Low-lying state investigations of odd-A Mn isotopes around N=28

Based on the systematic studies for low-lying states of the odd-A^49-57Mn isotopes, the groundstates inversion and the rotational properties of a ground-state-based sequence are revealed and discussed. The energy levels of low-lying states and electromagnetic moments in odd-A^49-57Mn isotopes have been well reproduced in shell-model calculations, and the above phenomena could be understood with obviously different occupation numbers in proton orbitals such as πf_7/2...     

Low-lying states of 109Sn from the 106Cd(α, nγ) reaction

Measurements of γ-ray, γγ-coincidence and internal conversion electron spectra from the ¹⁰⁶Cd(α, nγ)¹⁰⁹Sn reaction were carried out at 15–20 MeV α-particle bombarding energies with Ge(HP) γ-ray and superconducting magnetic lens plus Si(Li) electron spectrometers. The energies, relative intensities, internal conversion coefficients and coincidence relations of the ¹⁰⁹Sn transitions were determined, and a more complete, consistent level scheme has been deduced. Spin and parity values have been determined from the internal conversion coefficients, the bombarding-energy dependence of the side-feeding intensities of the states and the available γ-ray angular distribution data. The level scheme was interpreted in the framework of the quasi-particle shell model.     

Excitation of 1+ AND 2− states in the neon isotopes

High resolution inelastic proton scattering is used to study the excitation of 1⁺ states in ²⁰Ne and ²²Ne. By comparing these results with those from gamma-ray fluorescence measurements, the strong role of the orbital contribution in the electromagnetic transitions, predicted by the theory, is confirmed. Shell model predictions of the 1⁺ strength are compared to the measured strength in ²⁰Ne and ²²Ne. The (p, p′) excitation of 2⁻ states in ²⁰Ne is compared to (π⁻, γ) and (e, e′) results.     

Formation of Light p-shell Ξ − Hypernucleus Via (K −, K +) Reaction

We have calculated ⁷Li(K ^?, K ⁺) reaction spectrum at ${p_{K^-} = 1.65}$ GeV/c and ${\theta_{K}^{+} = 0^\circ}$ within the framework of distorted wave impulse approximation (DWIA) using the ${[\Xi^-{-}^6{\rm He}(0^+)]-[\Xi^-{-}^6{\rm He}^*(2^+)]}$ coupled-channel Green’s function approach, and examined whether the peak corresponding to the Ξ ^? hypernuclear states can be visible in the reaction spectrum, by employing various Ξ ^??⁶He effective potentials.     

Dimers based on the α + α potential and chain states of carbon isotopes

Using the well established binding energies of one and two valence neutrons in the two-center α+α system (forming the states in ⁹Be and ¹⁰Be*) the structure of these nuclear dimers and their rotational bands including those with more than 2 nucleons are discussed using published transfer reaction data for Be and Boron isotopes. Based on the 0 ₂ ⁺ state in ¹²C which is supposed to be an 3α particle chain at an excitation energy of 7.65 MeV and using the binding energy of these valence neutrons in ⁹Be and ¹⁰Be*, chain states in the system ¹²C* + x neutrons are constructed. The energy position of the lowest chain states are estimated and ways for their population in reactions on ⁹Be and using radioactive beams are proposed. It is expected that these states are metastable and could have appreciable branches for γ-decay. Further extrapolations to longer chain states (polymers) in neutron rich light isotopes are made.     

Bayesian inference of the resonance content of p(γ,K+)Λ

A bayesian analysis of the world's p(γ,K^+)Λ data is presented. From the proposed selection of 11 resonances, we find that the following nucleon resonances have the highest probability of contributing to the reaction: S11(1535), S11(1650), F15(1680), P13(1720), D13(1900), P13(1900), P11(1900), and F15(2000). We adopt a Regge-plus-resonance framework featuring consistent couplings for nucleon resonances up to spin J=5/2. We evaluate all possible combinations of 11 candidate resonances. The best model is selected from the 2048 model variants by calculating the bayesian evidence values against the world's p(γ,K+)Λ data.     

Exclusive electroproduction of K+Λ and K+Σ0 final states at Q2 = 0.030–0.055 (GeV/c)2

Cross-section measurements of the exclusive p(e, e??K ⁺)??, ?? ⁰electroproduction reactions have been performed at the Mainz Microtron MAMI in the A1 spectrometer facility using for the first time the KAOS spectrometer for kaon detection. These processes were studied in a kinematical region not covered by any previous experiment. The nucleon was probed in its third-resonance region with virtual photons of low four-momenta, Q ² = 0.030?C0.055 (GeV/c)². The MAMI data indicate a smooth transition in Q² from photoproduction to electroproduction cross-sections. Comparison with predictions of effective Lagrangian models based on the isobar approach reveal that strong longitudinal couplings of the virtual photon to the N^* resonances can be excluded from these models. Modern isobar and Regge-plus-resonance models are in agreement with the data.     

