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Using the B$\rho$-defined isochronous mass spectrometry technique, we report the first determination of the $^{23}$Si, $^{26}$P, $^{27}$S, and $^{31}$Ar masses and improve the precision of the $^{28}$S mass by a factor of 11. Our measurements confirm that these isotopes are bound and fix the location of the proton dripline in P, S, and Ar. We find that the mirror energy differences of the mirror-nuclei pairs $^{26}$P-$^{26}$Na, $^{27}$P-$^{27}$Mg, $^{27}$S-$^{27}$Na, $^{28}$S-$^{28}$Mg, and $^{31}$Ar-$^{31}$Al deviate significantly from the values predicted assuming mirror symmetry. In addition, we observe similar anomalies in the excited states, but not in the ground states, of the mirror-nuclei pairs $^{22}$Al-$^{22}$F and $^{23}$Al-$^{23}$Ne. Using $ab~ initio$ VS-IMSRG and mean field calculations, we show that such a mirror-symmetry breaking phenomeon can be explained by the extended charge distributions of weakly-bound, proton-rich nuclei. When observed, this phenomenon serves as a unique signature that can be valuable for identifying proton-halo candidates.

A coherent perfect absorber is capable of completely absorbing input waves. However, the coherent perfect absorption severely depends on the superposition of the input waves, and the perfect absorption is sensitive to the disorder of the absorber. Thus, a robust incoherent perfect absorption, being insensitive to the superposition of input waves and the system disorder, is desirable for practical applications. Here, we demonstrate that the linearly independent destructive interference at the port connections removes the constraint on the coherent input. We propose an approach using the interplay between the loss and localization to form the incoherent perfect absorption. The resonant incidence from either port is completely absorbed. Furthermore, we utilize the lattice configuration supporting the flat band to demonstrate the disorder-immune incoherent perfect absorption. Our findings provide insight into the fundamentals and applications for the perfect absorption of light, microwaves, sound, mechanical waves, and beyond., Comment: 8 pages, 5 figures

We predict novel topological phases with broken time-reversal symmetry supporting the coexistence of opposite chiral edge states, which are fundamentally different from the photonic spin-Hall, valley-Hall, and higher-order topological phases. We find a fine-grained categorization of Chern insulators, their band topologies characterized by identical Chern number are completely different. Furthermore, we prove that different topologies cause zeros in their Bloch wavefunction overlaps, which imprint the band gap closing and appear at the degenerate points of topological phase transition. The Bloch wavefunction overlaps predict the reflection and refraction at a topological time boundary, and the overlap zeros ensure the existence of vanishing revival amplitude at critical times even though different topologies before and after the time boundary have identical Chern number. Our findings create new opportunities for topological metamaterials, uncover the topological feature hidden in the time boundary effect as a probe of topology, and open a venue for the exploration of the rich physics originating from the long-range couplings., Comment: 8 pages, 5 figures

The ground-state mass excess of the $T_{z}=-2$ drip-line nucleus $^{22}$Al is measured for the first time to be $18103(10)$ keV using the newly-developed B$\rho$-defined isochronous mass spectrometry method at the cooler storage ring in Lanzhou. The new mass excess value allowed us to determine the excitation energies of the two low-lying $1^+$ states in $^{22}$Al with significantly reduced uncertainties of 51 keV. Comparing to the analogue states in its mirror nucleus $^{22}$F, the mirror energy differences of the two $1^+$ states in the $^{22}$Al-$^{22}$F mirror pair are determined to be $-625(51)$ keV and $-330(51)$ keV, respectively. The excitation energies and the mirror energy differences are used to test the state-of-the-art \textit{ab initio} valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field theory. The mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of the $\pi s_{1/2}$ orbital., Comment: 8 pages, 5 figures

Symmetry plays a fundamentally important role in physics. In this work, we find a conservation law, $S^{\dagger}(H_{c}^{\dagger})S(H_{c})=I$, which is valid for any non-Hermitian scattering center $H_c$. As a result, the reflections and transmissions of a non-Hermitian system $\left\{ r,t\right\}$ and its Hermitian conjugation system $\left\{ \bar{r},\bar{t}\right\} $ satisfy the conservation law $\bar{r}^{\ast}r+\bar{t}^{\ast}t=1$, instead of the energy conservation law that applies to incoming and outgoing waves in a Hermitian system. Consequently, the pseudo-Hermiticity of a non-Hermitian system ensures an energy-difference conservation. Furthermore, we demonstrate that the energy-difference conservation is respectively valid and invalid in two prototypical anti-$\mathcal{PT}$-symmetric systems, where the energy-difference conservation is protected by the pseudo-Hermiticity. Our findings provide profound insight into the conservation law, the pseudo-Hermiticity, and the anti-$\mathcal{PT}$-symmetry in non-Hermitian systems., Comment: 9 pages, 3 figures

The Aharonov-Bohm (AB) cage enables localized confinement with nondiffractive propagation for arbitrary excitation. In this study, we introduce an anti-parity-time (anti-$\mathcal{PT}$) symmetric imaginary coupling in a generalized Creutz ladder to construct a non-Hermitian AB cage with tunable flat-band energy. We investigate compact localized states and complete localization dynamics, and show that non-Hermiticity affects the localization probability distributions and increases the oscillation period of the AB cage dynamics. Non-Hermitian engineering of the decoupled core of the AB cage is the essential point in our proposal. Our approach is widely applicable to a more general situation and can facilitate the manipulation of localization in physics.

