Feasibility studies of the EXL setup for FAIR using the GSI storage ring ESR

The investigation of light-ion induced direct reactions in inverse kinematics, using stored and cooled radioactive beams, interacting with internal H, He, etc. gas-jet targets, bears a large potential for nuclear structure and astrophysics studies on exotic nuclei. An extended research project EXL has been accepted for the future facility FAIR in Darmstadt, Germany. In order to explore the experimental conditions for measurements planned at FAIR, a first test experiment for proving the feasibility of the EXL concept was performed.     

Strangeness at the international Facility for Antiproton and Ion Research

The project of the international Facility for Antiproton and Ion Research (FAIR), co-located to the GSI facility in Darmstadt, was officially started on November 7, 2007. An investment of about 1 billion euro will permit new physics programs in the areas of low and medium energy antiproton research, heavy ion physics complementary to LHC, as well as in nuclear structure and astrophysics. The facility will comprise about a dozen accelerators and storage rings, which will enable simultaneous operations of up to four different beams.     

Radioactive ion beams at FAIR-NuSTAR

The future FAIR facility will open up an unprecedented range of exotic nuclear beams in the energy interval between 0–1.5 GeV/u produced by the Super-FRS. The envisaged experimental programme with radioactive beams, being prepared within the NuSTAR collaboration, will cover most aspects of contemporary physics within nuclear structure, astrophysics and reactions. An overview of this programme is given, with emphasis on high-energy reactions.     

Direct mass measurements of exotic nuclei at the FRS-ESR facility at GSI

An overview of direct mass measurements of exotic nuclei at the FRS-ESR facility at GSI is given. The nuclides are produced at relativistic energies by projectile fragmentation and fission, separated in-flight at the fragment separator FRS and injected into the storage ring ESR. Mass measurements are performed using Schottky and Isochronous Mass Spectrometry, which both allow for high precision measurements with single-ion sensitivity. Recent experimental developments are summarized, and examples for measurement results are given, including applications in nuclear structure physics and astrophysics, comparisons with mass predictions, and the search for new isotopes and isomers. Further research potential will be available at next-generation fragment-separator-storage-ring facilities such as the Super-FRS-CR-NESR complex at the future FAIR facility.     

Doubly strange hypernuclei at PANDA

The FAIR project aims to investigate several fields of physics: QCD, nuclear structure, astrophysics, atomic physics, plasma physics and their applications. In particular, the high-energy storage ring (HESR) will allow high-precision measurements in the antiproton momentum range from 1.5 to 15?GeV/c. Inside HESR, the PANDA experiment will study the charm and strangeness physics, the form factor in the time-like region and other topics like the crossed-channel Compton scattering. The study of the strangeness will be focused onto the doubly strange systems (hypernuclei and hyperatoms) produced with a new technique starting from the antiproton-nucleus reaction.     

核天体物理实验研究

研究微观世界的核物理与研究宏观世界的天体物理自然融合形成了前沿交叉学科——核天体物理。核天体物理的主要研究目标是应用核物理的知识和规律来阐释宇宙演化进程中化学元素合成及演化过程、时间标度、天体环境和天体场所,来说明恒星中核燃烧产生的能量及其对恒星结构和演化的影响,来认识致密天体的结构和性质。文章阐述了核天体物理研究的意义和现状,介绍了有关基本概念和天体网络模型所需的核物理输入量以及广泛应用的一些实验方法,同时扼要地分析了利用国内大科学装置开展核天体物理研究的可行性。最后对未来我国深地科学与工程实验室的建设前景做了展望。     

