Speaker
Description
Title: Study on Cluster Structures of 20Ne via Photonuclear Reactions
Authors: Leiming Hua1, Fei Lu2
Affiliations:
1. Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Fudan University, 200433, Shanghai, China
2. Shanghai Advanced Research Institute, Chinese Academy of Sciences, 201210, Shanghai, China
Abstract :
²⁰Ne, a typical α-conjugate nucleus, has served as a benchmark system for theoretical and experimental studies of α-cluster structures at high excitation energies. However, direct experimental evidence for its cluster configurations and decay properties remains limited. This is mainly due to the high level density, large decay widths, and complex decay mechanisms in this energy region. A detailed investigation of ²⁰Ne is important not only for understanding α clustering in light nuclei and exploring possible bosonic condensate states in nuclear matter, but also for providing crucial experimental constraints on the nuclear equation of state (EoS) and on nucleosynthesis processes in astrophysical environments.
To address these issues, we employ quasi‑monoenergetic γ‑ray beams from the Shanghai Laser Electron Gamma Source (SLEGS) at the Shanghai Synchrotron Radiation Facility (SSRF) to selectively excite ²⁰Ne to a state at Eₓ ≈ 21.8 MeV. This level has been proposed in both theoretical and experimental studies as a candidate for a 5α Bose‑condensed state in ²⁰Ne. The reaction products are measured in complete kinematics using the high-resolution active-target time projection chamber (fMeta-TPC) developed at Fudan University. The detector operates with a Ne+CH₄ (9:1 by volume) gas mixture, which simultaneously serves as the reaction target and the detection medium. The fMeta-TPC features near 4π solid-angle coverage, a low energy threshold, and high-precision three-dimensional track reconstruction. These capabilities enable the complete recording of the tracks, energy losses, and ranges of all α particles emitted in the reactions. In this measurement, a large sample of two-α decay events from ²⁰Ne has been observed. By reconstructing the track energies and angular distributions, we obtain key information on the excited-state properties, decay mechanisms, and branching ratios of ²⁰Ne.
Keywords: ²⁰Ne, cluster structure, photonuclear reaction, active-target TPC, SLEGS, 5α condensation