Many neutron star properties, such as the proton fraction, reflect the symmetry energy contributions to the equation of state that dominate when neutron and proton densities differ strongly. To ...constrain these contributions at suprasaturation densities, we measure the spectra of charged pions produced by colliding rare isotope tin (Sn) beams with isotopically enriched Sn targets. Using ratios of the charged pion spectra measured at high transverse momenta, we deduce the slope of the symmetry energy to be 42<L<117 MeV. This value is slightly lower but consistent with the L values deduced from a recent measurement of the neutron skin thickness of ^{208}Pb.
Deformation mechanisms in equiaxed, partially solid Al–15
wt.% Cu are studied in situ by coupling shear-cell experiments with synchrotron X-ray radiography. Direct evidence is presented for granular ...deformation mechanisms in both globular and equiaxed-dendritic samples at solid fractions shortly after crystal impingement. It is demonstrated that dilatancy, arching and jamming occur at the crystal scale, and that these can cause stick–slip flow due to periodic dilation and compaction at low displacement rate. Granular deformation is found to be similar in globular and equiaxed-dendritic samples if length is scaled by the crystal size and packing is considered to occur among crystal envelopes. Rheological differences between the morphologies are discussed in terms of the competition between crystal rearrangement and crystal deformation.
The dipole polarizability of stable even-mass tin isotopes 112,114,116,118,120,124Sn was extracted from inelastic proton scattering experiments at 295MeV 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.
Properties of the nuclear equation of state (EoS) can be probed by measuring the dynamical properties of nucleus-nucleus collisions. In this study, we present the directed flow (v1), elliptic flow ...(v2) and stopping (VarXZ) measured in fixed target Sn + Sn collisions at ▪ with the SπRIT Time Projection Chamber. We perform Bayesian analyses in which EoS parameters are varied simultaneously within the Improved Quantum Molecular Dynamics-Skyrme (ImQMD-Sky) transport code to obtain a multivariate correlated constraint. The varied parameters include symmetry energy, S0, and slope of the symmetry energy, L, at saturation density, isoscalar effective mass, ms⁎/mN, isovector effective mass, mv⁎/mN and the in-medium cross-section enhancement factor η. We find that the flow and VarXZ observables are sensitive to the splitting of proton and neutron effective masses and the in-medium cross-section. Comparisons of ImQMD-Sky predictions to the SπRIT data suggest a narrow range of preferred values for ms⁎/mN, mv⁎/mN and η.
The rapidity distributions of hydrogen isotopes emitted from central collisions of neutron-rich 132Sn+124Sn and neutron-deficient 108Sn+112Sn systems at 270 MeV/nucleon were investigated at ...RIKEN-RIBF. The data are compared with antisymmetrized molecular dynamics (AMD) calculations and the rapidity distributions can be reproduced after adjusting the in-medium nucleon-nucleon cross sections. The double ratios between the two reaction systems taken for the relative yields of deuteron to proton (d/p) and triton to proton (t/p) are further examined in the midrapidity domain, where the adjustments in the AMD calculations do not affect much on them. The d/p and t/p double ratios at midrapidity agree well with the ratio of the system neutron numbers and its squared value, respectively, and the rapidity dependence of these double ratios is consistent with a picture of partial mixing of colliding nuclei. By comparing with the AMD model which shows a strong symmetry energy dependence of the t/p double ratio, the experimental result in the midrapidity domain favors the calculation with a symmetry-energy slope parameter around L=46 MeV rather than L=108 MeV.
