arXiv subjects

Hongna Liu

Publications and source records attributed to Hongna Liu.

4 recordsLinked to original sources

arXiv2026

The STRASSE liquid hydrogen target system

A compact liquid hydrogen target system has been developed for the Silicon Tracker for RAdioactive nuclei Studies at SAMURAI Experiments (STRASSE) at the RIKEN Nishina Center. This target, designed for proton-induced quasi-free scattering measurements in inverse kinematics, features a customizable cylindrical cell with a volume up to 125~mL which increases the reaction rate/luminosity, and thin Mylar walls to minimize the protons' angular straggling. The cryogenic system, operated at 20~K, is optimized for rapid cool-down ($\leq$ 5~h) and empty-target measurements, avoiding long experimental dead time. This new setup will allow for high-precision studies of nuclear structure using both missing-mass and in-flight prompt $\gamma$-ray spectroscopy techniques at the RIBF facility.

physics.ins-det↗

arXiv2026

Hyperon-Nucleon Spectrometer

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $\Lambda$ polarization puzzle, in which $\Lambda$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton ($pp$), proton-nucleus ($pA$), and nucleus-nucleus ($AA$) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of $pA$ and $AA$ collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

physics.ins-det↗

arXiv2024

Shell Migration at N = 32, 34 around Ca Region

The neutron numbers N = 32 and 34 are new magic numbers suggested in neutron-rich $pf$-shell nuclei. In this article, we discuss the experimental observables and state-of-the-art theoretical calculations that characterize and explain the shell evolution leading to new magic numbers. Particular focus shall be afforded to the experimental progress of the shell migration study at and beyond N = 32, 34 in Ar, K, Ca, and Sc isotopes at the RIBF using direct reactions with liquid hydrogen targets over the past ten years. The results prove the double magicity of \ts{52,54}Ca, and support the persistence of the N = 34 subshell closure below Z = 20 with a sharp weakening beyond Z = 20. Future measurements of intruder bands of N = 32, 34 nuclei and shell evolution towards N = 40 are discussed within the context of an upgraded RIBF facility and the development of novel detection systems.

nucl-ex↗

arXiv2024

Detectors for next-generation quasi-free scattering experiments at the RIBF

The advent of high-intensity radioactive ion beams has opened new avenues for nuclear structure research. By studying exotic ions, phenomena such as shell evolution, halos, and the limits of stability have been studied. In particular, Quasi-Free Scattering (QFS) experiments on hydrogen targets have proven to be a valuable tool to investigate the structure of exotic ions. Recently, a series of QFS experiments were performed at the Radioactive Isotope Beam Factory (RIBF) of the RIKEN Nishina Center employing the MINOS liquid hydrogen system. A fundamental part of the success of these experiments was the use of dedicated devices to measure the gamma-rays, charged particles, and neutrons emitted in the reactions. The experience gained during the past campaigns, as well as the upcoming upgrade of the RIBF facility call for improvements on the existing devices, as well as for the development of new detection systems. Here we review the main detection devices used at the RIBF for QFS experiments, and give an overview of the ongoing and upcoming developments.

physics.ins-det↗