Exceptional point and spectral singularity are two types of singularity that are unique to non-Hermitian systems. Here, we report the high-order spectral singularity as a high-order pole of the scattering matrix for a non-Hermitian scattering system, and the high-order spectral singularity is a unification of the exceptional point and spectral singularity. At the high-order spectral singularity, the scattering coefficients have high-order divergence and the scattering system stimulates high-order lasing. The wave emission intensity is polynomially enhanced, and the order of the growth in the polynomial intensity linearly scales with the order of the spectral singularity. Furthermore, the coherent input controls and alters the order of the spectral singularity. Our findings provide profound insights into the fundamentals and applications of high-order spectral singularities., Comment: 8 pages, 3 figures

A novel technique for broadband high-precision mass measurements of short-lived exotic nuclides is reported. It is based on the isochronous mass spectrometry (IMS) and realizes simultaneous determinations of revolution time and velocity of short-lived stored ions at the cooler storage ring CSRe in Lanzhou. The new technique, named as the $B\rho$-defined IMS or $B\rho$-IMS, boosts the efficiency, sensitivity, and accuracy of mass measurements, and is applied here to measure masses of neutron-deficient $fp$-shell nuclides. In a single accelerator setting, masses of $^{46}$Cr, $^{50}$Fe and $^{54}$Ni are determined with relative uncertainties of (5~-~6)$\times10^{-8}$, thereby improving the input data for testing the unitarity of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. This is the technique of choice for future high-precision measurements of the most rarely produced shortest-lived nuclides., Comment: 8 pages, 4 figures

A novel isochronous mass spectrometry, termed as $B\rho$-defined IMS, is established at the experimental cooler-storage ring CSRe in Lanzhou. Its potential has been studied through high precision mass measurements of $^{58}$Ni projectile fragments. Two time-of-flight detectors were installed in one of the straight sections of CSRe, thus enabling simultaneous measurements of the velocity and the revolution time of each stored short-lived ion. This allows for calculating the magnetic rigidity $B\rho$ and the orbit length $C$ of each ion. The accurate $B\rho(C)$ function has been constructed, which is a universal calibration curve used to deduce the masses of the stored nuclides. The sensitivity to single stored ions, quickness, and background-free characteristics of the method are ideally suited to address nuclides with very short lifetimes and tiniest production yields. In the limiting case of just a single particle, the attained mass resolving power allows one us to determine its mass-over-charge ratio $m/q$ with a remarkable precision of merely $\sim5$ keV. Masses of $T_z = -3/2$ fp-shell nuclides are re-determined with high accuracy, and the validity of the isospin multiplet mass equation is tested up to the heaviest isospin quartet with $A = 55$. The new masses are also used to investigate the mirror symmetry of empirical residual proton-neutron interactions.

The reflectionless coherent light transport in the coupled resonator array is investigated in the presence of intra-resonator intermodal coupling between the clockwise and counterclockwise modes, which plays a constructive role for modulating the light flow rather than inducing the unwanted backscattering. The interplay between the intra-resonator intermodal coupling and the inter-resonator couplings enables the coherent resonant transmission (CRT) of the properly superposed injection constituted by the clockwise and counterclockwise modes. The superposition coefficients of the initial excitation determine the mode chirality of the resonant transmission. Sequentially experiencing the time-reversal process of CRT and the CRT realizes the perfect mode conversion that the mode chirality of the injection wave switches into the opposite after resonant transmission. Our findings on the coherent light transport provide insights for the control and manipulation of light field in the integrated photonics, nanophotonics, chiral optics, and beyond., Comment: 7 pages, 4 figures

Particle beam scattering is a conventional technique for detecting the nature of matter. We studied the scattering problem of a cluster connected to multiple leads. We established the connection between the eigenstate of the topological scattering center and the transmission and reflection amplitudes for the resonant scattering process. We discovered that as an application, this approach enables the detection of the edge state in the band gap for both Hermitian and non-Hermitian systems and the identification of the topology of a system. We investigated two types of Su-Schrieffer-Heeger chains as examples. In addition, we proposed a dynamic scheme through an evanescently coupled-waveguide array to detect the edge state on the basis of measured transmission intensity. Numerical simulation revealed that pattern visibility can be the signature of the edge states., Comment: 10 pages, 7 figures