我国核天体物理前沿研究进展

核天体物理是研究微观世界的核物理与研究宏观世界的天体物理融合形成的交叉学科,其主要研究目标是:宇宙中各种化学元素核合成的过程、时间、物理环境、天体场所及丰度分布;核反应（包括带电粒子、中子、光子及中微子引起的反应、β衰变及电子俘获）如何控制恒星的演化过程和结局。近十多年来获得的大量实验和理论研究使核天体物理研究进入了一个蓬勃发展的新阶段。文章总结了以兰州重离子加速器、北京串列加速器和国家天文台为基础,结合国际合作,在核天体物理研究领域对直接测量、间接测量、衰变测量、质量测量、理论计算、网络计算、天文观测等关键科学问题进行的研究进展。也展望了核天体物理的关键科学问题,这些关键问题包括:（1）在地面实验室、尤其是地下实验室开展天体物理能区重要热核反应截面的直接测量;（2）高能区带电粒子反应截面向天体物理能区的合理外推;（3）恒星平稳核燃烧阶段和爆发性天体事件中关键核反应截面的间接测量;（4）爆发性天体事件中所涉及的大量远离稳定线核素的质量、衰变特性和共振态性质的研究;（5）建立并不断完善核天体物理数据库,发展网络模拟程序,系统研究元素核合成的天体场所、丰度分布;（6）宇宙中铁以上元素的来源之谜。Nuclear astrophysics is an interdisciplinary research field. It composes of nuclear physics, which studies micro phenomena, and astrophysics which studies macroscopic phenomena in our world. The main research goals of nuclear astrophysics are:(1) how, when and where chemical elements are synthesized and what is their final abundance distribution in the universe; (2) how nuclear processes (reactions induced by charged particles, neutrons, photons and neutrinos, beta decays and electron capture processes) determine the evolution and the ultimate fate of stars. At present, nuclear astrophysics has been developed into a new prosperous stage with a huge number of experimental and theoretical progresses. This paper summarized the current progress of nuclear astrophysics in China, in the subfiels of direct and indirect measurement of key reactions, measurement of mass and decay, as well as the theoretical calculation and network simulation. In present paper, the prospects to solve the key scientific nuclear astrophysics problems are represented. These key problems include (1) direct measurement of important reactions at astrophysical energies in the laboratory on the earth surface and in the underground laboratory; (2)extrapolation of cross sections at higher energies for the reactions induced by charged particles; (3) indirect measurement of key reactions in the hydrostatic and explosive nuclear processes; (4) study of the mass, the properties of decay and resonant states for the nuclides far from the stability line in explosive astrophysical events; (5) establish and improve the database for nuclear astrophysics, and develop network simulation codes, and systematically study astrophysical sites and abundance distribution of nucleosynthesis; (6) origin of the elements heavier than iron in the universe.     

Time-like proton form factor measurement with PANDA

The electromagnetic probe is an excellent tool to investigate the structure of the nucleon. The nearly 4π detector PANDA, will allow to make a precise determination of the electromagnetic form factors of the proton in the time-like region with unprecedented precision. In the one-photon exchange approximation, the center of mass unpolarized differential cross section of the reaction pp → e＋e- is a linear combination of the squared moduli of the electric GE and magnetic GM proton form factors. The precise measurement of the angular distribution over almost full angular range then directly gives these quantities. At present only two experiments have provided the ratio R=｜ GE｜/｜GM｜ but with large statistical uncertainties. It is shown that with strict PID cuts and a kinematic fit, the dominant background, pp→π＋π-, can be supressed to much less than 1% of the signal, without affecting the extraction of the ratio R. PANDA will therefore offer a unique opportunity to measure the ratio with a precision ranging from 〈1% at low q2 up to 30 % for q2 = 14 （GeV/c）2.     

How deep is the antinucleon optical potential at FAIR energies

The key question in the interaction of antinucleons in the nuclear medium concerns the deepness of the antinucleon-nucleus optical potential. In this work we study this task in the framework of the non-linear derivative (NLD) model which describes consistently bulk properties of nuclear matter and Dirac phenomenology of nucleon-nucleus interactions. We apply the NLD model to antinucleon interactions in nuclear matter and find a strong decrease of the vector and scalar self-energies in energy and density and thus a strong suppression of the optical potential at zero momentum and, in particular, at FAIR energies. This is in agreement with available empirical information and, therefore, resolves the issue concerning the incompatibility of G-parity arguments in relativistic mean-field (RMF) models. We conclude the relevance of our results for the future activities at FAIR.     

Proposal for the study of thermophysical properties of high-energy-density matter using current and future heavy-ion accelerator facilities at GSI Darmstadt

The subject of high-energy-density (HED) states in matter is of considerable importance to numerous branches of basic as well as applied physics. Intense heavy-ion beams are an excellent tool to create large samples of HED matter in the laboratory with fairly uniform physical conditions. Gesellschaft für Schwerionenforschung, Darmstadt, is a unique worldwide laboratory that has a heavy-ion synchrotron, SIS18, that delivers intense beams of energetic heavy ions. Construction of a much more powerful synchrotron, SIS100, at the future international facility for antiprotons and ion research (FAIR) at Darmstadt will lead to an increase in beam intensity by 3 orders of magnitude compared to what is currently available. The purpose of this Letter is to investigate with the help of two-dimensional numerical simulations, the potential of the FAIR to carry out research in the field of HED states in matter.     

