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Abstract Nuclear physics has been aiming at understanding of the origin, structure, and property of strongly interacting matters, which constitute nearly all visible matter in the universe. Despite tremendous breakthroughs and achievements over the past century, there still exists overarching questions that animate nuclear physics today and incite constructing next-generation heavy-ion accelerator complexes worldwide. In order to promote the national development of heavy-ion science and technology, China government approved the high-intensity heavy-ion accelerator facility (HIAF) in 2015, proposed by the Institute of Modern Physics, Chinese Academy of Sciences. HIAF is composed of a superconducting ion linear accelerator, a high-energy synchrotron booster, a high-energy radioactive isotope beam line, an experimental storage ring, and a few experimental setups. By using HIAF characterized with unprecedented intense ion beams from hydrogen through uranium, we can produce a large variety of exotic nuclear matters not normally found on the Earth, including super-heavy nuclides, short-lived extremely neutron-rich and proton-rich nuclides, finite nuclear matters in the quantum chromodynamics phase diagram, exotic nuclides containing hyperons, meson-nucleus-bound systems, and highly charged ions. Therefore, HIAF will bring researchers to the forefront of promoting the most vigorous and fascinating fields in nuclear physics, such as to explore the limits to the existence of nuclides in terms of proton and neutron numbers, to discover exotic nuclear structure and properties and then to study the physics behind, to understand the origin of heavy elements in the cosmos, to depict the phase diagram of strongly interacting matter, etc. In addition, HIAF will provide an excellent platform to develop heavy-ion applications in life science, space science, and material science. The construction of HIAF started up in December of 2018 and takes 7 years. The civil engineering and infrastructure are being constructed on time schedule and will be completed in July, 2023. R&D on key accelerator techniques are going on successfully, and prototypes of core devices are fabricated in collaboration with home and abroad universities, institutes, and companies. Presently, we come to the stage of invitation for bids and volume production of various apparatuses. We plan to start facility installation in summer of 2023. As a scientific user facility opening to domestic and oversea researchers, HIAF user community plays key roles in defining research programs and raising requirements. We call upon expertise, aspirations, and resources of a host of collaborators. Collaborations, dedicated to specific research subjects, are established and will be established. These collaborations develop new experimental techniques and methods and take responsibility for design and building of measurement systems. We have completed the design of experimental setups. A new gas-filled recoil separator and a novel storage-ring-based isochronous mass spectrometer are already built, and other measurement systems are under construction. The facility commissioning is scheduled at the end in the year of 2025. After into operation of the 2.5 billion Chinese yuan HIAF, this world-class facility will ensure the nation’s continued competitiveness in heavy-ion physics and technology through provision of outstanding discovery potential. Based on HIAF, we aim at establishing a world’s leading laboratory for research and education in nuclear science, accelerator physics and technology, and applications of energetic heavy ions to meet societal needs. In this paper, progress and status of civil engineering and infrastructure construction of HIAF are introduced, R&D on critical accelerator techniques and prototypes of core devices as well as development of new experimental techniques and methods are presented, and design and construction of experimental setups and the associated physics research programs are briefly depicted.

Nuclear physics has been aiming at understanding of the origin, structure, and property of strongly interacting matters, which constitute nearly all visible matter in the universe. Despite tremendous breakthroughs and achievements over the past century, there still exists overarching questions that animate nuclear physics today and incite constructing next-generation heavy-ion accelerator complexes worldwide. In order to promote the national development of heavy-ion science and technology, China government approved the high-intensity heavy-ion accelerator facility (HIAF) in 2015, proposed by the Institute of Modern Physics, Chinese Academy of Sciences. HIAF is composed of a superconducting ion linear accelerator, a high-energy synchrotron booster, a high-energy radioactive isotope beam line, an experimental storage ring, and a few experimental setups. By using HIAF characterized with unprecedented intense ion beams from hydrogen through uranium, we can produce a large variety of exotic nuclear matters not normally found on the Earth, including super-heavy nuclides, short-lived extremely neutron-rich and proton-rich nuclides, finite nuclear matters in the quantum chromodynamics phase diagram, exotic nuclides containing hyperons, meson-nucleus-bound systems, and highly charged ions. Therefore, HIAF will bring researchers to the forefront of promoting the most vigorous and fascinating fields in nuclear physics, such as to explore the limits to the existence of nuclides in terms of proton and neutron numbers, to discover exotic nuclear structure and properties and then to study the physics behind, to understand the origin of heavy elements in the cosmos, to depict the phase diagram of strongly interacting matter, etc. In addition, HIAF will provide an excellent platform to develop heavy-ion applications in life science, space science, and material science. The construction of HIAF started up in December of 2018 and takes 7 years. The civil engineering and infrastructure are being constructed on time schedule and will be completed in July, 2023. R&D on key accelerator techniques are going on successfully, and prototypes of core devices are fabricated in collaboration with home and abroad universities, institutes, and companies. Presently, we come to the stage of invitation for bids and volume production of various apparatuses. We plan to start facility installation in summer of 2023. As a scientific user facility opening to domestic and oversea researchers, HIAF user community plays key roles in defining research programs and raising requirements. We call upon expertise, aspirations, and resources of a host of collaborators. Collaborations, dedicated to specific research subjects, are established and will be established. These collaborations develop new experimental techniques and methods and take responsibility for design and building of measurement systems. We have completed the design of experimental setups. A new gas-filled recoil separator and a novel storage-ring-based isochronous mass spectrometer are already built, and other measurement systems are under construction. The facility commissioning is scheduled at the end in the year of 2025. After into operation of the 2.5 billion Chinese yuan HIAF, this world-class facility will ensure the nation's continued competitiveness in heavy-ion physics and technology through provision of outstanding discovery potential. Based on HIAF, we aim at establishing a world's leading laboratory for research and education in nuclear science, accelerator physics and technology, and applications of energetic heavy ions to meet societal needs. In this paper, progress and status of civil engineering and infrastructure construction of HIAF are introduced, R&D on critical accelerator techniques and prototypes of core devices as well as development of new experimental techniques and methods are presented, and design and construction of experimental setups and the associated physics research programs are briefly depicted. [ABSTRACT FROM AUTHOR]