We investigate the properties of two anti-parity-time (anti-PT )-symmetric four-site scattering centers. The anti-PT -symmetric scattering center may have imaginary couplings, real couplings, and real on-site potentials. The only difference between the two scattering centers is the coupling between two central sites of the scattering center, which plays a crucial role in determining the parity of anti-PT symmetry and significantly affects the scattering properties. For the imaginary coupling, the even-parity anti-PT -symmetric scattering center possesses nonunitary scattering and the difference between the reflection and transmission is unity; for the real coupling, the odd-parity anti-PT -symmetric scattering center possesses unitary scattering and the sum of the reflection and transmission is unity. The coupling-induced different scattering behaviors are verified in the numerical simulations. Our findings reveal that a significant difference in the dynamics can be caused by a slight difference between two similar anti-PT -symmetric non-Hermitian scattering centers., Comment: 8 pages, 6 figures

A new $\alpha$-emitting isotope $^{214}$U, produced by fusion-evaporation reaction $^{182}$W($^{36}$Ar, 4n)$^{214}$U, was identified by employing the gas-filled recoil separator SHANS and recoil-$\alpha$ correlation technique. More precise $\alpha$-decay properties of even-even nuclei $^{216,218}$U were also measured in reactions of $^{40}$Ar, $^{40}$Ca with $^{180, 182, 184}$W targets. By combining the experimental data, improved $\alpha$-decay reduced widths $\delta^2$ for the even-even Po--Pu nuclei in the vicinity of magic neutron number $N=126$ were deduced. Their systematic trends are discussed in terms of $N_{p}N_{n}$ scheme in order to study the influence of proton-neutron interaction on $\alpha$ decay in this region of nuclei. It is strikingly found that the reduced widths of $^{214,216}$U are significantly enhanced by a factor of two as compared with the $N_{p}N_{n}$ systematics for the $84 \leq Z \leq 90$ and $N<126$ even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the $\pi 1f_{7/2}$ and $\nu 1f_{5/2}$ spin-orbit partner orbits, which is supported by a large-scale shell model calculation.

In the isochronous mass spectrometry (IMS) performed at storage rings, masses of short-lived nuclides are determined through precision measurements of their mean revolution times. However, the distribution of revolution times could be seriously deteriorated by instabilities of the ring's magnetic fields. This becomes a significant obstacle for the particle identifications and mass determinations. A data analysis method is described in this paper which is able to largely remove the uncertainties caused by the magnetic field instabilities in the particle identifications and the mean revolution times. We show that this method is very effective for the IMS experiments even when the magnetic fields of a storage ring vary slowly up to a level of $\Delta B/B\sim 10^{-4}$., Comment: 11 pages, 13 figures

By using isochronous mass spectrometry (IMS) at the experimental cooler storage ring CSRe, masses of short-lived $^{44}$Cr, $^{46}$Mn, $^{48}$Fe, $^{50}$Co and $^{52}$Ni were measured for the first time and the precision of the mass of $^{40}$Ti was improved by a factor of about 2. Relative precisions of $\delta m/m=(1-2)\times$10$^{-6}$ have been achieved. Details of the measurements and data analysis are described. The obtained masses are compared with the Atomic-Mass Evaluation 2016 (AME$^{\prime}$16) and with theoretical model predictions. The new mass data enable us to extract the higher order coefficients, $d$ and $e$, of the quartic form of the isobaric multiplet mass equation (IMME) for the $fp$-shell isospin quintets. Unexpectedly large $d$- and $e$-values for $A=44$ quintet are found. By re-visiting the previous experimental data on $\beta$-delayed protons from $^{44}$Cr decay, it is suggested that the observed anomaly could be due to the misidentification of the $T=2$, $J^\pi=0^{+}$ isobaric analog state (IAS) in $^{44}$V.

We report first precision mass measurements of the $1/2^-$ isomeric and $9/2^+$ ground states of $^{101}$In. The determined isomeric excitation energy continues a smooth trend of odd-$A$ indium isotopes up to the immediate vicinity of $N=50$ magic number. This trend can be confirmed by dedicated shell model calculations only if the neutron configuration mixing is considered. We find that the single particle energies are different for different states of the same isotope. The presented configuration-dependent shell evolution, type II shell evolution, in odd-$A$ nuclei is discussed for the first time. Our results will facilitate future studies of single-particle neutron states., Comment: 5 pages, 5 figures, submitted to physical review C, under review

Isochronous mass spectrometry has been applied in the storage ring CSRe to measure the masses of the neutron-rich $^{\operatorname{52-54}}$Sc and $^{54,56}$Ti nuclei. The new mass excess values $ME$($^{52}$Sc) $=$ $-40525(65)$ keV, $ME$($^{53}$Sc) $=$ $-38910(80)$ keV, and $ME$($^{54}$Sc) $=$ $-34485(360)$ keV, deviate from the Atomic Mass Evaluation 2012 by 2.3$\sigma$, 2.8$\sigma$, and 1.7$\sigma$, respectively. These large deviations significantly change the systematics of the two-neutron separation energies of scandium isotopes. The empirical shell gap extracted from our new experimental results shows a significant subshell closure at $N = 32$ in scandium, with a similar magnitude as in calcium. Moreover, we present $ab$ $initio$ calculations using the valence-space in-medium similarity renormalization group based on two- and three-nucleon interactions from chiral effective field theory. The theoretical results confirm the existence of a substantial $N = 32$ shell gap in Sc and Ca with a decreasing trend towards lighter isotones, thus providing a consistent picture of the evolution of the $N = 32$ magic number from the $pf$ into the $sd$ shell., Comment: 6 pages, 5figures, accepted by Physical Review C