Unbound states in C17 were investigated via one-neutron removal from a C18 beam at an energy of 245 MeV/nucleon on a carbon target. The energy spectrum of C17, above the single-neutron decay ...threshold, was reconstructed using invariant mass spectroscopy from the measured momenta of the C16 fragment and neutron, and was found to exhibit resonances at Er=0.52(2), 0.77(2), 1.36(1), 1.91(1), 2.22(3) and 3.20(1) MeV. The resonance at Er=0.77(2) MeV Ex=1.51(3) MeV was provisionally assigned as the second 5/2+ state. The two resonances at Er=1.91(1) and 3.20(1) MeV Ex=2.65(2) and 3.94(2) MeV were identified, through comparison of the energies, cross sections and momentum distributions with shell-model and eikonal reaction calculations, as p-shell hole states with spin-parities 1/21− and 3/21−, respectively. A detailed comparison was made with the results obtained using a range of shell-model interactions. The YSOX shell-model Hamiltonian, the cross-shell part of which is based on the monopole-based universal interaction, was found to provide a very good description of the present results and those for the neighbouring odd-A carbon isotopes – in particular for the negative parity cross-shell states.
Imidazole peptides possess multiple functions, including antioxidant effects, although their biological activities are largely unclear. Their production in humans and animals suggests their ...physiological roles and validates their safety for pharmaceutical or supplemental use. This study investigated the in vitro anti-anaphylactic potential of two histidine-containing dipeptides, carnosine and anserine in mast cells and basophils. Carnosine and anserine reduced mast cell degranulation elicited by anti-ovalbumin monoclonal IgE and ovalbumin or ionomycin in rat basophilic leukemia RBL2H3 cells without affecting cell viability. In contrast, interleukin-4 production following stimulation was enhanced in the presence of carnosine. Carnosine and anserine strongly inhibited Akt phosphorylation and moderately inhibited ERK phosphorylation. However, these peptides enhanced the increase in phosphorylated JNK levels upon IgE stimulation. The phosphorylation levels of p38 were not affected by carnosine or anserine. To determine the effect of carnosine on basophils, we established a method for detecting IgE-dependent activation in primary cultured mouse splenic basophils via CD63 expression for the first time. Carnosine treatment significantly reduced the increase in CD63 surface expression, a marker of degranulation, in mouse splenic basophils stimulated with anti-IgE. Flow cytometory analysis revealed that mean fluorescence intensities for non-stimulated, anti-IgE-stimulated, and carnosine-pre-treated/anti-IgE-stimulated basophils were 3853 ± 320, 5548 ± 282, and 3853 ± 203, respectively. The findings indicate carnosine and anserine suppress mast cell and basophil IgE-dependent degranulation. The proposed mechanism of the inhibitory effect is the suppression of the activation of phosphoinositide 3-kinase–Akt. Carnosine and anserine may exert anti-anaphylactic effects under physiological and pathological conditions and serve as safe potential drug candidates.
Neutron-rich $^{88,90,92,94}$ Se isotopes were studied via in-beam $\gamma$-ray spectroscopy after nucleon removal reactions at intermediate energies at the Radioactive Isotope Beam Factory. Based on ...gamma-gamma coincidence analysis, low-lying excitation level schemes are proposed for these nuclei, including the 2$_1^+$, 4$_1^+$ states and 2$_2^+$ states at remarkably low energies. The low-lying 2$_2^+$ states, along with other features, indicate triaxiality in these nuclei. The experimental results are in good overall agreement with self-consistent beyond-mean-field calculations based on the Gogny D1S interaction, which suggests both triaxial degree of freedom and shape coexistence playing important roles in the description of intrinsic deformations in neutron-rich Se isotopes.
We have implemented the Generic Electronics for Time Projection Chamber (GET) in a SAMURAI Pion Reconstruction and Ion-Tracker (SπRIT) readout system for heavy radioactive ion collision experiments ...at RIKEN-RIBF. The SπRIT experiment is designed for heavy ion collision experiments with radioactive ion beams, where a Time Projection Chamber (TPC) with 12096 pixelized readout pads is employed as the main device. Since the TPC is located on the beam line, the readout electronics must handle small signals from pions as well as very large signals from beam or large fragment particles. Operation of the GET electronics during experiment functioned well using 270 time-bucket readout with 25 MHz sampling at an event Data acquisition (DAQ) rate of 60 Hz. Using the slope information of acquired signals it is possible to extend the dynamic range of dE/dx information compared to using the peak height information. However, huge signals arising from energetic δ-rays produced by un-interacted projectiles induce dead channels, which can be recovered after 70 μs on average.
PDF