A complex, long-range experimental program for the production of neutron-rich nuclei via multi-nucleon transfer (MNT) reactions and spontaneous fission (SF) inside the Cryogenic Stopping Cell (CSC) of the FRS Ion Catcher facility at GSI has been suggested and is under development. A key component is a new experimental set-up, consisting of a modified DC cage, a target-wheel, a beam-dump and a space charge suppression system. This setup replaces the standard electrode structure of the CSC, enabling generation of radioactive isotope beams by in-cell MNT reactions inside the CSC and the efficient and fast extraction of ions produced by MNT reactions or spontaneous fission. Furthermore, the system allows to do experiments with beams from the FRS with much higher rates and shorter half-lives. We present the specifications, design and production of this device. We also present the technical solution adopted against the space charge effect and the simulations that validate it. [ABSTRACT FROM AUTHOR]

The change of the shell structure in atomic nuclei, so-called “nuclear shell evolution”, occurs due to changes of major configurations through particle-hole excitations inside one nucleus, as well as due to variation of the number of constituent protons or neutrons. We have investigated how the shell evolution affects Gamow-Teller (GT) transitions that dominate the β decay in the region below 132Sn using the newly obtained experimental data on a long-lived isomer in 127Ag. The T1/2=67.5(9) ms isomer has been identified with a spin and parity of (27/2+) at an excitation energy of 1942−20+14 keV, and found to decay via an internal transition of an E3 character, which competes with the dominant β-decay branches towards the high-spin states in 127Cd. The underlying mechanism of a strong GT transition from the 127Ag isomer is discussed in terms of configuration-dependent optimization of the effective single-particle energies in the framework of a shell-model approach.

Abstract: The Prototype AT-TPC, a detector based on time projection chamber (TPC) technology was built at the National Superconducting Cyclotron Laboratory, Michigan State University. The chamber gas, called the active target, of the Prototype AT-TPC is utilized simultaneously as a reaction target and a tracking medium of charged particles for measuring low-energy nuclear reactions. In pursuit of luminosity, efficiency and resolution for reaction studies at a new generation of radioactive isotope facilities, the Prototype AT-TPC provides one of the largest active volumes in the world measuring 25cm in diameter and 50cm long along the beam axis, millimeter-precision tracking capability, and a high electric field of 1kV/cm/atm for fast electron drift, which limits the detector dead time. Commissioning of the detector using standard alpha sources and radioactive 6He beams has demonstrated the detector''s long-term stability as well as its performance, which allowed good reconstruction of reaction kinematics. [Copyright &y& Elsevier]

Abstract: A Micromegas detector was tested in a helium–carbon dioxide mixture at atmospheric pressure. A stable operation of the detector was confirmed at a gain of over 103 for a standard alpha source of 241Am. In order to realize a position-dependent gain, an anode strip was biased while keeping the other strips at the ground potential. The gain of the biased strip was reduced by one order of magnitude without affecting the gains of the neighboring strips. The energy spectra at 3.7MeV, the energy deposited by Am alpha particles in the sensitive region of the Micromegas, were obtained from the total charge and the charge deposit profile along the track. The energy resolutions for helium:carbon dioxide 90:10 mixture at a gas gain of about 100 were 11% FWHM for the former and 4% FWHM for the latter. The present results highlight the Micromegas as a promising electron amplifier of the forthcoming active target time projection chambers that will be dedicated to nuclear reactions with radioactive isotope beams. [Copyright &y& Elsevier]

Abstract: The SOLEROO (solenoidal exotic rare isotope) separator is under development for the production of light radioactive ion beams at the Australian National University. The separator is based on a single superconducting solenoid followed by two tracking detectors. Cross-section and beam purity measurements have been made to optimise the production of 6He, 8Li, 10Be and 12B beams. Having validated the trajectory simulation code SoliX, the optimal geometry for utilisation of the tracking detectors has also been explored. [Copyright &y& Elsevier]

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 (S 4 AT), 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. S 4 AT 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 contributed by coincident unreacted beam particles can be eliminated. Such a procedure, made possible by the multi-layer structure, is essential to eliminate the contribution from coincident unreacted beam particles, thus enabling its operation at a moderate beam intensity of up to a few Mcps. We evaluated the performance of S 4 AT by measuring the elastic proton–proton scattering using a 70-MeV proton beam at Cyclotron and Radioisotope Center (CYRIC), Tohoku University. [ABSTRACT FROM AUTHOR]