Isochronous Mass Spectrometry (IMS) in heavy-ion storage rings is an excellent experimental method for precision mass measurements of exotic nuclei. In the IMS, the storage ring is tuned in a special isochronous ion-optical mode. Thus, the mass-over-charge ratios of the stored ions are directly reflected by their respective revolution times in first order. However, the inevitable momentum spread of secondary ions increases the peak widths in the measured spectra and consequently limits the achieved mass precision. In order to achieve a higher mass resolving power, the ring aperture was reduced to 60 mm by applying a mechanical slit system at the dispersive straight section. The momentum acceptance was reduced as well as better isochronous conditions were achieved. The results showed a significant improvement of the mass resolving power reaching $5.2 \times 10^{5}$, though at the cost of about 40\% ion loss., Comment: 6 pages, 6 figures, proceeding of EMIS2018

Fine structure in the $\alpha$ decay of $^{223}$U was observed in the fusion-evaporation reaction $^{187}$Re($^{40}$Ar, p3n) by using fast digital pulse processing technique. Two $\alpha$-decay branches of $^{223}$U feeding the ground state and 244 keV excited state of $^{219}$Th were identified by establishing the decay chain $^{223}$U $\xrightarrow{\alpha_{1}}$ $^{219}$Th $\xrightarrow{\alpha_{2}}$ $^{215}$Ra $\xrightarrow{\alpha_{3}}$ $^{211}$Rn. The $\alpha$-particle energy for the ground-state to ground-state transition of $^{223}$U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62$^{+14}_{-10}$ $\mu$s. Evolution of nuclear structure for $N$ = 131 even-$Z$ isotones from Po to U was discussed in the frameworks of nuclear mass and reduced $\alpha$-decay width, a weakening octupole deformation in the ground state of $^{223}$U relative to its lighter isotones $^{219}$Ra and $^{221}$Th was suggested., Comment: 6 pages, 6 figures

In the last two and a half decades ion storage rings have proven to be powerful tools for precision experiments with unstable nuclides in realm of nuclear structure and astrophysics. There are presently three storage ring facilities in the world at which experiments with stored radioactive ions are possible. These are the ESR in GSI, Darmstadt/Germany, the CSRe in IMP, Lanzhou/China, and the R3 storage ring in RIKEN, Saitama/Japan. In this work, an introduction to the facilities is given. Selected characteristic experimental results and their impact in nuclear physics and astrophysics are presented. Planned technical developments and the envisioned future experiments are outlined., Comment: Focus issue to celebrate the 40 year anniversary of the 1975 Nobel Prize to Aage Niels Bohr, Ben Roy Mottelson and Leo James Rainwater

Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction products. This approach is complementary to conventional gamma-ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin I = 19/2 states in the mirror nuclei 53Fe and 53Co are measured to study angular momentum population following the projectile fragmentation of 78Kr at energies of 480A MeV on a beryllium target. The 19/2 state isomeric ratios of 53Fe produced from different projectiles in the literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to ABRABLA07 model calculations. The isomeric ratios of 53Fe produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss., Comment: 6 pages, 5 figures

Atomic masses of seven $T_z=-1$, $fp$-shell nuclei from $^{44}$V to $^{56}$Cu and two low-lying isomers, $^{44m}$V ($J^\pi=6^+$) and $^{52m}$Co ($J^\pi=2^+$), have been measured with relative precisions of $1-4\times 10^{-7}$ with Isochronous Mass Spectrometry (IMS) at CSRe. The masses of $^{56}$Cu, $^{52g,52m}$Co, and $^{44m}$V were measured for the first time in this experiment. The Mass Excesses ($ME^{\prime}$s) of $^{44}$V, $^{48}$Mn, $^{50}$Fe, and $^{54}$Ni are determined with an order of magnitude improved precision compared to the literature values. $^{52g,52m}$Co and $^{56}$Cu are found to be $370$~keV and $400$~keV more bound, respectively, while $^{44g,44m}$V are $\sim 300$~keV less bound than the extrapolations in the Atomic-Mass Evaluation 2012 (AME$^{\prime}$12). The masses of the four $T_z=-1/2$ nuclei $^{45}$V, $^{47}$Cr, $^{49}$Mn, and $^{51}$Fe are re-determined to be in agreement, within the experimental errors, with the recent JYFLTRAP measurements or with the previous IMS measurements in CSRe. Details of the measurements and data analysis are described, and the impact of the new $ME$ values on different aspects in nuclear structure are investigated and discussed., Comment: 16 pages, 15 figures