Steady-state thermonuclear plasma as a source of nuclear-physics data

Measurements of cross sections of nuclear reactions of charged particles in the kiloelectron-volt range present a difficult experimental problem because of their small size. At the same time, the need for accuracy in the determination of such cross sections continues to grow in connection with the active development of such branches of science as controlled thermonuclear fusion, astrophysics, cosmology, and nuclear physics itself. The present communication discusses the motivation for performing experiments in this energy range and the difficulties such experiments involve, and proposes a new experimental approach to measuring the cross sections of such reactions using the steady-state plasmas available in thermonuclear facilities. Zh. Tekh. Fiz. 69, 114–118 (January 1999)     

Theoretical study on neutron distribution of ~(208)Pb by parity-violating electron scattering

The precise determination of neutron distribution has important implications for both nuclear structure and nuclear astrophysics. The purpose of this paper is to study the characteristics of neutron distribution of~(208) Pb by parity-violating electron scattering(PVS). Parity-violating asymmetries of~(208) Pb with different types of neutron skins are systematically calculated and compared with the experimental data of PREx. The results indicate that the PVS experiments are very sensitive to the nuclear neutron distributions. From further PVS measurements, detailed information on nuclear neutron distributions can be extracted.     

重离子核反应与核物质状态方程

核物质状态方程描述核物质结合能、压强、密度和中子—质子数差异等宏观量之间的关系。核物质状态方程不仅仅与核力属性、核结构性质以及重离子核反应的动力学过程紧密相关,还与致密星体如中子星的结构、演化、辐射与并合等天体过程紧密相关。基于加速器装置的重离子核反应实验,是地面实验室模拟产生极端条件核物质的唯一手段,因而也成为研究核物质状态方程的有效途径。当核物质中的中子数远大于质子数时,例如中子星内部的情形,核物质状态方程中的主要贡献项是对称能项。迄今为止,对称能关于密度的函数是核物理和天体物理中一个未知而又非常重要的物理量。通过重离子核反应的实验和理论研究来确定对称能的密度依赖关系及其在核反应以及致密星天体事件中的物理效应,是当代核物理基础研究的重要前沿。文章介绍了中能重离子核反应和核物质状态方程的一些背景知识和研究方法,以及近年来的一些进展。     

Preface: High energy astrophysics

High energy astrophysics is one of the most active branches in the contemporary astrophysics. It studies astrophysical objects that emit X-ray and γ-ray photons, such as accreting super-massive and stellar-size black holes, and various species of neutron stars. With the operations of many space-borne and ground-based observational facilities, high energy astrophysics has enjoyed rapid development in the past decades. It is foreseen that the field will continue to advance rapidly in the coming decade, with possible ground-breaking discoveries of astrophysical sources in the high-energy neutrino and gravitational wave channels. This Special Issue of Frontiers of Physics is dedicated to a systematic survey of the field of high energy astrophysics as it stands in 2013.     

Precision mass measurements of short-lived nuclides at HIRFL-CSR in Lanzhou

In recent years, extensive short-lived nuclear mass measurements have been carried out at the Heavy- Ion Research Facility (HIRFL) in Lanzhou using Isochronous Mass Spectrometry (IMS). The obtained mass values have been successfully applied to nuclear structure and astrophysics studies. In this contribution, we give a brief introduction to the nuclear mass measurements at HIRFL-CSR facility. Main technical developments are described and recent results are summarized. Furthermore, we envision the future perspective for the next-generation storage ring facility HIAF in Huizhou.     

Quantum Monte Carlo calculations of symmetric nuclear matter

We present an accurate numerical study of the equation of state of nuclear matter based on realistic nucleon-nucleon interactions by means of auxiliary field diffusion Monte Carlo (AFDMC) calculations. The AFDMC method samples the spin and isospin degrees of freedom allowing for quantum simulations of large nucleonic systems and represents an important step forward towards a quantitative understanding of problems in nuclear structure and astrophysics.     

特洛伊木马方法及其应用最新进展

特洛伊木马方法是实验核天体物理中一种重要的间接测量方法,特别适合极低能区带电粒子裸核反应截面测量。在介绍特洛伊木马方法基本原理的基础上,重点讨论该方法近期在核天体物理应用中的一些重要实验结果,以及对未来研究的展望。主要介绍:AGB星s-过程关键中子源反应$ ^{{\rm{13}}}{\rm{C(\alpha ,n}}{{\rm{)}}^{{\rm{16}}}}{\rm{O}}$的间接测量,AGB星氟丰度超常现象相关核反应间接测量,以及最近热点–中等以上质量恒星碳燃烧核反应间接测量结果及相关争议。     

A new procedure for obtaining the Voigt function dependent upon the complex error function

This work proposes a new method for obtaining the differential equation of the Voigt function and, from this equation, expressing the Voigt function as dependent upon the complex error function. In addition, the integral expression of the successive derivatives of the Voigt function is given, and from this a method is generalized which permits the representation, also, of other functions depending on the complex error function. This enables us to simplify other functions which are the convolution of a Gaussian function with rational polynomial functions. Moreover, the relationship between the Lorentzian (w_L), Gaussian (w_G) and Voigt (w_V) widths at half maximum for the function is given, which is of great interest in diverse branches of physics, such as plasma spectroscopy, astrophysics, nuclear magnetic resonance, etc.