}$He reaction. The results agree well with the Geant4 simulations implementing the Li$\grave{\rm e}$ge Intranuclear Cascade hadronic model (INCL++) and the high-precision model of low-energy neutron interactions (NeutronHP)., Comment: 32 pages, 13 figures and 1 table

The $\nu0h_{9/2}$ and $\nu0i_{13/2}$ strength at $^{137}$Xe, a single neutron outside the $N=82$ shell closure, has been determined using the $^{136}$Xe($\alpha$,$^3$He)$^{137}$Xe reaction carried out at 100 MeV. We confirm the recent observation of the second 13/2$^+$ state and reassess previous data on the 9/2$^-$ states, obtaining spectroscopic factors. These new data provide additional constraints on predictions of the same single-neutron excitations at $^{133}$Sn., Comment: 10 pages, 9 figures, 4 tables

Excitation-energy spectra of $^{11}$C nuclei near the $\eta^\prime$-meson production threshold have been measured by missing-mass spectroscopy using the $^{12}$C($p$,$d$) reaction. A carbon target has been irradiated with a 2.5 GeV proton beam supplied by the synchrotron SIS-18 at GSI to produce $\eta^\prime$ meson bound states in $^{11}$C nuclei. Deuterons emitted at $0^\circ$ in the reaction have been momentum-analyzed by the fragment separator (FRS) used as a high-resolution spectrometer. No distinct structure due to the formation of $\eta^\prime$-mesic states is observed although a high statistical sensitivity is achieved in the experimental spectra. Upper limits on the formation cross sections of $\eta^\prime$-mesic states are determined, and thereby a constraint imposed on the $\eta^\prime$-nucleus interaction is discussed., Comment: 13 pages, 14 figures, accepted for publication in Physical Review C

Excitation spectra of $^{11}$C were measured in the $^{12}$C$(p,d)$ reaction near the $\eta'$ emission threshold. A proton beam extracted from the synchrotron SIS-18 at GSI with an incident energy of 2.5 GeV impinged on a carbon target. The momenta of deuterons emitted at 0 degrees were precisely measured with the fragment separator FRS operated as a spectrometer. In contrast to theoretical predictions on the possible existence of deeply bound $\eta'$ mesic states in carbon nuclei, no distinct structures were observed associated with the formation of bound states. The spectra were analyzed to set stringent constraints on the formation cross section and on the hitherto barely-known $\eta'$-nucleus interaction., Comment: 6 pages, 4 figures

Proton radii of $^{12-19}$C densities derived from first accurate charge changing cross section measurements at 900$A$ MeV with a carbon target are reported. A thick neutron surface evolves from $\sim$ 0.5 fm in $^{15}$C to $\sim$ 1 fm in $^{19}$C. The halo radius in $^{19}$C is found to be 6.4$\pm$0.7 fm as large as $^{11}$Li. Ab initio calculations based on chiral nucleon-nucleon and three-nucleon forces reproduce well the radii., Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Lett

We have studied the dependence of the rotation angle and ellipticity on the sample orientation and incident polarization from metallic nanohole arrays. The arrays have four-fold symmetry and thus do not possess any intrinsic chirality. We elucidate the role of surface plasmon polaritons (SPPs) in determining the extrinsic chirality and we verify the results by using finite-difference time-domain simulation. Our results have indicated the outgoing reflection arises from the interference between the nonresonant background, which preserves the input polarization, and the SPP radiation damping, which is linearly polarized but carries a different polarization defined by the vectorial field of SPPs. More importantly, the interference manifests various polarization states ranging from linear to elliptical across the SPP resonance. We analytically formulate the outgoing waves based on temporal coupled mode theory (CMT) and the results agree well with the experiment and simulation. From CMT, we find the polarization conversion depends on the interplay between the absorption and radiative decay rates of SPPs and the sample orientation.

We have measured for the first time the charge-changing cross sections ($\sigma_{\text{CC}}$) of $^{12-16}$C on a $^{12}$C target at energies below $100A$ MeV. To analyze these low-energy data, we have developed a finite-range Glauber model with a global parameter set within the optical-limit approximation which is applicable to reaction cross section ($\sigma_{\text{R}}$) and $\sigma_{\text{CC}}$ measurements at incident energies from 10$A$ to $2100A$ MeV. Adopting the proton-density distribution of $^{12}$C known from the electron-scattering data, as well as the bare total nucleon-nucleon cross sections, and the real-to-imaginary-part ratios of the forward proton-proton elastic scattering amplitude available in the literatures, we determine the energy-dependent slope parameter $\beta_{\rm pn}$ of the proton-neutron elastic differential cross section so as to reproduce the existing $\sigma_{\text{R}}$ and interaction-cross-section data for $^{12}$C+$^{12}$C over a wide range of incident energies. The Glauber model thus formulated is applied to calculate the $\sigma_{\text{\tiny R}}$'s of $^{12}$C on a $^9$Be and $^{27}$Al targets at various incident energies. Our calculations show excellent agreement with the experimental data. Applying our model to the $\sigma_{\text{\tiny R}}$ and $\sigma_{\text{\tiny CC}}$ for the "neutron-skin" $^{16}$C nucleus, we reconfirm the importance of measurements at incident energies below $100A$ MeV. The proton root-mean-square radii of $^{12-16}$C are extracted using the measured $\sigma_{\text{CC}}$'s and the existing $\sigma_{\text{R}}$ data. The results for $^{12-14}$C are consistent with the values from the electron scatterings, demonstrating the feasibility, usefulness of the $\sigma_{\text{CC}}$ measurement and the present Glauber model., Comment: 8 pages, 4 figures