The Isochronous Mass Spectrometry (IMS) is a powerful technique developed in heavy-ion storage rings for measuring masses of very short-lived exotic nuclei. The IMS is based on the isochronous setting of the ring. One of the main parameters of this setting is the transition energy $\gamma_{t}$. %The transition energy $\gamma_{t}$ plays an important role in the isochronous mass spectrometry (IMS). It has been a challenge to determine the $\gamma_{t}$ and especially to monitor the variation of $\gamma_{t}$ during experiments. In this paper we introduce a method to measure the $\gamma_{t}$ online during IMS experiments by using the acquired experimental data. Furthermore, since the storage ring has (in our context) a relatively large momentum acceptance, the variation of the $\gamma_{t}$ across the ring acceptance is a source of systematic uncertainty of measured masses. With the installation of two time-of-flight (TOF) detectors, the velocity of each stored ion and its revolution time are simultaneously available for the analysis. These quantities enabled us to determine the $\gamma_{t}$ as a function of orbital length in the ring. The presented method is especially important for future IMS experiments planned at the new-generation storage ring facilities FAIR in Germany and HIAF in China., Comment: 7 pages

The FOPI Collaboration at the GSI SIS-18 synchrotron measured charged kaons from central and semi-central collisions of Ni+Ni at a beam energy of 1.91A GeV. We present the distribution of the K$^-$\K$^+$ ratio on the energy vs polar angle plane in the nucleon-nucleon center-of-mass frame, with and without subtraction of the contribution of $\phi$(1020) meson decays to the K$^-$ yield. The acceptance of the current experiment is substantially wider compared to the previous measurement of the same colliding system. The ratio of K$^-$ to K$^+$ energy spectra is expected to be sensitive to the in-medium modifications of basic kaon properties like mass. Recent results obtained by the HADES Collaboration at 1.23A and 1.76A GeV indicate that after inclusion of the $\phi$ meson decay contribution to the K$^-$ production no difference between the slopes of the K$^-$ and K$^+$ energy spectra is observed within uncertainties. For our data a linear fit to this ratio obtained after subtraction of the $\phi$ meson contribution still shows a decrease with kinetic energy, although a constant value cannot be rejected. The contribution of $\Lambda(1520) \rightarrow p\text{K}^-$ decays estimated from fitting the thermal model to the experimental yields appears to be another factor of moderate relevance., Comment: 8 pages, 4 figures, 2 tables (1 appendix table)

Isochronous mass spectrometry has been applied in the storage ring CSRe to measure the masses of the $T_z=-3/2$ nuclei $^{27}$P and $^{29}$S. The new mass excess value $ME$($^{29}$S) $=-3094(13)$~keV is 66(52)~keV larger than the result of the previous $^{32}$S($^3$He,$^{6}$He)$^{29}$S reaction measurement in 1973 and a factor of 3.8 more precise. The new result for $^{29}$S, together with those of the $T=3/2$ isobaric analog states (IAS) in $^{29}$P, $^{29}$Si, and $^{29}$Al, fit well into the quadratic form of the Isobaric Multiplet Mass Equation IMME. The mass excess of $^{27}$P has been remeasured to be $ME(^{27}$P$)=-685(42)$ keV. By analyzing the linear and quadratic coefficients of the IMME in the $T_z=-3/2$ $sd$-shell nuclei, it was found that the ratio of the Coulomb radius parameters is $R\approx0.96$ and is nearly the same for all $T=3/2$ isospin multiplets. Such a nearly constant $R$-value, apparently valid for the entire light mass region with $A>9$, can be used to set stringent constraints on the isovector and isotensor components of the isospin non-conserving forces in theoretical calculations., Comment: 7 pages, 4 figures

Lifetime measurements of b -decaying highly charged ions have been performed in the storage ring CSRe by applying the isochronous Schottky mass spectrometry. The fully ionized 49Cr and 53Fe ions were produced in projectile fragmentation of 58Ni primary beam and were stored in the CSRe tuned into the isochronous ion-optical mode. The new resonant Schottky detector was applied to monitor the intensities of stored uncooled 49Cr24+ and 53Fe26+ ions. The extracted half-lives T1/2(49Cr24+) = 44.0(27) min and T1/2(53Fe26+) = 8.47(19) min are in excellent agreement with the literature half-life values corrected for the disabled electron capture branchings. This is an important proof-of-principle step towards realizing the simultaneous mass and lifetime measurements on exotic nuclei at the future storage ring facilities.

Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of $^{82}$Zr and $^{84}$Nb were measured for the first time with an uncertainty of $\sim 10$ keV, and the masses of $^{79}$Y, $^{81}$Zr, and $^{83}$Nb were re-determined with a higher precision. %The latter differ significantly from their literature values. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low $\alpha$ separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr-Nb cycle in the $rp$-process unlikely. The new proton separation energy of $^{83}$Nb was determined to be 490(400)~keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the $p$-nucleus $^{84}$Sr relative to the neutron-deficient molybdenum isotopes in the previous $\nu p$-process simulations.