零温物态方程输入参数B_(0K)、B′_(0K)和ρ_(0K)的确定

在对Grüneisen系数高温高压下演化特性不作任何假设的前提下,建立了一种不依赖于等温物态方程具体形式,通过Hugoniot实验数据直接确定0K零压等温体积模量B0K及其对压力的一阶导数B′0K和初始密度ρ0K等0K物态方程输入参数的方法。通过与实验和理论数据的分析和比较,表明用这一方法确定的B0K和B′0K不仅合理,而且具有很高的精度,特别是B′0K的精度,要优于目前传统超声实验的测量精度。此外,这一方法所确定的ρ0K不仅在Gr櫣neisen物态方程的框架内与相应的室温零压特性参数相适配,而且与低温热膨胀实验数据所确定的近0K初始密度ρ0E非常吻合。     

Study of Light Hypernuclei by the (e,e′K +) Reaction

We have been performing Λ hypernuclear spectroscopic experiments by the (e,e′K ⁺) reaction since 2000 at Thomas Jefferson National Accelerator Facility (JLab). The (e,e′K ⁺) experiment can achieve a few 100 keV (FWHM) energy resolution compared to a few MeV (FWHM) by the (K ^?, π ^?) and (π ⁺, K ⁺) experiments. Therefore, more precise Λ hypernuclear structures can be investigated by the (e,e′K ⁺) experiment. ${^{7}_{\Lambda}{\rm He}}$ , ${^{9}_{\Lambda}{\rm Li}}$ , ${^{10}_{\Lambda}{\rm Be}}$ , ${^{12}_{\Lambda}{\rm B}}$ , ${^{28}_{\Lambda}{\rm Al}}$ , and ${^{52}_{\Lambda}{\rm V}}$ were measured in the experiment at JLab Hall-C. In addition, ${^{9}_{\Lambda}{\rm Li}}$ , ${^{12}_{\Lambda}{\rm B}}$ , and ${^{16}_{\Lambda}{\rm N}}$ were measured in the experiment at JLab Hall-A.     

Production of Ξ−-Hypernuclei via the (K −, K +) Reaction in a Quark-Meson Coupling Model

We study the production of Ξ^?-hypernuclei, ${^{12}{_{\Xi^-}}}$ Be and ${^{28}{_{\Xi^-}}}$ Mg, via the (K ^?, K ⁺) reaction within a covariant effective Lagrangian model, employing the bound Ξ^? and proton spinors calculated by the latest quark-meson coupling model. The present treatment yields the 0° differential cross sections for the formation of simple s-state Ξ^? particle-hole states peak at a beam momentum around 1.0 GeV/c with a value in excess of 1 μb.     

Study of Neutron-Rich Hypernuclei by the (π −, K +) Reaction at J-PARC

We are planning to perform an experiment at J-PARC and produce new neutron-rich Λ hypernuclei by using the (π ^?, K ⁺) reaction (J-PARC E10). As the first step, we are planning to produce ${^6_{\Lambda}{\rm H}}$ hypernuclei with a ⁶Li target. To conduct this experiment, we are developing new detectors, those are scintillating fiber tracker, and silicon strip detector, for high rate operation to aim at increasing beam intensity up to 10⁷/spill. As a result of beam test in Jun 2012, we are going to use high-rate beam at least 10⁷/spill.     

Spontaneous dissociation of m≠0 positronium states in strong magnetic fields

Even for an infinitesimally slow motion in a direction transverse to a homogeneous magnetic field, any non-axially symmetric state of positronium becomes unbound beyond a critical field depending on its quantum numbers. All m≠0 bound states disappear beyond 5×10⁴T.     

Observation of B(s)(0) → J/ψf(2)'(1525) in J/ψK+ K- final states

The decay B(s)(0) → J/ψK+ K- is investigated using 0.16 fb(-1) of data collected with the LHCb detector using 7 TeV pp collisions. Although the J/ψ? channel is well known, final states at higher K+ K- masses have not previously been studied. In the K+ K- mass spectrum we observe a significant signal in the f(2)'(1525) region as well as a nonresonant component. After subtracting the nonresonant component, we find B(B(s)(0) → J/ψf(2)'(1525))/B(B(s)(0) → J/ψ?) = (26.4 ± 2.7 ± 2.4)%.