$^{6}$He+$t$ cluster states of exited $^{9}$Li have been measured by 32.7 MeV/nucleon $^{9}$Li beams bombarding on $^{208}$Pb target. Two resonant states are clearly observed with the excitation energies at 9.8 MeV and 12.6 MeV and spin-parity of 3/2$^{-}$ and 7/2$^{-}$ respectively. These two states are considered to be members of K$^{\pi}$=1/2$^{-}$ band. The spin-parity of them are identified by the method of angular correlation analysis and verified by the continuum discretized coupled channels (CDCC) calculation, which agrees with the prediction of the generator coordinate method (GCM). A monopole matrix element about 4 fm$^{2}$ for the 3/2$^{-}$ state is extracted from the distorted wave Born approximation (DWBA) calculation. These results strongly support the feature of clustering structure of two neutron-rich clusters in the neutron-rich nucleus $^{9}$Li for the first time.

Masses of $^{52g,52m}$Co were measured for the first time with an accuracy of $\sim 10$ keV, an unprecedented precision reached for short-lived nuclei in the isochronous mass spectrometry. Combining our results with the previous $\beta$-$\gamma$ measurements of $^{52}$Ni, the $T=2$, $J^{\pi}=0^+$ isobaric analog state (IAS) in $^{52}$Co was newly assigned, questioning the conventional identification of IASs from the $\beta$-delayed proton emissions. Using our energy of the IAS in $^{52}$Co, the masses of the $T=2$ multiplet fit well into the Isobaric Multiplet Mass Equation. We find that the IAS in $^{52}$Co decays predominantly via $\gamma$ transitions while the proton emission is negligibly small. According to our large-scale shell model calculations, this phenomenon has been interpreted to be due to very low isospin mixing in the IAS., Comment: Accepted for publication in PRL. 5 pages, 2figures

The decay of the proton-rich nucleus $^{22}$Si was studied by a silicon array coupled with germanium clover detectors. Nine charged-particle groups are observed and most of them are recognized as $\beta$-delayed proton emission. A charged-particle group at 5600 keV is identified experimentally as $\beta$-delayed two-proton emission from the isobaric analog state of $^{22}$Al. Another charged-particle emission without any $\beta$ particle at the low energy less than 300 keV is observed. The half-life of $^{22}$Si is determined as 27.5 (18) ms. The experimental results of $\beta$-decay of $^{22}$Si are compared and in nice agreement with shell-model calculations. The mass excess of the ground state of $^{22}$Si deduced from the experimental data shows that three-nucleon (3N) forces with repulsive contributions have significant effects on nuclei near the proton drip line., Comment: 6 pages, 4 figures

Excited states in neutron-rich nuclei located south-east of $^{132}$Sn are investigated by shell-model calculations. A new shell-model Hamiltonian is constructed for the present study. The proton-proton and neutron-neutron interactions of the Hamiltonian are obtained through the existing CD-Bonn $G$ matrix results, while the proton-neutron interaction across two major shells is derived from the monopole based universal interaction plus the M3Y spin-orbit force. The present Hamiltonian can reproduce well the experimental data available in this region, including one-neutron separation energies, level energies and the experimental $B(E2)$ values of isomers in $^{134,136,138}$Sn, $^{130}$Cd, and $^{128}$Pd. New isomers are predicted in this region, $e.g.$ in $^{135}$Sn, $^{131}$Cd, $^{129}$Pd, $^{132,134}$In and $^{130}$Ag, in which almost no excited states are known experimentally yet. In the odd-odd $^{132,134}$In and $^{130}$Ag, the predicted very long $E2$ life-times of the low-lying $5^{-}$ states are discussed, demanding more information on the related proton-neutron interaction. The low-lying states of $^{132}$In are discussed in connection with the recently observed $\gamma$ rays. The predicted $19/2^{-}$ isomer in $^{129}$Pd could decay by both electromagnetic transitions and neutron emission with comparable partial life-times, making it a good candidate for neutron radioactivity, a decay mode which is yet to be discovered., Comment: Accepted for publication in Physics Letters B

We analysed the $\phi$ meson production in central Ni+Ni collisions at the beam kinetic energy of 1.93A GeV with the FOPI spectrometer and found the production probability per event of $[8.6 ~\pm~ 1.6 ~(\text{stat}) \pm 1.5 ~(\text{syst})] \times 10^{-4}$. This new data point allows for the first time to inspect the centrality dependence of the subthreshold $\phi$ meson production in heavy-ion collisions. The rise of $\phi$ meson multiplicity per event with mean number of participants can be parameterized by the power function with exponent $\alpha = 1.8 \pm 0.6$. The ratio of $\phi$ to $\text{K}^-$ production yields seems not to depend within the experimental uncertainties on the collision centrality, and the average of measured values was found to be $0.36 \pm 0.05$., Comment: 9 pages, 5 figures

Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for mass measurements of exotic nuclei with very short half-lives down to several tens of microseconds, using a multicomponent secondary beam separated in-flight without cooling. However, the inevitable momentum spread of secondary ions limits the precision of nuclear masses determined by using IMS. Therefore, the momentum measurement in addition to the revolution period of stored ions is crucial to reduce the influence of the momentum spread on the standard deviation of the revolution period, which would lead to a much improved mass resolving power of IMS. One of the proposals to upgrade IMS is that the velocity of secondary ions could be directly measured by using two time-of-flight (double TOF) detectors installed in a straight section of a storage ring. In this paper, we outline the principle of IMS with double TOF detectors and the method to correct the momentum spread of stored ions., Comment: Accepted by Nuclear Inst. and Methods in Physics Research, B

Thermal conductivity (\kappa) of a distorted spin diamond-chain system, Cu_3(CO_3)_2(OH)_2, is studied at low temperatures down to 0.3 K and in magnetic fields up to 14 T. In zero field, the \kappa(T) curve with heat current along the chain direction has very small magnitudes and shows a pronounced three-peak structure. The magnetic fields along and perpendicular to the chains change the \kappa strongly in a way having good correspondence to the changes of magnetic specific heat in fields. The data analysis based on the Debye model for phononic thermal conductivity indicates that the heat transport is due to phonons and the three-peak structure is caused by two resonant scattering processes by the magnetic excitations. In particular, the spin excitations of the chain subsystem are strongly scattering phonons rather than transporting heat., Comment: 15 pages, 6 figures, accepted for publication in J. Phys.: Condens. Matt

The extent of nucleosynthesis in models of type I X-ray bursts and the associated impact on the energy released in these explosive events are sensitive to nuclear masses and reaction rates around the $^{64}$Ge waiting point. Using the well known mass of $^{64}$Ge, the recently measured $^{65}$As mass, and large-scale shell model calculations, we have determined new thermonuclear rates of the $^{64}$Ge($p$,$\gamma$)$^{65}$As and $^{65}$As($p$,$\gamma$)$^{66}$Se reactions with reliable uncertainties. The new reaction rates differ significantly from previously published rates. Using the new data we analyze the impact of the new rates and the remaining nuclear physics uncertainties on the $^{64}$Ge waiting point in a number of representative one-zone X-ray burst models. We find that in contrast to previous work, when all relevant uncertainties are considered, a strong $^{64}$Ge $rp$-process waiting point cannot be ruled out. The nuclear physics uncertainties strongly affect X-ray burst model predictions of the synthesis of $^{64}$Zn, the synthesis of nuclei beyond $A=64$, energy generation, and burst light curve. We also identify key nuclear uncertainties that need to be addressed to determine the role of the $^{64}$Ge waiting point in X-ray bursts. These include the remaining uncertainty in the $^{65}$As mass, the uncertainty of the $^{66}$Se mass, and the remaining uncertainty in the $^{65}$As($p$,$\gamma$)$^{66}$Se reaction rate, which mainly originates from uncertain resonance energies., Comment: 11 pages, 6 figures, accepted by ApJ

The heat transport of the spin-gapped material (CH_3)_2CHNH_3CuCl_3 (IPA-CuCl_3), a candidate quantum magnet with Bose-Einstein condensation (BEC), is studied at ultra-low temperatures and in high magnetic fields. Due to the presence of the spin gap, the zero-field thermal conductivity (\kappa) is purely phononic and shows a ballistic behavior at T < 1 K. When the gap is closed by magnetic field at H = H_{c1}, where a long-range antiferromanetic (AF) order of Cu^{2+} moments is developed, the magnons contribute significantly to heat transport and exhibit a ballistic T^3 behavior at T < 600 mK. In addition, the low-T \kappa(H) isotherms show sharp peaks at H_{c1}, which indicates a gap re-opening in the AF state (H > H_{c1}) and demonstrates limited applicability of the BEC model to IPA-CuCl_3., Comment: 9 pages, 5 figures, accepted for publication in Phys. Rev. B

Isochronous mass spectrometry (IMS) in storage rings is a successful technique for accurate mass measurements of short-lived nuclides with relative precision of about $10^{-5}-10^{-7}$. Instabilities of the magnetic fields in storage rings are one of the major contributions limiting the achievable mass resolving power, which is directly related to the precision of the obtained mass values. A new data analysis method is proposed allowing one to minimise the effect of such instabilities. The masses of the previously measured at the CSRe $^{41}$Ti, $^{43}$V, $^{47}$Mn, $^{49}$Fe, $^{53}$Ni and $^{55}$Cu nuclides were re-determined with this method. An improvement of the mass precision by a factor of $\sim 1.7$ has been achieved for $^{41}$Ti and $^{43}$V. The method can be applied to any isochronous mass experiment irrespective of the accelerator facility. Furthermore, the method can be used as an on-line tool for checking the isochronous conditions of the storage ring.

Revolution frequency measurements of individual ions in storage rings require sophisticated timing detectors. One of common approaches for such detectors is the detection of secondary electrons released from a thin foil due to penetration of the stored ions. A new method based on the analysis of intensities of secondary electrons was developed which enables determination of the charge of each ion simultaneously with the measurement of its revolution frequency. Although the mass-over-charge ratios of $^{51}$Co$^{27+}$ and $^{34}$Ar$^{18+}$ ions are almost identical, and therefore, the ions can not be resolved in a storage ring, by applying the new method the mass excess of the short-lived $^{51}$Co is determined for the first time to be ME($^{51}$Co)=-27342(48) keV. Shell-model calculations in the $fp$-shell nuclei compared to the new data indicate the need to include isospin-nonconserving forces.

The thermonuclear rate of the $^{42}$Ti($p$,$\gamma$)$^{43}$V reaction has been reevaluated based on a recent precise proton separation energy measurement of $S_p$($^{43}$V)=83$\pm$43 keV. The astrophysical impact of our new rates has been investigated through one-zone postprocessing type I x-ray burst calculations. It shows that the new experimental value of $S_p$ significantly affects the yields of species between A$\approx$40--45. As well, the precision of the recent experimental $S_p$ value constrains these yields to better than a factor of three.

In the last two decades a number of nuclear structure and astrophysics experiments were performed at heavy-ion storage rings employing unique experimental conditions offered by such machines. Furthermore, building on the experience gained at the two facilities presently in operation, several new storage ring projects were launched worldwide. This contribution is intended to provide a brief review of the fast growing field of nuclear structure and astrophysics research at storage rings., Comment: XVIth International Conference on Electro-Magnetic Isotope Separators and Techniques Related to their Applications, December 2--7, 2012 at Matsue, Japan

The performance of a double sided silicon strip detector (DSSSD), used for position and energy detection of heavy ions, is reported. The analysis shows that the incomplete charge collection (ICC) and charge sharing (CS) effects of the DSSSD give rise to a loss of energy resolution, however the position information is recorded without ambiguity. Representations of ICC/CS events in the energy spectra are shown and their origins are confirmed by correlation analysis of the spectra from both junction side and ohmic side of the DSSSD.

The longitudinal Schottky spectra of a radio-frequency (RF) bunched and electron cooled 22Ne10+ ion beam at 70 MeV/u have been studied by a newly installed resonant Schottky pick-up at the experimental cooler storage ring (CSRe), at IMP. For an RF-bunched ion beam, a longitudinal momentum spread of has been reached with less than 107 stored ions. The reduction of momentum spread compared with coasting ion beam was observed from Schottky noise signal of the bunched ion beam. In order to prepare the future laser cooling experiment at the CSRe, the RF-bunching power was modulated at 25th, 50th and 75th harmonic of the revolution frequency, effective bunching amplitudes were extracted from the Schottky spectrum analysis. Applications of Schottky noise for measuring beam lifetime with ultra-low intensity of ion beams are presented, and it is relevant to upcoming experiments on laser cooling of relativistic heavy ion beams and nuclear physics at the CSRe., Comment: to be published in Chinese Physics C

The energy spectra of light charged particles and intermediate mass fragments from 112Sn+112Sn and 124Sn+124Sn collisions at an incident energy of E/A=50 MeV have been measured with a large array of Silicon strip detectors. We used charged particle multiplicities detected in an array with nearly 4-pi coverage to select data from the central collision events. We study isospin observables analogous to ratios of neutron and proton spectra, including double ratios and yield ratios of t/3He and of asymmetries constructed from fragments with Z=3 to Z=8. Using the energy spectra, we can construct these observables as functions of kinetic energy. Most of the fragment asymmetry observables have a large sensitivity to sequential decays.

Spectrum of low-lying five-quark configurations with strangeness quantum number $S=-3$ and negative parity is studied in three kinds of constituent quark models, namely the one gluon exchange, Goldstone Boson exchange, and instanton-induced hyperfine interaction models, respectively. Our numerical results show that the lowest energy states in all the three employed models are lying at $\sim$1800 MeV, about 200 MeV lower than predictions of various quenched three-quark models. In addition, it is very interesting that the state with the lowest energy in one gluon exchange model is with spin 3/2, but 1/2 in the other two models., Comment: Version published in Phys. Rev. C

The storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination (DR) experiments. In order to fulfil the requirement of DR measurements at the main Cooler Storage Ring, a detuning system for the precision control of the relative energy between the ion beam and the electron beam has been installed on the electron cooler device. The test run using 7.0 MeV/u C6+ beam was performed to examine the influence of this system on the performance of the stored ion beam. The Schottky spectra and the ion beam currents were recorded to monitor the beam status. The influence of pulse heights and widths of the detuning voltage on the ion beam was investigated. For the small pulse height, the experimental results from the Schottky spectrum were in good agreement with the theoretical results. The frequency shift in the Schottky spectrum is significantly reduced for the short pulse width. For the large pulse height, an oscillation phenomenon was observed. From the Schottky spectrum, we found the oscillation amplitude is dependent on the pulse width of detuning and the ion beam intensity. The detailed description of the phenomenon and the theoretical model based on the plasma oscillation was discussed in this paper., Comment: contributed to Chinese Physics C

The low-lying energy spectra of five quark systems $uudc\bar{c}$ (I=1/2, S=0) and $udsc\bar{c}$ (I=0, S=-1) are investigated with three kinds of schematic interactions: the chromomagnetic interaction, the flavor-spin dependent interaction and the instanton-induced interaction. In all the three models, the lowest five quark state ($uudc\bar{c}$ or $udsc\bar{c}$) has an orbital angular momentum L=0 and the spin-parity $J^{P}=1/2^{-}$; the mass of the lowest $udsc\bar{c}$ state is heavier than the lowest $uudc\bar{c}$ state.